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Merge pull request #4332 from YosysHQ/krys/help_docs

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Add docs generation from cells help output
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KrystalDelusion 2024-10-17 05:01:35 +13:00 • committed by GitHub
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5
.github/workflows/prepare-docs.yml vendored
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@ -64,6 +64,11 @@ jobs:
docs/source/_images
docs/source/code_examples
- name: Install doc prereqs
shell: bash
run: |
make docs/reqs
- name: Test build docs
shell: bash
run: |

18
Makefile
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@ -981,8 +981,20 @@ endif
# also others, but so long as it doesn't fail this is enough to know we tried
docs/source/cmd/abc.rst: $(TARGETS) $(EXTRA_TARGETS)
mkdir -p docs/source/cmd
./$(PROGRAM_PREFIX)yosys -p 'help -write-rst-command-reference-manual'
$(Q) mkdir -p docs/source/cmd
$(Q) mkdir -p temp/docs/source/cmd
$(Q) cd temp && ./../$(PROGRAM_PREFIX)yosys -p 'help -write-rst-command-reference-manual'
$(Q) rsync -rc temp/docs/source/cmd docs/source
$(Q) rm -rf temp
docs/source/cell/word_add.rst: $(TARGETS) $(EXTRA_TARGETS)
$(Q) mkdir -p docs/source/cell
$(Q) mkdir -p temp/docs/source/cell
$(Q) cd temp && ./../$(PROGRAM_PREFIX)yosys -p 'help -write-rst-cells-manual'
$(Q) rsync -rc temp/docs/source/cell docs/source
$(Q) rm -rf temp
docs/source/generated/cells.json: docs/source/generated $(TARGETS) $(EXTRA_TARGETS)
$(Q) ./$(PROGRAM_PREFIX)yosys -p 'help -dump-cells-json $@'
PHONY: docs/gen_examples docs/gen_images docs/guidelines docs/usage docs/reqs
docs/gen_examples: $(TARGETS)
@ -1025,7 +1037,7 @@ docs/reqs:
$(Q) $(MAKE) -C docs reqs
.PHONY: docs/prep
docs/prep: docs/source/cmd/abc.rst docs/gen_examples docs/gen_images docs/guidelines docs/usage
docs/prep: docs/source/cmd/abc.rst docs/source/generated/cells.json docs/gen_examples docs/gen_images docs/guidelines docs/usage
DOC_TARGET ?= html
docs: docs/prep

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40
docs/source/_static/yosyshq.css
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@ -1,40 +0,0 @@
/* Don't hide the right sidebar as we're placing our fixed links there */
aside.no-toc {
display: block !important;
}
/* Colorful headings */
h1 {
color: var(--color-brand-primary);
}
h2, h3, h4, h5, h6 {
color: var(--color-brand-content);
}
/* Use a different color for external links */
a.external {
color: var(--color-brand-primary) !important;
}
.wy-table-responsive table td {
white-space: normal;
}
th {
text-align: left;
}
body[data-theme="dark"] {
.invert-helper {
filter: url("data:image/svg+xml,<svg xmlns='http%3A//www.w3.org/2000/svg'><filter id='f'><feColorMatrix color-interpolation-filters='sRGB' type='matrix' values='1.47 -1.73 -0.467 0 0.867 -0.733 0.467 -0.467 0 0.867 -0.667 -1.07 1.07 0 0.867 0 0 0 1.0 0'></feColorMatrix></filter></svg>#f");
}
}
@media (prefers-color-scheme: dark) {
body:not([data-theme="light"]) {
.invert-helper {
filter: url("data:image/svg+xml,<svg xmlns='http%3A//www.w3.org/2000/svg'><filter id='f'><feColorMatrix color-interpolation-filters='sRGB' type='matrix' values='1.47 -1.73 -0.467 0 0.867 -0.733 0.467 -0.467 0 0.867 -0.667 -1.07 1.07 0 0.867 0 0 0 1.0 0'></feColorMatrix></filter></svg>#f");
}
}
}

44
docs/source/_templates/page.html
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@ -1,44 +0,0 @@
{#
See https://github.com/pradyunsg/furo/blob/main/src/furo/theme/furo/page.html for the original
block this is overwriting.
The part that is customized is between the "begin of custom part" and "end of custom part"
comments below. It uses the same styles as the existing right sidebar code.
#}
{% extends "furo/page.html" %}
{% block right_sidebar %}
<div class="toc-sticky toc-scroll">
{# begin of custom part #}
<div class="toc-title-container">
<span class="toc-title">
YosysHQ
</span>
</div>
<div class="toc-tree-container yosyshq-links" style="padding-bottom: 0">
<div class="toc-tree">
<ul>
<li></li>
<li><a class="reference external" href="https://yosyshq.readthedocs.io">Docs</a></li>
<li><a class="reference external" href="https://blog.yosyshq.com">Blog</a></li>
<li><a class="reference external" href="https://www.yosyshq.com">Website</a></li>
</ul>
</div>
</div>
{# end of custom part #}
{% if not furo_hide_toc %}
<div class="toc-title-container">
<span class="toc-title">
{{ _("On this page") }}
</span>
</div>
<div class="toc-tree-container">
<div class="toc-tree">
{{ toc }}
</div>
</div>
{% endif %}
</div>
{% endblock %}

18
docs/source/appendix.rst
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@ -1,18 +0,0 @@
Appendix
========
.. toctree::
:maxdepth: 2
:includehidden:
appendix/primer
appendix/auxlibs
appendix/auxprogs
bib
.. toctree::
:maxdepth: 1
:includehidden:
cmd_ref

14
docs/source/appendix/auxlibs.rst
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@ -29,7 +29,7 @@ ezSAT
The files in ``libs/ezsat`` provide a library for simplifying generating CNF
formulas for SAT solvers. It also contains bindings of MiniSAT. The ezSAT
library is written by C. Wolf. It is used by the :cmd:ref:`sat` pass (see
library is written by C. Wolf. It is used by the `sat` pass (see
:doc:`/cmd/sat`).
fst
@ -37,22 +37,22 @@ fst
``libfst`` files from `gtkwave`_ are included in ``libs/fst`` to support
reading/writing signal traces from/to the GTKWave developed FST format. This is
primarily used in the :cmd:ref:`sim` command.
primarily used in the `sim` command.
.. _gtkwave: https://github.com/gtkwave/gtkwave
json11
------
For reading/writing designs from/to JSON, :cmd:ref:`read_json` and
:cmd:ref:`write_json` should be used. For everything else there is the `json11
For reading/writing designs from/to JSON, `read_json` and
`write_json` should be used. For everything else there is the `json11
library`_:
json11 is a tiny JSON library for C++11, providing JSON parsing and
serialization.
This library is used for outputting machine-readable statistics (:cmd:ref:`stat`
with ``-json`` flag), using the RPC frontend (:cmd:ref:`connect_rpc`), and the
This library is used for outputting machine-readable statistics (`stat`
with ``-json`` flag), using the RPC frontend (`connect_rpc`), and the
yosys-witness ``yw`` format.
.. _json11 library: https://github.com/dropbox/json11
@ -61,7 +61,7 @@ MiniSAT
-------
The files in ``libs/minisat`` provide a high-performance SAT solver, used by the
:cmd:ref:`sat` command.
`sat` command.
SHA1
----

2
docs/source/appendix/env_vars.rst
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@ -3,7 +3,7 @@ Yosys environment variables
``HOME``
Yosys command history is stored in :file:`$HOME/.yosys_history`. Graphics
(from :cmd:ref:`show` and :cmd:ref:`viz` commands) will output to this
(from `show` and `viz` commands) will output to this
directory by default. This environment variable is also used in some cases
for resolving filenames with :file:`~`.

4
docs/source/yosys_internals/formats/rtlil_text.rst → docs/source/appendix/rtlil_text.rst
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@ -223,8 +223,8 @@ Cells
Declares a cell, with zero or more attributes, with the given identifier and
type in the enclosing module.
Cells perform functions on input signals. See
:doc:`/yosys_internals/formats/cell_library` for a detailed list of cell types.
Cells perform functions on input signals. See :doc:`/cell_index` for a detailed
list of cell types.
.. code:: BNF

53
docs/source/cell/gate_comb_combined.rst Normal file
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@ -0,0 +1,53 @@
.. role:: verilog(code)
:language: Verilog
Combinatorial cells (combined)
------------------------------
These cells combine two or more combinatorial cells (simple) into a single cell.
.. table:: Cell types for gate level combinatorial cells (combined)
======================================= =============
Verilog Cell Type
======================================= =============
:verilog:`Y = A & ~B` `$_ANDNOT_`
:verilog:`Y = A | ~B` `$_ORNOT_`
:verilog:`Y = ~((A & B) | C)` `$_AOI3_`
:verilog:`Y = ~((A | B) & C)` `$_OAI3_`
:verilog:`Y = ~((A & B) | (C & D))` `$_AOI4_`
:verilog:`Y = ~((A | B) & (C | D))` `$_OAI4_`
:verilog:`Y = ~(S ? B : A)` `$_NMUX_`
(see below) `$_MUX4_`
(see below) `$_MUX8_`
(see below) `$_MUX16_`
======================================= =============
The `$_MUX4_`, `$_MUX8_` and `$_MUX16_` cells are used to model wide muxes, and
correspond to the following Verilog code:
.. code-block:: verilog
:force:
// $_MUX4_
assign Y = T ? (S ? D : C) :
(S ? B : A);
// $_MUX8_
assign Y = U ? T ? (S ? H : G) :
(S ? F : E) :
T ? (S ? D : C) :
(S ? B : A);
// $_MUX16_
assign Y = V ? U ? T ? (S ? P : O) :
(S ? N : M) :
T ? (S ? L : K) :
(S ? J : I) :
U ? T ? (S ? H : G) :
(S ? F : E) :
T ? (S ? D : C) :
(S ? B : A);
.. autocellgroup:: comb_combined
:members:
:source:
:linenos:

26
docs/source/cell/gate_comb_simple.rst Normal file
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@ -0,0 +1,26 @@
.. role:: verilog(code)
:language: Verilog
Combinatorial cells (simple)
----------------------------
.. table:: Cell types for gate level combinatorial cells (simple)
======================================= =============
Verilog Cell Type
======================================= =============
:verilog:`Y = A` `$_BUF_`
:verilog:`Y = ~A` `$_NOT_`
:verilog:`Y = A & B` `$_AND_`
:verilog:`Y = ~(A & B)` `$_NAND_`
:verilog:`Y = A | B` `$_OR_`
:verilog:`Y = ~(A | B)` `$_NOR_`
:verilog:`Y = A ^ B` `$_XOR_`
:verilog:`Y = ~(A ^ B)` `$_XNOR_`
:verilog:`Y = S ? B : A` `$_MUX_`
======================================= =============
.. autocellgroup:: comb_simple
:members:
:source:
:linenos:

8
docs/source/cell/gate_other.rst Normal file
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@ -0,0 +1,8 @@
Other gate-level cells
----------------------
.. autocellgroup:: gate_other
:caption: Other gate-level cells
:members:
:source:
:linenos:

231
docs/source/cell/gate_reg_ff.rst Normal file
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@ -0,0 +1,231 @@
.. role:: verilog(code)
:language: Verilog
Flip-flop cells
---------------
The cell types `$_DFF_N_` and `$_DFF_P_` represent d-type flip-flops.
.. table:: Cell types for basic flip-flops
======================================= =============
Verilog Cell Type
======================================= =============
:verilog:`always @(negedge C) Q <= D` `$_DFF_N_`
:verilog:`always @(posedge C) Q <= D` `$_DFF_P_`
======================================= =============
The cell types ``$_DFFE_[NP][NP]_`` implement d-type flip-flops with enable. The
values in the table for these cell types relate to the following Verilog code
template.
.. code-block:: verilog
:force:
always @(CLK_EDGE C)
if (EN == EN_LVL)
Q <= D;
.. table:: Cell types for gate level logic networks (FFs with enable)
:name: tab:CellLib_gates_dffe
================== ============= ============
:math:`ClkEdge` :math:`EnLvl` Cell Type
================== ============= ============
:verilog:`negedge` ``0`` `$_DFFE_NN_`
:verilog:`negedge` ``1`` `$_DFFE_NP_`
:verilog:`posedge` ``0`` `$_DFFE_PN_`
:verilog:`posedge` ``1`` `$_DFFE_PP_`
================== ============= ============
The cell types ``$_DFF_[NP][NP][01]_`` implement d-type flip-flops with
asynchronous reset. The values in the table for these cell types relate to the
following Verilog code template, where ``RST_EDGE`` is ``posedge`` if
``RST_LVL`` if ``1``, and ``negedge`` otherwise.
.. code-block:: verilog
:force:
always @(CLK_EDGE C, RST_EDGE R)
if (R == RST_LVL)
Q <= RST_VAL;
else
Q <= D;
The cell types ``$_SDFF_[NP][NP][01]_`` implement d-type flip-flops with
synchronous reset. The values in the table for these cell types relate to the
following Verilog code template:
.. code-block:: verilog
:force:
always @(CLK_EDGE C)
if (R == RST_LVL)
Q <= RST_VAL;
else
Q <= D;
.. table:: Cell types for gate level logic networks (FFs with reset)
:name: tab:CellLib_gates_adff
================== ============== ============== ===========================
:math:`ClkEdge` :math:`RstLvl` :math:`RstVal` Cell Type
================== ============== ============== ===========================
:verilog:`negedge` ``0`` ``0`` `$_DFF_NN0_`, `$_SDFF_NN0_`
:verilog:`negedge` ``0`` ``1`` `$_DFF_NN1_`, `$_SDFF_NN1_`
:verilog:`negedge` ``1`` ``0`` `$_DFF_NP0_`, `$_SDFF_NP0_`
:verilog:`negedge` ``1`` ``1`` `$_DFF_NP1_`, `$_SDFF_NP1_`
:verilog:`posedge` ``0`` ``0`` `$_DFF_PN0_`, `$_SDFF_PN0_`
:verilog:`posedge` ``0`` ``1`` `$_DFF_PN1_`, `$_SDFF_PN1_`
:verilog:`posedge` ``1`` ``0`` `$_DFF_PP0_`, `$_SDFF_PP0_`
:verilog:`posedge` ``1`` ``1`` `$_DFF_PP1_`, `$_SDFF_PP1_`
================== ============== ============== ===========================
The cell types ``$_DFFE_[NP][NP][01][NP]_`` implement d-type flip-flops with
asynchronous reset and enable. The values in the table for these cell types
relate to the following Verilog code template, where ``RST_EDGE`` is ``posedge``
if ``RST_LVL`` if ``1``, and ``negedge`` otherwise.
.. code-block:: verilog
:force:
always @(CLK_EDGE C, RST_EDGE R)
if (R == RST_LVL)
Q <= RST_VAL;
else if (EN == EN_LVL)
Q <= D;
The cell types ``$_SDFFE_[NP][NP][01][NP]_`` implement d-type flip-flops with
synchronous reset and enable, with reset having priority over enable. The values
in the table for these cell types relate to the following Verilog code template:
.. code-block:: verilog
:force:
always @(CLK_EDGE C)
if (R == RST_LVL)
Q <= RST_VAL;
else if (EN == EN_LVL)
Q <= D;
The cell types ``$_SDFFCE_[NP][NP][01][NP]_`` implement d-type flip-flops with
synchronous reset and enable, with enable having priority over reset. The values
in the table for these cell types relate to the following Verilog code template:
.. code-block:: verilog
:force:
always @(CLK_EDGE C)
if (EN == EN_LVL)
if (R == RST_LVL)
Q <= RST_VAL;
else
Q <= D;
.. table:: Cell types for gate level logic networks (FFs with reset and enable)
:name: tab:CellLib_gates_adffe
================== ============== ============== ============= =================================================
:math:`ClkEdge` :math:`RstLvl` :math:`RstVal` :math:`EnLvl` Cell Type
================== ============== ============== ============= =================================================
:verilog:`negedge` ``0`` ``0`` ``0`` `$_DFFE_NN0N_`, `$_SDFFE_NN0N_`, `$_SDFFCE_NN0N_`
:verilog:`negedge` ``0`` ``0`` ``1`` `$_DFFE_NN0P_`, `$_SDFFE_NN0P_`, `$_SDFFCE_NN0P_`
:verilog:`negedge` ``0`` ``1`` ``0`` `$_DFFE_NN1N_`, `$_SDFFE_NN1N_`, `$_SDFFCE_NN1N_`
:verilog:`negedge` ``0`` ``1`` ``1`` `$_DFFE_NN1P_`, `$_SDFFE_NN1P_`, `$_SDFFCE_NN1P_`
:verilog:`negedge` ``1`` ``0`` ``0`` `$_DFFE_NP0N_`, `$_SDFFE_NP0N_`, `$_SDFFCE_NP0N_`
:verilog:`negedge` ``1`` ``0`` ``1`` `$_DFFE_NP0P_`, `$_SDFFE_NP0P_`, `$_SDFFCE_NP0P_`
:verilog:`negedge` ``1`` ``1`` ``0`` `$_DFFE_NP1N_`, `$_SDFFE_NP1N_`, `$_SDFFCE_NP1N_`
:verilog:`negedge` ``1`` ``1`` ``1`` `$_DFFE_NP1P_`, `$_SDFFE_NP1P_`, `$_SDFFCE_NP1P_`
:verilog:`posedge` ``0`` ``0`` ``0`` `$_DFFE_PN0N_`, `$_SDFFE_PN0N_`, `$_SDFFCE_PN0N_`
:verilog:`posedge` ``0`` ``0`` ``1`` `$_DFFE_PN0P_`, `$_SDFFE_PN0P_`, `$_SDFFCE_PN0P_`
:verilog:`posedge` ``0`` ``1`` ``0`` `$_DFFE_PN1N_`, `$_SDFFE_PN1N_`, `$_SDFFCE_PN1N_`
:verilog:`posedge` ``0`` ``1`` ``1`` `$_DFFE_PN1P_`, `$_SDFFE_PN1P_`, `$_SDFFCE_PN1P_`
:verilog:`posedge` ``1`` ``0`` ``0`` `$_DFFE_PP0N_`, `$_SDFFE_PP0N_`, `$_SDFFCE_PP0N_`
:verilog:`posedge` ``1`` ``0`` ``1`` `$_DFFE_PP0P_`, `$_SDFFE_PP0P_`, `$_SDFFCE_PP0P_`
:verilog:`posedge` ``1`` ``1`` ``0`` `$_DFFE_PP1N_`, `$_SDFFE_PP1N_`, `$_SDFFCE_PP1N_`
:verilog:`posedge` ``1`` ``1`` ``1`` `$_DFFE_PP1P_`, `$_SDFFE_PP1P_`, `$_SDFFCE_PP1P_`
================== ============== ============== ============= =================================================
The cell types ``$_DFFSR_[NP][NP][NP]_`` implement d-type flip-flops with
asynchronous set and reset. The values in the table for these cell types relate
to the following Verilog code template, where ``RST_EDGE`` is ``posedge`` if
``RST_LVL`` if ``1``, ``negedge`` otherwise, and ``SET_EDGE`` is ``posedge`` if
``SET_LVL`` if ``1``, ``negedge`` otherwise.
.. code-block:: verilog
:force:
always @(CLK_EDGE C, RST_EDGE R, SET_EDGE S)
if (R == RST_LVL)
Q <= 0;
else if (S == SET_LVL)
Q <= 1;
else
Q <= D;
.. table:: Cell types for gate level logic networks (FFs with set and reset)
:name: tab:CellLib_gates_dffsr
================== ============== ============== ==============
:math:`ClkEdge` :math:`SetLvl` :math:`RstLvl` Cell Type
================== ============== ============== ==============
:verilog:`negedge` ``0`` ``0`` `$_DFFSR_NNN_`
:verilog:`negedge` ``0`` ``1`` `$_DFFSR_NNP_`
:verilog:`negedge` ``1`` ``0`` `$_DFFSR_NPN_`
:verilog:`negedge` ``1`` ``1`` `$_DFFSR_NPP_`
:verilog:`posedge` ``0`` ``0`` `$_DFFSR_PNN_`
:verilog:`posedge` ``0`` ``1`` `$_DFFSR_PNP_`
:verilog:`posedge` ``1`` ``0`` `$_DFFSR_PPN_`
:verilog:`posedge` ``1`` ``1`` `$_DFFSR_PPP_`
================== ============== ============== ==============
The cell types ``$_DFFSRE_[NP][NP][NP][NP]_`` implement d-type flip-flops with
asynchronous set and reset and enable. The values in the table for these cell
types relate to the following Verilog code template, where ``RST_EDGE`` is
``posedge`` if ``RST_LVL`` if ``1``, ``negedge`` otherwise, and ``SET_EDGE`` is
``posedge`` if ``SET_LVL`` if ``1``, ``negedge`` otherwise.
.. code-block:: verilog
:force:
always @(CLK_EDGE C, RST_EDGE R, SET_EDGE S)
if (R == RST_LVL)
Q <= 0;
else if (S == SET_LVL)
Q <= 1;
else if (E == EN_LVL)
Q <= D;
.. table:: Cell types for gate level logic networks (FFs with set and reset and enable)
:name: tab:CellLib_gates_dffsre
================== ============== ============== ============= ================
:math:`ClkEdge` :math:`SetLvl` :math:`RstLvl` :math:`EnLvl` Cell Type
================== ============== ============== ============= ================
:verilog:`negedge` ``0`` ``0`` ``0`` `$_DFFSRE_NNNN_`
:verilog:`negedge` ``0`` ``0`` ``1`` `$_DFFSRE_NNNP_`
:verilog:`negedge` ``0`` ``1`` ``0`` `$_DFFSRE_NNPN_`
:verilog:`negedge` ``0`` ``1`` ``1`` `$_DFFSRE_NNPP_`
:verilog:`negedge` ``1`` ``0`` ``0`` `$_DFFSRE_NPNN_`
:verilog:`negedge` ``1`` ``0`` ``1`` `$_DFFSRE_NPNP_`
:verilog:`negedge` ``1`` ``1`` ``0`` `$_DFFSRE_NPPN_`
:verilog:`negedge` ``1`` ``1`` ``1`` `$_DFFSRE_NPPP_`
:verilog:`posedge` ``0`` ``0`` ``0`` `$_DFFSRE_PNNN_`
:verilog:`posedge` ``0`` ``0`` ``1`` `$_DFFSRE_PNNP_`
:verilog:`posedge` ``0`` ``1`` ``0`` `$_DFFSRE_PNPN_`
:verilog:`posedge` ``0`` ``1`` ``1`` `$_DFFSRE_PNPP_`
:verilog:`posedge` ``1`` ``0`` ``0`` `$_DFFSRE_PPNN_`
:verilog:`posedge` ``1`` ``0`` ``1`` `$_DFFSRE_PPNP_`
:verilog:`posedge` ``1`` ``1`` ``0`` `$_DFFSRE_PPPN_`
:verilog:`posedge` ``1`` ``1`` ``1`` `$_DFFSRE_PPPP_`
================== ============== ============== ============= ================
.. todo:: flip-flops with async load, ``$_ALDFFE?_[NP]{2,3}_``
.. autocellgroup:: reg_ff
:members:
:source:
:linenos:

105
docs/source/cell/gate_reg_latch.rst Normal file
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@ -0,0 +1,105 @@
.. role:: verilog(code)
:language: Verilog
Latch cells
-----------
The cell types `$_DLATCH_N_` and `$_DLATCH_P_` represent d-type latches.
.. table:: Cell types for basic latches
======================================= =============
Verilog Cell Type
======================================= =============
:verilog:`always @* if (!E) Q <= D` `$_DLATCH_N_`
:verilog:`always @* if (E) Q <= D` `$_DLATCH_P_`
======================================= =============
The cell types ``$_DLATCH_[NP][NP][01]_`` implement d-type latches with reset.
The values in the table for these cell types relate to the following Verilog
code template:
.. code-block:: verilog
:force:
always @*
if (R == RST_LVL)
Q <= RST_VAL;
else if (E == EN_LVL)
Q <= D;
.. table:: Cell types for gate level logic networks (latches with reset)
:name: tab:CellLib_gates_adlatch
============= ============== ============== ===============
:math:`EnLvl` :math:`RstLvl` :math:`RstVal` Cell Type
============= ============== ============== ===============
``0`` ``0`` ``0`` `$_DLATCH_NN0_`
``0`` ``0`` ``1`` `$_DLATCH_NN1_`
``0`` ``1`` ``0`` `$_DLATCH_NP0_`
``0`` ``1`` ``1`` `$_DLATCH_NP1_`
``1`` ``0`` ``0`` `$_DLATCH_PN0_`
``1`` ``0`` ``1`` `$_DLATCH_PN1_`
``1`` ``1`` ``0`` `$_DLATCH_PP0_`
``1`` ``1`` ``1`` `$_DLATCH_PP1_`
============= ============== ============== ===============
The cell types ``$_DLATCHSR_[NP][NP][NP]_`` implement d-type latches with set
and reset. The values in the table for these cell types relate to the following
Verilog code template:
.. code-block:: verilog
:force:
always @*
if (R == RST_LVL)
Q <= 0;
else if (S == SET_LVL)
Q <= 1;
else if (E == EN_LVL)
Q <= D;
.. table:: Cell types for gate level logic networks (latches with set and reset)
:name: tab:CellLib_gates_dlatchsr
============= ============== ============== =================
:math:`EnLvl` :math:`SetLvl` :math:`RstLvl` Cell Type
============= ============== ============== =================
``0`` ``0`` ``0`` `$_DLATCHSR_NNN_`
``0`` ``0`` ``1`` `$_DLATCHSR_NNP_`
``0`` ``1`` ``0`` `$_DLATCHSR_NPN_`
``0`` ``1`` ``1`` `$_DLATCHSR_NPP_`
``1`` ``0`` ``0`` `$_DLATCHSR_PNN_`
``1`` ``0`` ``1`` `$_DLATCHSR_PNP_`
``1`` ``1`` ``0`` `$_DLATCHSR_PPN_`
``1`` ``1`` ``1`` `$_DLATCHSR_PPP_`
============= ============== ============== =================
The cell types ``$_SR_[NP][NP]_`` implement sr-type latches. The values in the
table for these cell types relate to the following Verilog code template:
.. code-block:: verilog
:force:
always @*
if (R == RST_LVL)
Q <= 0;
else if (S == SET_LVL)
Q <= 1;
.. table:: Cell types for gate level logic networks (SR latches)
:name: tab:CellLib_gates_sr
============== ============== ==========
:math:`SetLvl` :math:`RstLvl` Cell Type
============== ============== ==========
``0`` ``0`` `$_SR_NN_`
``0`` ``1`` `$_SR_NP_`
``1`` ``0`` `$_SR_PN_`
``1`` ``1`` `$_SR_PP_`
============== ============== ==========
.. autocellgroup:: reg_latch
:members:
:source:
:linenos:

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.. _sec:celllib_gates:
Gate-level cells
----------------
For gate level logic networks, fixed function single bit cells are used that do
not provide any parameters.
Simulation models for these cells can be found in the file
:file:`techlibs/common/simcells.v` in the Yosys source tree.
In most cases gate level logic networks are created from RTL networks using the
techmap pass. The flip-flop cells from the gate level logic network can be
mapped to physical flip-flop cells from a Liberty file using the dfflibmap pass.
The combinatorial logic cells can be mapped to physical cells from a Liberty
file via ABC using the abc pass.
.. toctree::
:maxdepth: 2
/cell/gate_comb_simple
/cell/gate_comb_combined
/cell/gate_reg_ff
/cell/gate_reg_latch
/cell/gate_other

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Word-level cells
----------------
Most of the RTL cells closely resemble the operators available in HDLs such as
Verilog or VHDL. Therefore Verilog operators are used in the following sections
to define the behaviour of the RTL cells.
Note that all RTL cells have parameters indicating the size of inputs and
outputs. When passes modify RTL cells they must always keep the values of these
parameters in sync with the size of the signals connected to the inputs and
outputs.
Simulation models for the RTL cells can be found in the file
:file:`techlibs/common/simlib.v` in the Yosys source tree.
.. toctree::
:maxdepth: 2
/cell/word_unary
/cell/word_binary
/cell/word_mux
/cell/word_reg
/cell/word_mem
/cell/word_fsm
/cell/word_arith
/cell/word_logic
/cell/word_spec
/cell/word_formal
/cell/word_debug
/cell/word_wire

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Cell properties
---------------
.. cell:defprop:: is_evaluable
These cells are able to be used in conjunction with the `eval` command. Some
passes, such as `opt_expr`, may also be able to perform additional
optimizations on cells which are evaluable.
.. cell:defprop:: x-aware
Some passes will treat these cells as the non 'x' aware cell. For example,
during synthesis `$eqx` will typically be treated as `$eq`.
.. cell:defprop:: x-output
These cells can produce 'x' output even if all inputs are defined. For
example, a `$div` cell with divisor (``B``) equal to zero has undefined
output.
Refer to the :ref:`propindex` for the list of cells with a given property.

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Coarse arithmetics
------------------
.. todo:: Add information about `$alu`, `$fa`, and `$lcu` cells.
The `$macc` cell type represents a generalized multiply and accumulate
operation. The cell is purely combinational. It outputs the result of summing up
a sequence of products and other injected summands.
.. code-block::
Y = 0 +- a0factor1 * a0factor2 +- a1factor1 * a1factor2 +- ...
+ B[0] + B[1] + ...
The A port consists of concatenated pairs of multiplier inputs ("factors"). A
zero length factor2 acts as a constant 1, turning factor1 into a simple summand.
In this pseudocode, ``u(foo)`` means an unsigned int that's foo bits long.
.. code-block::
struct A {
u(CONFIG.mul_info[0].factor1_len) a0factor1;
u(CONFIG.mul_info[0].factor2_len) a0factor2;
u(CONFIG.mul_info[1].factor1_len) a1factor1;
u(CONFIG.mul_info[1].factor2_len) a1factor2;
...
};
The cell's ``CONFIG`` parameter determines the layout of cell port ``A``. The
CONFIG parameter carries the following information:
.. code-block::
struct CONFIG {
u4 num_bits;
struct mul_info {
bool is_signed;
bool is_subtract;
u(num_bits) factor1_len;
u(num_bits) factor2_len;
}[num_ports];
};
B is an array of concatenated 1-bit-wide unsigned integers to also be summed up.
.. autocellgroup:: arith
:members:
:source:
:linenos:

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.. role:: verilog(code)
:language: Verilog
Binary operators
~~~~~~~~~~~~~~~~
All binary RTL cells have two input ports ``A`` and ``B`` and one output port
``Y``. They also have the following parameters:
``A_SIGNED``
Set to a non-zero value if the input ``A`` is signed and therefore should be
sign-extended when needed.
``A_WIDTH``
The width of the input port ``A``.
``B_SIGNED``
Set to a non-zero value if the input ``B`` is signed and therefore should be
sign-extended when needed.
``B_WIDTH``
The width of the input port ``B``.
``Y_WIDTH``
The width of the output port ``Y``.
.. table:: Cell types for binary operators with their corresponding Verilog expressions.
======================= =============== ======================= ===========
Verilog Cell Type Verilog Cell Type
======================= =============== ======================= ===========
:verilog:`Y = A & B` `$and` :verilog:`Y = A ** B` `$pow`
:verilog:`Y = A | B` `$or` :verilog:`Y = A < B` `$lt`
:verilog:`Y = A ^ B` `$xor` :verilog:`Y = A <= B` `$le`
:verilog:`Y = A ~^ B` `$xnor` :verilog:`Y = A == B` `$eq`
:verilog:`Y = A << B` `$shl` :verilog:`Y = A != B` `$ne`
:verilog:`Y = A >> B` `$shr` :verilog:`Y = A >= B` `$ge`
:verilog:`Y = A <<< B` `$sshl` :verilog:`Y = A > B` `$gt`
:verilog:`Y = A >>> B` `$sshr` :verilog:`Y = A + B` `$add`
:verilog:`Y = A && B` `$logic_and` :verilog:`Y = A - B` `$sub`
:verilog:`Y = A || B` `$logic_or` :verilog:`Y = A * B` `$mul`
:verilog:`Y = A === B` `$eqx` :verilog:`Y = A / B` `$div`
:verilog:`Y = A !== B` `$nex` :verilog:`Y = A % B` `$mod`
``N/A`` `$shift` ``N/A`` `$divfloor`
``N/A`` `$shiftx` ``N/A`` `$modfloor`
======================= =============== ======================= ===========
The `$shl` and `$shr` cells implement logical shifts, whereas the `$sshl` and
`$sshr` cells implement arithmetic shifts. The `$shl` and `$sshl` cells
implement the same operation. All four of these cells interpret the second
operand as unsigned, and require ``B_SIGNED`` to be zero.
Two additional shift operator cells are available that do not directly
correspond to any operator in Verilog, `$shift` and `$shiftx`. The `$shift` cell
performs a right logical shift if the second operand is positive (or unsigned),
and a left logical shift if it is negative. The `$shiftx` cell performs the same
operation as the `$shift` cell, but the vacated bit positions are filled with
undef (x) bits, and corresponds to the Verilog indexed part-select expression.
For the binary cells that output a logical value (`$logic_and`, `$logic_or`,
`$eqx`, `$nex`, `$lt`, `$le`, `$eq`, `$ne`, `$ge`, `$gt`), when the ``Y_WIDTH``
parameter is greater than 1, the output is zero-extended, and only the least
significant bit varies.
Division and modulo cells are available in two rounding modes. The original
`$div` and `$mod` cells are based on truncating division, and correspond to the
semantics of the verilog ``/`` and ``%`` operators. The `$divfloor` and
`$modfloor` cells represent flooring division and flooring modulo, the latter of
which corresponds to the ``%`` operator in Python. See the following table for a
side-by-side comparison between the different semantics.
.. table:: Comparison between different rounding modes for division and modulo cells.
+-----------+--------+-----------+-----------+-----------+-----------+
| Division | Result | Truncating | Flooring |
+-----------+--------+-----------+-----------+-----------+-----------+
| | | $div | $mod | $divfloor | $modfloor |
+===========+========+===========+===========+===========+===========+
| -10 / 3 | -3.3 | -3 | -1 | -4 | 2 |
+-----------+--------+-----------+-----------+-----------+-----------+
| 10 / -3 | -3.3 | -3 | 1 | -4 | -2 |
+-----------+--------+-----------+-----------+-----------+-----------+
| -10 / -3 | 3.3 | 3 | -1 | 3 | -1 |
+-----------+--------+-----------+-----------+-----------+-----------+
| 10 / 3 | 3.3 | 3 | 1 | 3 | 1 |
+-----------+--------+-----------+-----------+-----------+-----------+
.. autocellgroup:: binary
:members:
:source:
:linenos:

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.. role:: verilog(code)
:language: Verilog
Debugging cells
---------------
The `$print` cell is used to log the values of signals, akin to (and
translatable to) the ``$display`` and ``$write`` family of tasks in Verilog. It
has the following parameters:
``FORMAT``
The internal format string. The syntax is described below.
``ARGS_WIDTH``
The width (in bits) of the signal on the ``ARGS`` port.
``TRG_ENABLE``
True if triggered on specific signals defined in ``TRG``; false if triggered
whenever ``ARGS`` or ``EN`` change and ``EN`` is 1.
If ``TRG_ENABLE`` is true, the following parameters also apply:
``TRG_WIDTH``
The number of bits in the ``TRG`` port.
``TRG_POLARITY``
For each bit in ``TRG``, 1 if that signal is positive-edge triggered, 0 if
negative-edge triggered.
``PRIORITY``
When multiple `$print` or `$check` cells fire on the same trigger, they
execute in descending priority order.
Ports:
``TRG``
The signals that control when this `$print` cell is triggered.
If the width of this port is zero and ``TRG_ENABLE`` is true, the cell is
triggered during initial evaluation (time zero) only.
``EN``
Enable signal for the whole cell.
``ARGS``
The values to be displayed, in format string order.
.. autocellgroup:: debug
:members:
:source:
:linenos:
Format string syntax
~~~~~~~~~~~~~~~~~~~~
The format string syntax resembles Python f-strings. Regular text is passed
through unchanged until a format specifier is reached, starting with a ``{``.
Format specifiers have the following syntax. Unless noted, all items are
required:
``{``
Denotes the start of the format specifier.
size
Signal size in bits; this many bits are consumed from the ``ARGS`` port by
this specifier.
``:``
Separates the size from the remaining items.
justify
``>`` for right-justified, ``<`` for left-justified.
padding
``0`` for zero-padding, or a space for space-padding.
width\ *?*
(optional) The number of characters wide to pad to.
base
* ``b`` for base-2 integers (binary)
* ``o`` for base-8 integers (octal)
* ``d`` for base-10 integers (decimal)
* ``h`` for base-16 integers (hexadecimal)
* ``c`` for ASCII characters/strings
* ``t`` and ``r`` for simulation time (corresponding to :verilog:`$time` and
:verilog:`$realtime`)
For integers, this item may follow:
``+``\ *?*
(optional, decimals only) Include a leading plus for non-negative numbers.
This can assist with symmetry with negatives in tabulated output.
signedness
``u`` for unsigned, ``s`` for signed. This distinction is only respected
when rendering decimals.
ASCII characters/strings have no special options, but the signal size must be
divisible by 8.
For simulation time, the signal size must be zero.
Finally:
``}``
Denotes the end of the format specifier.
Some example format specifiers:
+ ``{8:>02hu}`` - 8-bit unsigned integer rendered as hexadecimal,
right-justified, zero-padded to 2 characters wide.
+ ``{32:< 15d+s}`` - 32-bit signed integer rendered as decimal, left-justified,
space-padded to 15 characters wide, positive values prefixed with ``+``.
+ ``{16:< 10hu}`` - 16-bit unsigned integer rendered as hexadecimal,
left-justified, space-padded to 10 characters wide.
+ ``{0:>010t}`` - simulation time, right-justified, zero-padded to 10 characters
wide.
To include literal ``{`` and ``}`` characters in your format string, use ``{{``
and ``}}`` respectively.
It is an error for a format string to consume more or less bits from ``ARGS``
than the port width.
Values are never truncated, regardless of the specified width.
Note that further restrictions on allowable combinations of options may apply
depending on the backend used.
For example, Verilog does not have a format specifier that allows zero-padding a
string (i.e. more than 1 ASCII character), though zero-padding a single
character is permitted.
Thus, while the RTLIL format specifier ``{8:>02c}`` translates to ``%02c``,
``{16:>02c}`` cannot be represented in Verilog and will fail to emit. In this
case, ``{16:> 02c}`` must be used, which translates to ``%2s``.

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Formal verification cells
-------------------------
.. role:: yoscrypt(code)
:language: yoscrypt
.. note::
Some front-ends may not support the generic `$check` cell, in such cases
calling :yoscrypt:`chformal -lower` will convert each `$check` cell into it's
equivalent. See `chformal` for more.
.. todo:: Describe formal cells
`$check`, `$assert`, `$assume`, `$live`, `$fair`, `$cover`, `$equiv`,
`$initstate`, `$anyconst`, `$anyseq`, `$anyinit`, `$allconst`, and `$allseq`.
Also `$ff` and `$_FF_` cells.
.. autocellgroup:: formal
:members:
:source:
:linenos:
Formal support cells
~~~~~~~~~~~~~~~~~~~~
.. autocellgroup:: formal_tag
:members:
:source:
:linenos:

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Finite state machines
---------------------
.. todo:: Describe `$fsm` cell
.. autocellgroup:: fsm
:members:
:source:
:linenos:

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Arbitrary logic functions
-------------------------
The `$lut` cell type implements a single-output LUT (lookup table). It
implements an arbitrary logic function with its ``\LUT`` parameter to map input
port ``\A`` to values of ``\Y`` output port values. In psuedocode: ``Y =
\LUT[A]``. ``\A`` has width set by parameter ``\WIDTH`` and ``\Y`` has a width
of 1. Every logic function with a single bit output has a unique `$lut`
representation.
The `$sop` cell type implements a sum-of-products expression, also known as
disjunctive normal form (DNF). It implements an arbitrary logic function. Its
structure mimics a programmable logic array (PLA). Output port ``\Y`` is the sum
of products of the bits of the input port ``\A`` as defined by parameter
``\TABLE``. ``\A`` is ``\WIDTH`` bits wide. The number of products in the sum is
set by parameter ``\DEPTH``, and each product has two bits for each input bit -
for the presence of the unnegated and negated version of said input bit in the
product. Therefore the ``\TABLE`` parameter holds ``2 * \WIDTH * \DEPTH`` bits.
For example:
Let ``\WIDTH`` be 3. We would like to represent ``\Y =~\A[0] + \A[1]~\A[2]``.
There are 2 products to be summed, so ``\DEPTH`` shall be 2.
.. code-block::
~A[2]-----+
A[2]----+|
~A[1]---+||
A[1]--+|||
~A[0]-+||||
A[0]+|||||
|||||| product formula
010000 ~\A[0]
001001 \A[1]~\A[2]
So the value of ``\TABLE`` will become ``010000001001``.
Any logic function with a single bit output can be represented with ``$sop`` but
may have variously minimized or ordered summands represented in the ``\TABLE``
values.
.. autocellgroup:: logic
:members:
:source:
:linenos:

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.. role:: verilog(code)
:language: Verilog
.. _sec:memcells:
Memories
~~~~~~~~
Memories are either represented using ``RTLIL::Memory`` objects, `$memrd_v2`,
`$memwr_v2`, and `$meminit_v2` cells, or by `$mem_v2` cells alone.
In the first alternative the ``RTLIL::Memory`` objects hold the general metadata
for the memory (bit width, size in number of words, etc.) and for each port a
`$memrd_v2` (read port) or `$memwr_v2` (write port) cell is created. Having
individual cells for read and write ports has the advantage that they can be
consolidated using resource sharing passes. In some cases this drastically
reduces the number of required ports on the memory cell. In this alternative,
memory initialization data is represented by `$meminit_v2` cells, which allow
delaying constant folding for initialization addresses and data until after the
frontend finishes.
The `$memrd_v2` cells have a clock input ``CLK``, an enable input ``EN``, an
address input ``ADDR``, a data output ``DATA``, an asynchronous reset input
``ARST``, and a synchronous reset input ``SRST``. They also have the following
parameters:
``MEMID``
The name of the ``RTLIL::Memory`` object that is associated with this read
port.
``ABITS``
The number of address bits (width of the ``ADDR`` input port).
``WIDTH``
The number of data bits (width of the ``DATA`` output port). Note that this
may be a power-of-two multiple of the underlying memory's width -- such ports
are called wide ports and access an aligned group of cells at once. In this
case, the corresponding low bits of ``ADDR`` must be tied to 0.
``CLK_ENABLE``
When this parameter is non-zero, the clock is used. Otherwise this read port
is asynchronous and the ``CLK`` input is not used.
``CLK_POLARITY``
Clock is active on the positive edge if this parameter has the value ``1'b1``
and on the negative edge if this parameter is ``1'b0``.
``TRANSPARENCY_MASK``
This parameter is a bitmask of write ports that this read port is transparent
with. The bits of this parameter are indexed by the write port's ``PORTID``
parameter. Transparency can only be enabled between synchronous ports sharing
a clock domain. When transparency is enabled for a given port pair, a read
and write to the same address in the same cycle will return the new value.
Otherwise the old value is returned.
``COLLISION_X_MASK``
This parameter is a bitmask of write ports that have undefined collision
behavior with this port. The bits of this parameter are indexed by the write
port's ``PORTID`` parameter. This behavior can only be enabled between
synchronous ports sharing a clock domain. When undefined collision is enabled
for a given port pair, a read and write to the same address in the same cycle
will return the undefined (all-X) value.This option is exclusive (for a given
port pair) with the transparency option.
``ARST_VALUE``
Whenever the ``ARST`` input is asserted, the data output will be reset to
this value. Only used for synchronous ports.
``SRST_VALUE``
Whenever the ``SRST`` input is synchronously asserted, the data output will
be reset to this value. Only used for synchronous ports.
``INIT_VALUE``
The initial value of the data output, for synchronous ports.
``CE_OVER_SRST``
If this parameter is non-zero, the ``SRST`` input is only recognized when
``EN`` is true. Otherwise, ``SRST`` is recognized regardless of ``EN``.
The `$memwr_v2` cells have a clock input ``CLK``, an enable input ``EN`` (one
enable bit for each data bit), an address input ``ADDR`` and a data input
``DATA``. They also have the following parameters:
``MEMID``
The name of the ``RTLIL::Memory`` object that is associated with this write
port.
``ABITS``
The number of address bits (width of the ``ADDR`` input port).
``WIDTH``
The number of data bits (width of the ``DATA`` output port). Like with
`$memrd_v2` cells, the width is allowed to be any power-of-two multiple of
memory width, with the corresponding restriction on address.
``CLK_ENABLE``
When this parameter is non-zero, the clock is used. Otherwise this write port
is asynchronous and the ``CLK`` input is not used.
``CLK_POLARITY``
Clock is active on positive edge if this parameter has the value ``1'b1`` and
on the negative edge if this parameter is ``1'b0``.
``PORTID``
An identifier for this write port, used to index write port bit mask
parameters.
``PRIORITY_MASK``
This parameter is a bitmask of write ports that this write port has priority
over in case of writing to the same address. The bits of this parameter are
indexed by the other write port's ``PORTID`` parameter. Write ports can only
have priority over write ports with lower port ID. When two ports write to
the same address and neither has priority over the other, the result is
undefined. Priority can only be set between two synchronous ports sharing
the same clock domain.
The `$meminit_v2` cells have an address input ``ADDR``, a data input ``DATA``,
with the width of the ``DATA`` port equal to ``WIDTH`` parameter times ``WORDS``
parameter, and a bit enable mask input ``EN`` with width equal to ``WIDTH``
parameter. All three of the inputs must resolve to a constant for synthesis to
succeed.
``MEMID``
The name of the ``RTLIL::Memory`` object that is associated with this
initialization cell.
``ABITS``
The number of address bits (width of the ``ADDR`` input port).
``WIDTH``
The number of data bits per memory location.
``WORDS``
The number of consecutive memory locations initialized by this cell.
``PRIORITY``
The cell with the higher integer value in this parameter wins an
initialization conflict.
The HDL frontend models a memory using ``RTLIL::Memory`` objects and
asynchronous `$memrd_v2` and `$memwr_v2` cells. The `memory` pass (i.e. its
various sub-passes) migrates `$dff` cells into the `$memrd_v2` and `$memwr_v2`
cells making them synchronous, then converts them to a single `$mem_v2` cell and
(optionally) maps this cell type to `$dff` cells for the individual words and
multiplexer-based address decoders for the read and write interfaces. When the
last step is disabled or not possible, a `$mem_v2` cell is left in the design.
The `$mem_v2` cell provides the following parameters:
``MEMID``
The name of the original ``RTLIL::Memory`` object that became this `$mem_v2`
cell.
``SIZE``
The number of words in the memory.
``ABITS``
The number of address bits.
``WIDTH``
The number of data bits per word.
``INIT``
The initial memory contents.
``RD_PORTS``
The number of read ports on this memory cell.
``RD_WIDE_CONTINUATION``
This parameter is ``RD_PORTS`` bits wide, containing a bitmask of "wide
continuation" read ports. Such ports are used to represent the extra data
bits of wide ports in the combined cell, and must have all control signals
identical with the preceding port, except for address, which must have the
proper sub-cell address encoded in the low bits.
``RD_CLK_ENABLE``
This parameter is ``RD_PORTS`` bits wide, containing a clock enable bit for
each read port.
``RD_CLK_POLARITY``
This parameter is ``RD_PORTS`` bits wide, containing a clock polarity bit for
each read port.
``RD_TRANSPARENCY_MASK``
This parameter is ``RD_PORTS*WR_PORTS`` bits wide, containing a concatenation
of all ``TRANSPARENCY_MASK`` values of the original `$memrd_v2` cells.
``RD_COLLISION_X_MASK``
This parameter is ``RD_PORTS*WR_PORTS`` bits wide, containing a concatenation
of all ``COLLISION_X_MASK`` values of the original `$memrd_v2` cells.
``RD_CE_OVER_SRST``
This parameter is ``RD_PORTS`` bits wide, determining relative synchronous
reset and enable priority for each read port.
``RD_INIT_VALUE``
This parameter is ``RD_PORTS*WIDTH`` bits wide, containing the initial value
for each synchronous read port.
``RD_ARST_VALUE``
This parameter is ``RD_PORTS*WIDTH`` bits wide, containing the asynchronous
reset value for each synchronous read port.
``RD_SRST_VALUE``
This parameter is ``RD_PORTS*WIDTH`` bits wide, containing the synchronous
reset value for each synchronous read port.
``WR_PORTS``
The number of write ports on this memory cell.
``WR_WIDE_CONTINUATION``
This parameter is ``WR_PORTS`` bits wide, containing a bitmask of "wide
continuation" write ports.
``WR_CLK_ENABLE``
This parameter is ``WR_PORTS`` bits wide, containing a clock enable bit for
each write port.
``WR_CLK_POLARITY``
This parameter is ``WR_PORTS`` bits wide, containing a clock polarity bit for
each write port.
``WR_PRIORITY_MASK``
This parameter is ``WR_PORTS*WR_PORTS`` bits wide, containing a concatenation
of all ``PRIORITY_MASK`` values of the original `$memwr_v2` cells.
The `$mem_v2` cell has the following ports:
``RD_CLK``
This input is ``RD_PORTS`` bits wide, containing all clock signals for the
read ports.
``RD_EN``
This input is ``RD_PORTS`` bits wide, containing all enable signals for the
read ports.
``RD_ADDR``
This input is ``RD_PORTS*ABITS`` bits wide, containing all address signals
for the read ports.
``RD_DATA``
This output is ``RD_PORTS*WIDTH`` bits wide, containing all data signals for
the read ports.
``RD_ARST``
This input is ``RD_PORTS`` bits wide, containing all asynchronous reset
signals for the read ports.
``RD_SRST``
This input is ``RD_PORTS`` bits wide, containing all synchronous reset
signals for the read ports.
``WR_CLK``
This input is ``WR_PORTS`` bits wide, containing all clock signals for the
write ports.
``WR_EN``
This input is ``WR_PORTS*WIDTH`` bits wide, containing all enable signals for
the write ports.
``WR_ADDR``
This input is ``WR_PORTS*ABITS`` bits wide, containing all address signals
for the write ports.
``WR_DATA``
This input is ``WR_PORTS*WIDTH`` bits wide, containing all data signals for
the write ports.
The `memory_collect` pass can be used to convert discrete `$memrd_v2`,
`$memwr_v2`, and `$meminit_v2` cells belonging to the same memory to a single
`$mem_v2` cell, whereas the `memory_unpack` pass performs the inverse operation.
The `memory_dff` pass can combine asynchronous memory ports that are fed by or
feeding registers into synchronous memory ports. The `memory_bram` pass can be
used to recognize `$mem_v2` cells that can be implemented with a block RAM
resource on an FPGA. The `memory_map` pass can be used to implement `$mem_v2`
cells as basic logic: word-wide DFFs and address decoders.
.. autocellgroup:: mem
:members:
:source:
:linenos:

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@ -0,0 +1,47 @@
.. role:: verilog(code)
:language: Verilog
Multiplexers
------------
Multiplexers are generated by the Verilog HDL frontend for ``?:``-expressions.
Multiplexers are also generated by the proc pass to map the decision trees from
RTLIL::Process objects to logic.
The simplest multiplexer cell type is `$mux`. Cells of this type have a
``WITDH`` parameter and data inputs ``A`` and ``B`` and a data output ``Y``, all
of the specified width. This cell also has a single bit control input ``S``. If
``S`` is 0 the value from the input ``A`` is sent to the output, if it is 1 the
value from the ``B`` input is sent to the output. So the `$mux` cell implements
the function :verilog:`Y = S ? B : A`.
The `$pmux` cell is used to multiplex between many inputs using a one-hot select
signal. Cells of this type have a ``WIDTH`` and a ``S_WIDTH`` parameter and
inputs ``A``, ``B``, and ``S`` and an output ``Y``. The ``S`` input is
``S_WIDTH`` bits wide. The ``A`` input and the output are both ``WIDTH`` bits
wide and the ``B`` input is ``WIDTH*S_WIDTH`` bits wide. When all bits of ``S``
are zero, the value from ``A`` input is sent to the output. If the :math:`n`\
'th bit from ``S`` is set, the value :math:`n`\ 'th ``WIDTH`` bits wide slice of
the ``B`` input is sent to the output. When more than one bit from ``S`` is set
the output is undefined. Cells of this type are used to model "parallel cases"
(defined by using the ``parallel_case`` attribute or detected by an
optimization).
The `$tribuf` cell is used to implement tristate logic. Cells of this type have
a ``WIDTH`` parameter and inputs ``A`` and ``EN`` and an output ``Y``. The ``A``
input and ``Y`` output are ``WIDTH`` bits wide, and the ``EN`` input is one bit
wide. When ``EN`` is 0, the output is not driven. When ``EN`` is 1, the value
from ``A`` input is sent to the ``Y`` output. Therefore, the `$tribuf` cell
implements the function :verilog:`Y = EN ? A : 'bz`.
Behavioural code with cascaded if-then-else- and case-statements usually results
in trees of multiplexer cells. Many passes (from various optimizations to FSM
extraction) heavily depend on these multiplexer trees to understand dependencies
between signals. Therefore optimizations should not break these multiplexer
trees (e.g. by replacing a multiplexer between a calculated signal and a
constant zero with an `$and` gate).
.. autocellgroup:: mux
:members:
:source:
:linenos:

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@ -0,0 +1,124 @@
.. role:: verilog(code)
:language: Verilog
Registers
---------
SR-type latches are represented by `$sr` cells. These cells have input ports
``SET`` and ``CLR`` and an output port ``Q``. They have the following
parameters:
``WIDTH``
The width of inputs ``SET`` and ``CLR`` and output ``Q``.
``SET_POLARITY``
The set input bits are active-high if this parameter has the value ``1'b1``
and active-low if this parameter is ``1'b0``.
``CLR_POLARITY``
The reset input bits are active-high if this parameter has the value ``1'b1``
and active-low if this parameter is ``1'b0``.
Both set and reset inputs have separate bits for every output bit. When both the
set and reset inputs of an `$sr` cell are active for a given bit index, the
reset input takes precedence.
D-type flip-flops are represented by `$dff` cells. These cells have a clock port
``CLK``, an input port ``D`` and an output port ``Q``. The following parameters
are available for `$dff` cells:
``WIDTH``
The width of input ``D`` and output ``Q``.
``CLK_POLARITY``
Clock is active on the positive edge if this parameter has the value ``1'b1``
and on the negative edge if this parameter is ``1'b0``.
D-type flip-flops with asynchronous reset are represented by `$adff` cells. As
the `$dff` cells they have ``CLK``, ``D`` and ``Q`` ports. In addition they also
have a single-bit ``ARST`` input port for the reset pin and the following
additional two parameters:
``ARST_POLARITY``
The asynchronous reset is active-high if this parameter has the value
``1'b1`` and active-low if this parameter is ``1'b0``.
``ARST_VALUE``
The state of ``Q`` will be set to this value when the reset is active.
Usually these cells are generated by the `proc` pass using the information in
the designs RTLIL::Process objects.
D-type flip-flops with synchronous reset are represented by `$sdff` cells. As
the `$dff` cells they have ``CLK``, ``D`` and ``Q`` ports. In addition they also
have a single-bit ``SRST`` input port for the reset pin and the following
additional two parameters:
``SRST_POLARITY``
The synchronous reset is active-high if this parameter has the value ``1'b1``
and active-low if this parameter is ``1'b0``.
``SRST_VALUE``
The state of ``Q`` will be set to this value when the reset is active.
Note that the `$adff` and `$sdff` cells can only be used when the reset value is
constant.
D-type flip-flops with asynchronous load are represented by `$aldff` cells. As
the `$dff` cells they have ``CLK``, ``D`` and ``Q`` ports. In addition they also
have a single-bit ``ALOAD`` input port for the async load enable pin, a ``AD``
input port with the same width as data for the async load data, and the
following additional parameter:
``ALOAD_POLARITY``
The asynchronous load is active-high if this parameter has the value ``1'b1``
and active-low if this parameter is ``1'b0``.
D-type flip-flops with asynchronous set and reset are represented by `$dffsr`
cells. As the `$dff` cells they have ``CLK``, ``D`` and ``Q`` ports. In addition
they also have multi-bit ``SET`` and ``CLR`` input ports and the corresponding
polarity parameters, like `$sr` cells.
D-type flip-flops with enable are represented by `$dffe`, `$adffe`, `$aldffe`,
`$dffsre`, `$sdffe`, and `$sdffce` cells, which are enhanced variants of `$dff`,
`$adff`, `$aldff`, `$dffsr`, `$sdff` (with reset over enable) and `$sdff` (with
enable over reset) cells, respectively. They have the same ports and parameters
as their base cell. In addition they also have a single-bit ``EN`` input port
for the enable pin and the following parameter:
``EN_POLARITY``
The enable input is active-high if this parameter has the value ``1'b1`` and
active-low if this parameter is ``1'b0``.
D-type latches are represented by `$dlatch` cells. These cells have an enable
port ``EN``, an input port ``D``, and an output port ``Q``. The following
parameters are available for `$dlatch` cells:
``WIDTH``
The width of input ``D`` and output ``Q``.
``EN_POLARITY``
The enable input is active-high if this parameter has the value ``1'b1`` and
active-low if this parameter is ``1'b0``.
The latch is transparent when the ``EN`` input is active.
D-type latches with reset are represented by `$adlatch` cells. In addition to
`$dlatch` ports and parameters, they also have a single-bit ``ARST`` input port
for the reset pin and the following additional parameters:
``ARST_POLARITY``
The asynchronous reset is active-high if this parameter has the value
``1'b1`` and active-low if this parameter is ``1'b0``.
``ARST_VALUE``
The state of ``Q`` will be set to this value when the reset is active.
D-type latches with set and reset are represented by `$dlatchsr` cells. In
addition to `$dlatch` ports and parameters, they also have multi-bit ``SET`` and
``CLR`` input ports and the corresponding polarity parameters, like `$sr` cells.
.. autocellgroup:: reg
:members:
:source:
:linenos:

9
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@ -0,0 +1,9 @@
Specify rules
-------------
.. todo:: `$specify2`, `$specify3`, and `$specrule` cells.
.. autocellgroup:: spec
:members:
:source:
:linenos:

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@ -0,0 +1,50 @@
.. role:: verilog(code)
:language: Verilog
Unary operators
---------------
All unary RTL cells have one input port ``A`` and one output port ``Y``. They
also have the following parameters:
``A_SIGNED``
Set to a non-zero value if the input ``A`` is signed and therefore should be
sign-extended when needed.
``A_WIDTH``
The width of the input port ``A``.
``Y_WIDTH``
The width of the output port ``Y``.
.. table:: Cell types for unary operators with their corresponding Verilog expressions.
================== ==============
Verilog Cell Type
================== ==============
:verilog:`Y = ~A` `$not`
:verilog:`Y = +A` `$pos`
:verilog:`Y = -A` `$neg`
:verilog:`Y = &A` `$reduce_and`
:verilog:`Y = |A` `$reduce_or`
:verilog:`Y = ^A` `$reduce_xor`
:verilog:`Y = ~^A` `$reduce_xnor`
:verilog:`Y = |A` `$reduce_bool`
:verilog:`Y = !A` `$logic_not`
================== ==============
For the unary cells that output a logical value (`$reduce_and`, `$reduce_or`,
`$reduce_xor`, `$reduce_xnor`, `$reduce_bool`, `$logic_not`), when the
``Y_WIDTH`` parameter is greater than 1, the output is zero-extended, and only
the least significant bit varies.
Note that `$reduce_or` and `$reduce_bool` generally represent the same logic
function. But the `read_verilog` frontend will generate them in different
situations. A `$reduce_or` cell is generated when the prefix ``|`` operator is
being used. A `$reduce_bool` cell is generated when a bit vector is used as a
condition in an ``if``-statement or ``?:``-expression.
.. autocellgroup:: unary
:members:
:source:
:linenos:

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@ -0,0 +1,9 @@
Wire cells
-------------------------
.. todo:: Add information about `$slice` and `$concat` cells.
.. autocellgroup:: wire
:members:
:source:
:linenos:

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@ -0,0 +1,15 @@
Internal cell library
=====================
The intermediate language used by Yosys (RTLIL) represents logic and memory with
a series of cells. This section provides details for those cells, breaking them
down into two major categories: coarse-grain word-level cells; and fine-grain
gate-level cells. An additional section contains a list of properties which may
be shared across multiple cells.
.. toctree::
:maxdepth: 2
/cell/index_word
/cell/index_gate
/cell/properties

4
docs/source/code_examples/extensions/Makefile
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@ -4,8 +4,8 @@ YOSYS ?= ../../../../$(PROGRAM_PREFIX)yosys
.PHONY: all dots examples
all: dots examples
dots: test1.dot
examples: test0.log test1.log test2.log
dots: test1.dot my_cmd.so
examples: test0.log test1.log test2.log my_cmd.so
CXXFLAGS=$(shell $(YOSYS)-config --cxxflags)
DATDIR=$(shell $(YOSYS)-config --datdir)

2
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@ -0,0 +1,2 @@
*.out
*.stat

50
docs/source/conf.py
View file

@ -1,4 +1,5 @@
#!/usr/bin/env python3
from pathlib import Path
import sys
import os
@ -8,39 +9,18 @@ copyright ='2024 YosysHQ GmbH'
yosys_ver = "0.46"
# select HTML theme
html_theme = 'furo'
templates_path = ["_templates"]
html_logo = '_static/logo.png'
html_favicon = '_static/favico.png'
html_css_files = ['yosyshq.css', 'custom.css']
html_theme_options = {
"sidebar_hide_name": True,
"light_css_variables": {
"color-brand-primary": "#d6368f",
"color-brand-content": "#4b72b8",
"color-api-name": "#8857a3",
"color-api-pre-name": "#4b72b8",
"color-link": "#8857a3",
},
"dark_css_variables": {
"color-brand-primary": "#e488bb",
"color-brand-content": "#98bdff",
"color-api-name": "#8857a3",
"color-api-pre-name": "#4b72b8",
"color-link": "#be95d5",
},
}
html_theme = 'furo-ys'
html_css_files = ['custom.css']
# These folders are copied to the documentation's HTML output
html_static_path = ['_static', "_images"]
# code blocks style
pygments_style = 'colorful'
# default to no highlight
highlight_language = 'none'
# default single quotes to attempt auto reference, or fallback to code
default_role = 'autoref'
extensions = ['sphinx.ext.autosectionlabel', 'sphinxcontrib.bibtex']
if os.getenv("READTHEDOCS"):
@ -97,9 +77,15 @@ latex_elements = {
sys.path += [os.path.dirname(__file__) + "/../"]
extensions.append('util.cmdref')
def setup(sphinx):
from util.RtlilLexer import RtlilLexer
sphinx.add_lexer("RTLIL", RtlilLexer)
# use autodocs
extensions.append('sphinx.ext.autodoc')
extensions.append('util.cellref')
cells_json = Path(__file__).parent / 'generated' / 'cells.json'
from util.YoscryptLexer import YoscryptLexer
sphinx.add_lexer("yoscrypt", YoscryptLexer)
from sphinx.application import Sphinx
def setup(app: Sphinx) -> None:
from util.RtlilLexer import RtlilLexer
app.add_lexer("RTLIL", RtlilLexer)
from furo_ys.lexers.YoscryptLexer import YoscryptLexer
app.add_lexer("yoscrypt", YoscryptLexer)

394
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@ -2,13 +2,12 @@ Synthesis starter
-----------------
This page will be a guided walkthrough of the prepackaged iCE40 FPGA synthesis
script - :cmd:ref:`synth_ice40`. We will take a simple design through each
step, looking at the commands being called and what they do to the design. While
:cmd:ref:`synth_ice40` is specific to the iCE40 platform, most of the operations
we will be discussing are common across the majority of FPGA synthesis scripts.
Thus, this document will provide a good foundational understanding of how
synthesis in Yosys is performed, regardless of the actual architecture being
used.
script - `synth_ice40`. We will take a simple design through each step, looking
at the commands being called and what they do to the design. While `synth_ice40`
is specific to the iCE40 platform, most of the operations we will be discussing
are common across the majority of FPGA synthesis scripts. Thus, this document
will provide a good foundational understanding of how synthesis in Yosys is
performed, regardless of the actual architecture being used.
.. seealso:: Advanced usage docs for
:doc:`/using_yosys/synthesis/synth`
@ -59,8 +58,8 @@ can run each of the commands individually for a better sense of how each part
contributes to the flow. We will also start with just a single module;
``addr_gen``.
At the bottom of the :cmd:ref:`help` output for
:cmd:ref:`synth_ice40` is the complete list of commands called by this script.
At the bottom of the `help` output for
`synth_ice40` is the complete list of commands called by this script.
Let's start with the section labeled ``begin``:
.. literalinclude:: /cmd/synth_ice40.rst
@ -105,10 +104,10 @@ Since we're just getting started, let's instead begin with :yoscrypt:`hierarchy
.. note::
:cmd:ref:`hierarchy` should always be the first command after the design has
been read. By specifying the top module, :cmd:ref:`hierarchy` will also set
the ``(* top *)`` attribute on it. This is used by other commands that need
to know which module is the top.
`hierarchy` should always be the first command after the design has been
read. By specifying the top module, `hierarchy` will also set the ``(* top
*)`` attribute on it. This is used by other commands that need to know which
module is the top.
.. use doscon for a console-like display that supports the `yosys> [command]` format.
@ -125,24 +124,24 @@ Our ``addr_gen`` circuit now looks like this:
:class: width-helper invert-helper
:name: addr_gen_hier
``addr_gen`` module after :cmd:ref:`hierarchy`
``addr_gen`` module after `hierarchy`
Simple operations like ``addr + 1`` and ``addr == MAX_DATA-1`` can be extracted
from our ``always @`` block in :ref:`addr_gen-v`. This gives us the highlighted
``$add`` and ``$eq`` cells we see. But control logic (like the ``if .. else``)
and memory elements (like the ``addr <= 0``) are not so straightforward. These
get put into "processes", shown in the schematic as ``PROC``. Note how the
second line refers to the line numbers of the start/end of the corresponding
``always @`` block. In the case of an ``initial`` block, we instead see the
``PROC`` referring to line 0.
`$add` and `$eq` cells we see. But control logic (like the ``if .. else``) and
memory elements (like the ``addr <= 0``) are not so straightforward. These get
put into "processes", shown in the schematic as ``PROC``. Note how the second
line refers to the line numbers of the start/end of the corresponding ``always
@`` block. In the case of an ``initial`` block, we instead see the ``PROC``
referring to line 0.
To handle these, let us now introduce the next command: :doc:`/cmd/proc`.
:cmd:ref:`proc` is a macro command like :cmd:ref:`synth_ice40`. Rather than
modifying the design directly, it instead calls a series of other commands. In
the case of :cmd:ref:`proc`, these sub-commands work to convert the behavioral
logic of processes into multiplexers and registers. Let's see what happens when
we run it. For now, we will call :yoscrypt:`proc -noopt` to prevent some
automatic optimizations which would normally happen.
To handle these, let us now introduce the next command: :doc:`/cmd/proc`. `proc`
is a macro command like `synth_ice40`. Rather than modifying the design
directly, it instead calls a series of other commands. In the case of `proc`,
these sub-commands work to convert the behavioral logic of processes into
multiplexers and registers. Let's see what happens when we run it. For now, we
will call :yoscrypt:`proc -noopt` to prevent some automatic optimizations which
would normally happen.
.. figure:: /_images/code_examples/fifo/addr_gen_proc.*
:class: width-helper invert-helper
@ -151,19 +150,18 @@ automatic optimizations which would normally happen.
``addr_gen`` module after :yoscrypt:`proc -noopt`
There are now a few new cells from our ``always @``, which have been
highlighted. The ``if`` statements are now modeled with ``$mux`` cells, while
the register uses an ``$adff`` cell. If we look at the terminal output we can
also see all of the different ``proc_*`` commands being called. We will look at
each of these in more detail in :doc:`/using_yosys/synthesis/proc`.
highlighted. The ``if`` statements are now modeled with `$mux` cells, while the
register uses an `$adff` cell. If we look at the terminal output we can also
see all of the different ``proc_*`` commands being called. We will look at each
of these in more detail in :doc:`/using_yosys/synthesis/proc`.
Notice how in the top left of :ref:`addr_gen_proc` we have a floating wire,
generated from the initial assignment of 0 to the ``addr`` wire. However, this
initial assignment is not synthesizable, so this will need to be cleaned up
before we can generate the physical hardware. We can do this now by calling
:cmd:ref:`clean`. We're also going to call :cmd:ref:`opt_expr` now, which would
normally be called at the end of :cmd:ref:`proc`. We can call both commands at
the same time by separating them with a colon and space: :yoscrypt:`opt_expr;
clean`.
`clean`. We're also going to call `opt_expr` now, which would normally be
called at the end of `proc`. We can call both commands at the same time by
separating them with a colon and space: :yoscrypt:`opt_expr; clean`.
.. figure:: /_images/code_examples/fifo/addr_gen_clean.*
:class: width-helper invert-helper
@ -171,24 +169,24 @@ clean`.
``addr_gen`` module after :yoscrypt:`opt_expr; clean`
You may also notice that the highlighted ``$eq`` cell input of ``255`` has
changed to ``8'11111111``. Constant values are presented in the format
You may also notice that the highlighted `$eq` cell input of ``255`` has changed
to ``8'11111111``. Constant values are presented in the format
``<bit_width>'<bits>``, with 32-bit values instead using the decimal number.
This indicates that the constant input has been reduced from 32-bit wide to
8-bit wide. This is a side-effect of running :cmd:ref:`opt_expr`, which
performs constant folding and simple expression rewriting. For more on why
this happens, refer to :doc:`/using_yosys/synthesis/opt` and the :ref:`section
on opt_expr <adv_opt_expr>`.
8-bit wide. This is a side-effect of running `opt_expr`, which performs
constant folding and simple expression rewriting. For more on why this
happens, refer to :doc:`/using_yosys/synthesis/opt` and the :ref:`section on
opt_expr <adv_opt_expr>`.
.. note::
:doc:`/cmd/clean` can also be called with two semicolons after any command,
for example we could have called :yoscrypt:`opt_expr;;` instead of
:yoscrypt:`opt_expr; clean`. You may notice some scripts will end each line
with ``;;``. It is beneficial to run :cmd:ref:`clean` before inspecting
intermediate products to remove disconnected parts of the circuit which have
been left over, and in some cases can reduce the processing required in
subsequent commands.
with ``;;``. It is beneficial to run `clean` before inspecting intermediate
products to remove disconnected parts of the circuit which have been left
over, and in some cases can reduce the processing required in subsequent
commands.
.. todo:: consider a brief glossary for terms like adff
@ -202,8 +200,8 @@ The full example
Let's now go back and check on our full design by using :yoscrypt:`hierarchy
-check -top fifo`. By passing the ``-check`` option there we are also telling
the :cmd:ref:`hierarchy` command that if the design includes any non-blackbox
modules without an implementation it should return an error.
the `hierarchy` command that if the design includes any non-blackbox modules
without an implementation it should return an error.
Note that if we tried to run this command now then we would get an error. This
is because we already removed all of the modules other than ``addr_gen``. We
@ -218,18 +216,17 @@ could restart our shell session, but instead let's use two new commands:
:end-before: yosys> proc
:caption: reloading :file:`fifo.v` and running :yoscrypt:`hierarchy -check -top fifo`
Notice how this time we didn't see any of those `$abstract` modules? That's
Notice how this time we didn't see any of those ``$abstract`` modules? That's
because when we ran ``yosys fifo.v``, the first command Yosys called was
:yoscrypt:`read_verilog -defer fifo.v`. The ``-defer`` option there tells
:cmd:ref:`read_verilog` only read the abstract syntax tree and defer actual
compilation to a later :cmd:ref:`hierarchy` command. This is useful in cases
where the default parameters of modules yield invalid code which is not
synthesizable. This is why Yosys defers compilation automatically and is one of
the reasons why hierarchy should always be the first command after loading the
design. If we know that our design won't run into this issue, we can skip the
``-defer``.
`read_verilog` only read the abstract syntax tree and defer actual compilation
to a later `hierarchy` command. This is useful in cases where the default
parameters of modules yield invalid code which is not synthesizable. This is why
Yosys defers compilation automatically and is one of the reasons why hierarchy
should always be the first command after loading the design. If we know that
our design won't run into this issue, we can skip the ``-defer``.
.. todo:: :cmd:ref:`hierarchy` failure modes
.. todo:: `hierarchy` failure modes
.. note::
@ -243,19 +240,19 @@ design. If we know that our design won't run into this issue, we can skip the
interactive terminal. :kbd:`ctrl+c` (i.e. SIGINT) will also end the terminal
session but will return an error code rather than exiting gracefully.
We can also run :cmd:ref:`proc` now to finish off the full :ref:`synth_begin`.
Because the design schematic is quite large, we will be showing just the data
path for the ``rdata`` output. If you would like to see the entire design for
yourself, you can do so with :doc:`/cmd/show`. Note that the :cmd:ref:`show`
command only works with a single module, so you may need to call it with
:yoscrypt:`show fifo`. :ref:`show_intro` section in
:doc:`/getting_started/scripting_intro` has more on how to use :cmd:ref:`show`.
We can also run `proc` now to finish off the full :ref:`synth_begin`. Because
the design schematic is quite large, we will be showing just the data path for
the ``rdata`` output. If you would like to see the entire design for yourself,
you can do so with :doc:`/cmd/show`. Note that the `show` command only works
with a single module, so you may need to call it with :yoscrypt:`show fifo`.
:ref:`show_intro` section in :doc:`/getting_started/scripting_intro` has more on
how to use `show`.
.. figure:: /_images/code_examples/fifo/rdata_proc.*
:class: width-helper invert-helper
:name: rdata_proc
``rdata`` output after :cmd:ref:`proc`
``rdata`` output after `proc`
The highlighted ``fifo_reader`` block contains an instance of the
:ref:`addr_gen_proc` that we looked at earlier. Notice how the type is shown as
@ -263,10 +260,10 @@ The highlighted ``fifo_reader`` block contains an instance of the
instance of the ``addr_gen`` module with the ``MAX_DATA`` parameter set to the
given value.
The other highlighted block is a ``$memrd`` cell. At this stage of synthesis we
The other highlighted block is a `$memrd` cell. At this stage of synthesis we
don't yet know what type of memory is going to be implemented, but we *do* know
that ``rdata <= data[raddr];`` could be implemented as a read from memory. Note
that the ``$memrd`` cell here is asynchronous, with both the clock and enable
that the `$memrd` cell here is asynchronous, with both the clock and enable
signal undefined; shown with the ``1'x`` inputs.
.. seealso:: Advanced usage docs for
@ -276,7 +273,7 @@ Flattening
~~~~~~~~~~
At this stage of a synthesis flow there are a few other commands we could run.
In :cmd:ref:`synth_ice40` we get these:
In `synth_ice40` we get these:
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -286,7 +283,7 @@ In :cmd:ref:`synth_ice40` we get these:
:name: synth_flatten
:caption: ``flatten`` section
First off is :cmd:ref:`flatten`. Flattening the design like this can allow for
First off is `flatten`. Flattening the design like this can allow for
optimizations between modules which would otherwise be missed. Let's run
:yoscrypt:`flatten;;` on our design.
@ -309,23 +306,22 @@ optimizations between modules which would otherwise be missed. Let's run
The pieces have moved around a bit, but we can see :ref:`addr_gen_proc` from
earlier has replaced the ``fifo_reader`` block in :ref:`rdata_proc`. We can
also see that the ``addr`` output has been renamed to :file:`fifo_reader.addr`
and merged with the ``raddr`` wire feeding into the ``$memrd`` cell. This wire
merging happened during the call to :cmd:ref:`clean` which we can see in the
and merged with the ``raddr`` wire feeding into the `$memrd` cell. This wire
merging happened during the call to `clean` which we can see in the
:ref:`flat_clean`.
.. note::
:cmd:ref:`flatten` and :cmd:ref:`clean` would normally be combined into a
`flatten` and `clean` would normally be combined into a
single :yoterm:`yosys> flatten;;` output, but they appear separately here as
a side effect of using :cmd:ref:`echo` for generating the terminal style
a side effect of using `echo` for generating the terminal style
output.
Depending on the target architecture, this stage of synthesis might also see
commands such as :cmd:ref:`tribuf` with the ``-logic`` option and
:cmd:ref:`deminout`. These remove tristate and inout constructs respectively,
replacing them with logic suitable for mapping to an FPGA. Since we do not have
any such constructs in our example running these commands does not change our
design.
commands such as `tribuf` with the ``-logic`` option and `deminout`. These
remove tristate and inout constructs respectively, replacing them with logic
suitable for mapping to an FPGA. Since we do not have any such constructs in
our example running these commands does not change our design.
The coarse-grain representation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -342,9 +338,9 @@ optimizations and other transformations done previously.
.. note::
While the iCE40 flow had a :ref:`synth_flatten` and put :cmd:ref:`proc` in
the :ref:`synth_begin`, some synthesis scripts will instead include these in
this section.
While the iCE40 flow had a :ref:`synth_flatten` and put `proc` in the
:ref:`synth_begin`, some synthesis scripts will instead include these in this
section.
Part 1
^^^^^^
@ -359,36 +355,35 @@ In the iCE40 flow, we start with the following commands:
:caption: ``coarse`` section (part 1)
:name: synth_coarse1
We've already come across :cmd:ref:`opt_expr`, and :cmd:ref:`opt_clean` is the
same as :cmd:ref:`clean` but with more verbose output. The :cmd:ref:`check`
pass identifies a few obvious problems which will cause errors later. Calling
it here lets us fail faster rather than wasting time on something we know is
impossible.
We've already come across `opt_expr`, and `opt_clean` is the same as `clean` but
with more verbose output. The `check` pass identifies a few obvious problems
which will cause errors later. Calling it here lets us fail faster rather than
wasting time on something we know is impossible.
Next up is :yoscrypt:`opt -nodffe -nosdff` performing a set of simple
optimizations on the design. This command also ensures that only a specific
subset of FF types are included, in preparation for the next command:
:doc:`/cmd/fsm`. Both :cmd:ref:`opt` and :cmd:ref:`fsm` are macro commands
which are explored in more detail in :doc:`/using_yosys/synthesis/opt` and
:doc:`/cmd/fsm`. Both `opt` and `fsm` are macro commands which are explored in
more detail in :doc:`/using_yosys/synthesis/opt` and
:doc:`/using_yosys/synthesis/fsm` respectively.
Up until now, the data path for ``rdata`` has remained the same since
:ref:`rdata_flat`. However the next call to :cmd:ref:`opt` does cause a change.
Specifically, the call to :cmd:ref:`opt_dff` without the ``-nodffe -nosdff``
options is able to fold one of the ``$mux`` cells into the ``$adff`` to form an
``$adffe`` cell; highlighted below:
:ref:`rdata_flat`. However the next call to `opt` does cause a change.
Specifically, the call to `opt_dff` without the ``-nodffe -nosdff`` options is
able to fold one of the `$mux` cells into the `$adff` to form an `$adffe` cell;
highlighted below:
.. literalinclude:: /code_examples/fifo/fifo.out
:language: doscon
:start-at: yosys> opt_dff
:end-before: yosys> select
:caption: output of :cmd:ref:`opt_dff`
:caption: output of `opt_dff`
.. figure:: /_images/code_examples/fifo/rdata_adffe.*
:class: width-helper invert-helper
:name: rdata_adffe
``rdata`` output after :cmd:ref:`opt_dff`
``rdata`` output after `opt_dff`
.. seealso:: Advanced usage docs for
@ -414,27 +409,27 @@ First up is :doc:`/cmd/wreduce`. If we run this we get the following:
:language: doscon
:start-at: yosys> wreduce
:end-before: yosys> select
:caption: output of :cmd:ref:`wreduce`
:caption: output of `wreduce`
Looking at the data path for ``rdata``, the most relevant of these width
reductions are the ones affecting ``fifo.$flatten\fifo_reader.$add$fifo.v``.
That is the ``$add`` cell incrementing the fifo_reader address. We can look at
That is the `$add` cell incrementing the fifo_reader address. We can look at
the schematic and see the output of that cell has now changed.
.. todo:: pending bugfix in :cmd:ref:`wreduce` and/or :cmd:ref:`opt_clean`
.. todo:: pending bugfix in `wreduce` and/or `opt_clean`
.. figure:: /_images/code_examples/fifo/rdata_wreduce.*
:class: width-helper invert-helper
:name: rdata_wreduce
``rdata`` output after :cmd:ref:`wreduce`
``rdata`` output after `wreduce`
The next two (new) commands are :doc:`/cmd/peepopt` and :doc:`/cmd/share`.
Neither of these affect our design, and they're explored in more detail in
:doc:`/using_yosys/synthesis/opt`, so let's skip over them. :yoscrypt:`techmap
-map +/cmp2lut.v -D LUT_WIDTH=4` optimizes certain comparison operators by
converting them to LUTs instead. The usage of :cmd:ref:`techmap` is explored
more in :doc:`/using_yosys/synthesis/techmap_synth`.
converting them to LUTs instead. The usage of `techmap` is explored more in
:doc:`/using_yosys/synthesis/techmap_synth`.
Our next command to run is
:doc:`/cmd/memory_dff`.
@ -443,17 +438,17 @@ Our next command to run is
:language: doscon
:start-at: yosys> memory_dff
:end-before: yosys> select
:caption: output of :cmd:ref:`memory_dff`
:caption: output of `memory_dff`
.. figure:: /_images/code_examples/fifo/rdata_memrdv2.*
:class: width-helper invert-helper
:name: rdata_memrdv2
``rdata`` output after :cmd:ref:`memory_dff`
``rdata`` output after `memory_dff`
As the title suggests, :cmd:ref:`memory_dff` has merged the output ``$dff`` into
the ``$memrd`` cell and converted it to a ``$memrd_v2`` (highlighted). This has
also connected the ``CLK`` port to the ``clk`` input as it is now a synchronous
As the title suggests, `memory_dff` has merged the output `$dff` into the
`$memrd` cell and converted it to a `$memrd_v2` (highlighted). This has also
connected the ``CLK`` port to the ``clk`` input as it is now a synchronous
memory read with appropriate enable (``EN=1'1``) and reset (``ARST=1'0`` and
``SRST=1'0``) inputs.
@ -466,12 +461,11 @@ memory read with appropriate enable (``EN=1'1``) and reset (``ARST=1'0`` and
Part 3
^^^^^^
The third part of the :cmd:ref:`synth_ice40` flow is a series of commands for
mapping to DSPs. By default, the iCE40 flow will not map to the hardware DSP
blocks and will only be performed if called with the ``-dsp`` flag:
:yoscrypt:`synth_ice40 -dsp`. While our example has nothing that could be
mapped to DSPs we can still take a quick look at the commands here and describe
what they do.
The third part of the `synth_ice40` flow is a series of commands for mapping to
DSPs. By default, the iCE40 flow will not map to the hardware DSP blocks and
will only be performed if called with the ``-dsp`` flag: :yoscrypt:`synth_ice40
-dsp`. While our example has nothing that could be mapped to DSPs we can still
take a quick look at the commands here and describe what they do.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -482,29 +476,27 @@ what they do.
:name: synth_coarse3
:yoscrypt:`wreduce t:$mul` performs width reduction again, this time targetting
only cells of type ``$mul``. :yoscrypt:`techmap -map +/mul2dsp.v -map
+/ice40/dsp_map.v ... -D DSP_NAME=$__MUL16X16` uses :cmd:ref:`techmap` to map
``$mul`` cells to ``$__MUL16X16`` which are, in turn, mapped to the iCE40
``SB_MAC16``. Any multipliers which aren't compatible with conversion to
``$__MUL16X16`` are relabelled to ``$__soft_mul`` before :cmd:ref:`chtype`
changes them back to ``$mul``.
only cells of type `$mul`. :yoscrypt:`techmap -map +/mul2dsp.v -map
+/ice40/dsp_map.v ... -D DSP_NAME=$__MUL16X16` uses `techmap` to map `$mul`
cells to ``$__MUL16X16`` which are, in turn, mapped to the iCE40 ``SB_MAC16``.
Any multipliers which aren't compatible with conversion to ``$__MUL16X16`` are
relabelled to ``$__soft_mul`` before `chtype` changes them back to `$mul`.
During the mul2dsp conversion, some of the intermediate signals are marked with
the attribute ``mul2dsp``. By calling :yoscrypt:`select a:mul2dsp` we restrict
the following commands to only operate on the cells and wires used for these
signals. :cmd:ref:`setattr` removes the now unnecessary ``mul2dsp`` attribute.
:cmd:ref:`opt_expr` we've already come across for const folding and simple
expression rewriting, the ``-fine`` option just enables more fine-grain
optimizations. Then we perform width reduction a final time and clear the
selection.
signals. `setattr` removes the now unnecessary ``mul2dsp`` attribute.
`opt_expr` we've already come across for const folding and simple expression
rewriting, the ``-fine`` option just enables more fine-grain optimizations.
Then we perform width reduction a final time and clear the selection.
.. todo:: ``ice40_dsp`` is pmgen
Finally we have :cmd:ref:`ice40_dsp`: similar to the :cmd:ref:`memory_dff`
command we saw in the previous section, this merges any surrounding registers
into the ``SB_MAC16`` cell. This includes not just the input/output registers,
but also pipeline registers and even a post-adder where applicable: turning a
multiply + add into a single multiply-accumulate.
Finally we have `ice40_dsp`: similar to the `memory_dff` command we saw in the
previous section, this merges any surrounding registers into the ``SB_MAC16``
cell. This includes not just the input/output registers, but also pipeline
registers and even a post-adder where applicable: turning a multiply + add into
a single multiply-accumulate.
.. seealso:: Advanced usage docs for
:doc:`/using_yosys/synthesis/techmap_synth`
@ -522,44 +514,43 @@ That brings us to the fourth and final part for the iCE40 synthesis flow:
:caption: ``coarse`` section (part 4)
:name: synth_coarse4
Where before each type of arithmetic operation had its own cell, e.g. ``$add``,
we now want to extract these into ``$alu`` and ``$macc`` cells which can help
identify opportunities for reusing logic. We do this by running
:cmd:ref:`alumacc`, which we can see produce the following changes in our
example design:
Where before each type of arithmetic operation had its own cell, e.g. `$add`, we
now want to extract these into `$alu` and `$macc` cells which can help identify
opportunities for reusing logic. We do this by running `alumacc`, which we can
see produce the following changes in our example design:
.. literalinclude:: /code_examples/fifo/fifo.out
:language: doscon
:start-at: yosys> alumacc
:end-before: yosys> select
:caption: output of :cmd:ref:`alumacc`
:caption: output of `alumacc`
.. figure:: /_images/code_examples/fifo/rdata_alumacc.*
:class: width-helper invert-helper
:name: rdata_alumacc
``rdata`` output after :cmd:ref:`alumacc`
``rdata`` output after `alumacc`
Once these cells have been inserted, the call to :cmd:ref:`opt` can combine
cells which are now identical but may have been missed due to e.g. the
difference between ``$add`` and ``$sub``.
Once these cells have been inserted, the call to `opt` can combine cells which
are now identical but may have been missed due to e.g. the difference between
`$add` and `$sub`.
The other new command in this part is :doc:`/cmd/memory`. :cmd:ref:`memory` is
another macro command which we examine in more detail in
The other new command in this part is :doc:`/cmd/memory`. `memory` is another
macro command which we examine in more detail in
:doc:`/using_yosys/synthesis/memory`. For this document, let us focus just on
the step most relevant to our example: :cmd:ref:`memory_collect`. Up until this
point, our memory reads and our memory writes have been totally disjoint cells;
operating on the same memory only in the abstract. :cmd:ref:`memory_collect`
combines all of the reads and writes for a memory block into a single cell.
the step most relevant to our example: `memory_collect`. Up until this point,
our memory reads and our memory writes have been totally disjoint cells;
operating on the same memory only in the abstract. `memory_collect` combines all
of the reads and writes for a memory block into a single cell.
.. figure:: /_images/code_examples/fifo/rdata_coarse.*
:class: width-helper invert-helper
:name: rdata_coarse
``rdata`` output after :cmd:ref:`memory_collect`
``rdata`` output after `memory_collect`
Looking at the schematic after running :cmd:ref:`memory_collect` we see that our
``$memrd_v2`` cell has been replaced with a ``$mem_v2`` cell named ``data``, the
Looking at the schematic after running `memory_collect` we see that our
`$memrd_v2` cell has been replaced with a `$mem_v2` cell named ``data``, the
same name that we used in :ref:`fifo-v`. Where before we had a single set of
signals for address and enable, we now have one set for reading (``RD_*``) and
one for writing (``WR_*``), as well as both ``WR_DATA`` input and ``RD_DATA``
@ -592,8 +583,8 @@ If you skipped calling :yoscrypt:`read_verilog -D ICE40_HX -lib -specify
Memory blocks
^^^^^^^^^^^^^
Mapping to hard memory blocks uses a combination of :cmd:ref:`memory_libmap` and
:cmd:ref:`techmap`.
Mapping to hard memory blocks uses a combination of `memory_libmap` and
`techmap`.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -609,28 +600,28 @@ Mapping to hard memory blocks uses a combination of :cmd:ref:`memory_libmap` and
``rdata`` output after :ref:`map_ram`
The :ref:`map_ram` converts the generic ``$mem_v2`` into the iCE40
``SB_RAM40_4K`` (highlighted). We can also see the memory address has been
remapped, and the data bits have been reordered (or swizzled). There is also
now a ``$mux`` cell controlling the value of ``rdata``. In :ref:`fifo-v` we
wrote our memory as read-before-write, however the ``SB_RAM40_4K`` has undefined
behaviour when reading from and writing to the same address in the same cycle.
As a result, extra logic is added so that the generated circuit matches the
behaviour of the verilog. :ref:`no_rw_check` describes how we could change our
verilog to match our hardware instead.
The :ref:`map_ram` converts the generic `$mem_v2` into the iCE40 ``SB_RAM40_4K``
(highlighted). We can also see the memory address has been remapped, and the
data bits have been reordered (or swizzled). There is also now a `$mux` cell
controlling the value of ``rdata``. In :ref:`fifo-v` we wrote our memory as
read-before-write, however the ``SB_RAM40_4K`` has undefined behaviour when
reading from and writing to the same address in the same cycle. As a result,
extra logic is added so that the generated circuit matches the behaviour of the
verilog. :ref:`no_rw_check` describes how we could change our verilog to match
our hardware instead.
If we run :cmd:ref:`memory_libmap` under the :cmd:ref:`debug` command we can see
candidates which were identified for mapping, along with the costs of each and
what logic requires emulation.
If we run `memory_libmap` under the `debug` command we can see candidates which
were identified for mapping, along with the costs of each and what logic
requires emulation.
.. literalinclude:: /code_examples/fifo/fifo.libmap
:language: doscon
:lines: 2, 6-
The ``$__ICE40_RAM4K_`` cell is defined in the file |techlibs/ice40/brams.txt|_,
with the mapping to ``SB_RAM40_4K`` done by :cmd:ref:`techmap` using
with the mapping to ``SB_RAM40_4K`` done by `techmap` using
|techlibs/ice40/brams_map.v|_. Any leftover memory cells are then converted
into flip flops (the ``logic fallback``) with :cmd:ref:`memory_map`.
into flip flops (the ``logic fallback``) with `memory_map`.
.. |techlibs/ice40/brams.txt| replace:: :file:`techlibs/ice40/brams.txt`
.. _techlibs/ice40/brams.txt: https://github.com/YosysHQ/yosys/tree/main/techlibs/ice40/brams.txt
@ -654,8 +645,8 @@ into flip flops (the ``logic fallback``) with :cmd:ref:`memory_map`.
.. note::
The visual clutter on the ``RDATA`` output port (highlighted) is an
unfortunate side effect of :cmd:ref:`opt_clean` on the swizzled data bits. In
connecting the ``$mux`` input port directly to ``RDATA`` to reduce the number
unfortunate side effect of `opt_clean` on the swizzled data bits. In
connecting the `$mux` input port directly to ``RDATA`` to reduce the number
of wires, the ``$techmap579\data.0.0.RDATA`` wire becomes more visually
complex.
@ -667,11 +658,10 @@ into flip flops (the ``logic fallback``) with :cmd:ref:`memory_map`.
Arithmetic
^^^^^^^^^^
Uses :cmd:ref:`techmap` to map basic arithmetic logic to hardware. This sees
somewhat of an explosion in cells as multi-bit ``$mux`` and ``$adffe`` are
replaced with single-bit ``$_MUX_`` and ``$_DFFE_PP0P_`` cells, while the
``$alu`` is replaced with primitive ``$_OR_`` and ``$_NOT_`` gates and a
``$lut`` cell.
Uses `techmap` to map basic arithmetic logic to hardware. This sees somewhat of
an explosion in cells as multi-bit `$mux` and `$adffe` are replaced with
single-bit `$_MUX_` and `$_DFFE_PP0P_` cells, while the `$alu` is replaced with
primitive `$_OR_` and `$_NOT_` gates and a `$lut` cell.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -693,14 +683,14 @@ replaced with single-bit ``$_MUX_`` and ``$_DFFE_PP0P_`` cells, while the
Flip-flops
^^^^^^^^^^
Convert FFs to the types supported in hardware with :cmd:ref:`dfflegalize`, and
then use :cmd:ref:`techmap` to map them. In our example, this converts the
``$_DFFE_PP0P_`` cells to ``SB_DFFER``.
Convert FFs to the types supported in hardware with `dfflegalize`, and then use
`techmap` to map them. In our example, this converts the `$_DFFE_PP0P_` cells
to ``SB_DFFER``.
We also run :cmd:ref:`simplemap` here to convert any remaining cells which could
not be mapped to hardware into gate-level primitives. This includes optimizing
``$_MUX_`` cells where one of the inputs is a constant ``1'0``, replacing it
instead with an ``$_AND_`` cell.
We also run `simplemap` here to convert any remaining cells which could not be
mapped to hardware into gate-level primitives. This includes optimizing
`$_MUX_` cells where one of the inputs is a constant ``1'0``, replacing it
instead with an `$_AND_` cell.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -722,11 +712,10 @@ instead with an ``$_AND_`` cell.
LUTs
^^^^
:cmd:ref:`abc` and :cmd:ref:`techmap` are used to map LUTs; converting primitive
cell types to use ``$lut`` and ``SB_CARRY`` cells. Note that the iCE40 flow
uses :cmd:ref:`abc9` rather than :cmd:ref:`abc`. For more on what these do, and
what the difference between these two commands are, refer to
:doc:`/using_yosys/synthesis/abc`.
`abc` and `techmap` are used to map LUTs; converting primitive cell types to use
`$lut` and ``SB_CARRY`` cells. Note that the iCE40 flow uses `abc9` rather than
`abc`. For more on what these do, and what the difference between these two
commands are, refer to :doc:`/using_yosys/synthesis/abc`.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -742,8 +731,8 @@ what the difference between these two commands are, refer to
``rdata`` output after :ref:`map_luts`
Finally we use :cmd:ref:`techmap` to map the generic ``$lut`` cells to iCE40
``SB_LUT4`` cells.
Finally we use `techmap` to map the generic `$lut` cells to iCE40 ``SB_LUT4``
cells.
.. literalinclude:: /cmd/synth_ice40.rst
:language: yoscrypt
@ -769,12 +758,12 @@ Other cells
The following commands may also be used for mapping other cells:
:cmd:ref:`hilomap`
`hilomap`
Some architectures require special driver cells for driving a constant hi or
lo value. This command replaces simple constants with instances of such
driver cells.
:cmd:ref:`iopadmap`
`iopadmap`
Top-level input/outputs must usually be implemented using special I/O-pad
cells. This command inserts such cells to the design.
@ -801,28 +790,27 @@ The new commands here are:
- :doc:`/cmd/stat`, and
- :doc:`/cmd/blackbox`.
The output from :cmd:ref:`stat` is useful for checking resource utilization;
providing a list of cells used in the design and the number of each, as well as
the number of other resources used such as wires and processes. For this
design, the final call to :cmd:ref:`stat` should look something like the
following:
The output from `stat` is useful for checking resource utilization; providing a
list of cells used in the design and the number of each, as well as the number
of other resources used such as wires and processes. For this design, the final
call to `stat` should look something like the following:
.. literalinclude:: /code_examples/fifo/fifo.stat
:language: doscon
:start-at: yosys> stat -top fifo
Note that the :yoscrypt:`-top fifo` here is optional. :cmd:ref:`stat` will
automatically use the module with the ``top`` attribute set, which ``fifo`` was
when we called :cmd:ref:`hierarchy`. If no module is marked ``top``, then stats
will be shown for each module selected.
Note that the :yoscrypt:`-top fifo` here is optional. `stat` will automatically
use the module with the ``top`` attribute set, which ``fifo`` was when we called
`hierarchy`. If no module is marked ``top``, then stats will be shown for each
module selected.
The :cmd:ref:`stat` output is also useful as a kind of sanity-check: Since we
have already run :cmd:ref:`proc`, we wouldn't expect there to be any processes.
We also expect ``data`` to use hard memory; if instead of an ``SB_RAM40_4K`` saw
a high number of flip-flops being used we might suspect something was wrong.
The `stat` output is also useful as a kind of sanity-check: Since we have
already run `proc`, we wouldn't expect there to be any processes. We also expect
``data`` to use hard memory; if instead of an ``SB_RAM40_4K`` saw a high number
of flip-flops being used we might suspect something was wrong.
If we instead called :cmd:ref:`stat` immediately after :yoscrypt:`read_verilog
fifo.v` we would see something very different:
If we instead called `stat` immediately after :yoscrypt:`read_verilog fifo.v` we
would see something very different:
.. literalinclude:: /code_examples/fifo/fifo.stat
:language: doscon
@ -845,10 +833,10 @@ The iCE40 synthesis flow has the following output modes available:
As an example, if we called :yoscrypt:`synth_ice40 -top fifo -json fifo.json`,
our synthesized ``fifo`` design will be output as :file:`fifo.json`. We can
then read the design back into Yosys with :cmd:ref:`read_json`, but make sure
you use :yoscrypt:`design -reset` or open a new interactive terminal first. The
JSON output we get can also be loaded into `nextpnr`_ to do place and route; but
that is beyond the scope of this documentation.
then read the design back into Yosys with `read_json`, but make sure you use
:yoscrypt:`design -reset` or open a new interactive terminal first. The JSON
output we get can also be loaded into `nextpnr`_ to do place and route; but that
is beyond the scope of this documentation.
.. _nextpnr: https://github.com/YosysHQ/nextpnr

11
docs/source/getting_started/installation.rst
View file

@ -88,7 +88,7 @@ A C++ compiler with C++17 support is required as well as some standard tools
such as GNU Flex, GNU Bison, Make and Python. Some additional tools: readline,
libffi, Tcl and zlib; are optional but enabled by default (see
:makevar:`ENABLE_*` settings in Makefile). Graphviz and Xdot are used by the
:cmd:ref:`show` command to display schematics.
`show` command to display schematics.
Installing all prerequisites for Ubuntu 20.04:
@ -109,7 +109,7 @@ Installing all prerequisites for macOS 11 (with Homebrew):
Running the build system
^^^^^^^^^^^^^^^^^^^^^^^^
From the root `yosys` directory, call the following commands:
From the root ``yosys`` directory, call the following commands:
.. code:: console
@ -117,7 +117,7 @@ From the root `yosys` directory, call the following commands:
sudo make install
This will build and then install Yosys, making it available on the command line
as `yosys`. Note that this also downloads, builds, and installs `ABC`_ (using
as ``yosys``. Note that this also downloads, builds, and installs `ABC`_ (using
:program:`yosys-abc` as the executable name).
.. _ABC: https://github.com/berkeley-abc/abc
@ -184,9 +184,8 @@ directories:
``passes/``
This directory contains a subdirectory for each pass or group of passes. For
example as of this writing the directory :file:`passes/hierarchy/` contains the
code for three passes: :cmd:ref:`hierarchy`, :cmd:ref:`submod`, and
:cmd:ref:`uniquify`.
example as of this writing the directory :file:`passes/hierarchy/` contains
the code for three passes: `hierarchy`, `submod`, and `uniquify`.
``techlibs/``
This directory contains simulation models and standard implementations for

82
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@ -7,8 +7,7 @@ file format and how you can make your own synthesis scripts.
Yosys script files typically use the :file:`.ys` extension and contain a set of
commands for Yosys to run sequentially. These commands are the same ones we
were using on the previous page like :cmd:ref:`read_verilog` and
:cmd:ref:`hierarchy`.
were using on the previous page like `read_verilog` and `hierarchy`.
Script parsing
~~~~~~~~~~~~~~
@ -39,9 +38,9 @@ Another special character that can be used in Yosys scripts is the bang ``!``.
Anything after the bang will be executed as a shell command. This can only be
terminated with a new line. Any semicolons, hashes, or other special characters
will be passed to the shell. If an error code is returned from the shell it
will be raised by Yosys. :cmd:ref:`exec` provides a much more flexible way of
executing commands, allowing the output to be logged and more control over when
to generate errors.
will be raised by Yosys. `exec` provides a much more flexible way of executing
commands, allowing the output to be logged and more control over when to
generate errors.
The synthesis starter script
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -62,24 +61,23 @@ already, let's take a look at some of those script files now.
:caption: A section of :file:`fifo.ys`, generating the images used for :ref:`addr_gen_example`
:name: fifo-ys
The first command there, :yoscrypt:`echo on`, uses :cmd:ref:`echo` to enable
command echoes on. This is how we generated the code listing for
The first command there, :yoscrypt:`echo on`, uses `echo` to enable command
echoes on. This is how we generated the code listing for
:ref:`hierarchy_output`. Turning command echoes on prints the ``yosys>
hierarchy -top addr_gen`` line, making the output look the same as if it were an
interactive terminal. :yoscrypt:`hierarchy -top addr_gen` is of course the
command we were demonstrating, including the output text and an image of the
design schematic after running it.
We briefly touched on :cmd:ref:`select` when it came up in
:cmd:ref:`synth_ice40`, but let's look at it more now.
We briefly touched on `select` when it came up in `synth_ice40`, but let's look
at it more now.
.. _select_intro:
Selections intro
^^^^^^^^^^^^^^^^
The :cmd:ref:`select` command is used to modify and view the list of selected
objects:
The `select` command is used to modify and view the list of selected objects:
.. literalinclude:: /code_examples/fifo/fifo.out
:language: doscon
@ -99,7 +97,7 @@ signifies we are matching on the *cell type*, and the ``*`` means to match
anything. For this (very simple) selection, we are trying to find all of the
cells, regardless of their type. The active selection is now shown as
``[addr_gen]*``, indicating some sub-selection of the ``addr_gen`` module. This
gives us the ``$add`` and ``$eq`` cells, which we want to highlight for the
gives us the `$add` and `$eq` cells, which we want to highlight for the
:ref:`addr_gen_hier` image.
.. _select_new_cells:
@ -111,15 +109,16 @@ by referring to it as ``@new_cells``, which we will see later. Then we clear
the selection so that the following commands can operate on the full design.
While we split that out for this document, we could have done the same thing in
a single line by calling :yoscrypt:`select -set new_cells addr_gen/t:*`. If we
know we only have the one module in our design, we can even skip the `addr_gen/`
part. Looking further down :ref:`the fifo.ys code <fifo-ys>` we can see this
with :yoscrypt:`select -set new_cells t:$mux t:*dff`. We can also see in that
command that selections don't have to be limited to a single statement.
know we only have the one module in our design, we can even skip the
``addr_gen/`` part. Looking further down :ref:`the fifo.ys code <fifo-ys>` we
can see this with :yoscrypt:`select -set new_cells t:$mux t:*dff`. We can also
see in that command that selections don't have to be limited to a single
statement.
Many commands also support an optional ``[selection]`` argument which can be
used to override the currently selected objects. We could, for example, call
:yoscrypt:`clean addr_gen` to have :cmd:ref:`clean` operate on *just* the
``addr_gen`` module.
:yoscrypt:`clean addr_gen` to have `clean` operate on *just* the ``addr_gen``
module.
Detailed documentation of the select framework can be found under
:doc:`/using_yosys/more_scripting/selections` or in the command reference at
@ -130,23 +129,23 @@ Detailed documentation of the select framework can be found under
Displaying schematics
^^^^^^^^^^^^^^^^^^^^^
While the :cmd:ref:`select` command is very useful, sometimes nothing beats
being able to see a design for yourself. This is where :cmd:ref:`show` comes
in. Note that this document is just an introduction to the :cmd:ref:`show`
command, only covering the basics. For more information, including a guide on
what the different symbols represent, see :ref:`interactive_show` and the
While the `select` command is very useful, sometimes nothing beats being able to
see a design for yourself. This is where `show` comes in. Note that this
document is just an introduction to the `show` command, only covering the
basics. For more information, including a guide on what the different symbols
represent, see :ref:`interactive_show` and the
:doc:`/using_yosys/more_scripting/interactive_investigation` page.
.. figure:: /_images/code_examples/fifo/addr_gen_show.*
:class: width-helper invert-helper
:name: addr_gen_show
Calling :yoscrypt:`show addr_gen` after :cmd:ref:`hierarchy`
Calling :yoscrypt:`show addr_gen` after `hierarchy`
.. note::
The :cmd:ref:`show` command requires a working installation of `GraphViz`_
and `xdot`_ for displaying the actual circuit diagrams.
The `show` command requires a working installation of `GraphViz`_ and `xdot`_
for displaying the actual circuit diagrams.
.. _GraphViz: http://www.graphviz.org/
.. _xdot: https://github.com/jrfonseca/xdot.py
@ -160,8 +159,8 @@ we see the following:
:start-at: -prefix addr_gen_show
:end-before: yosys> show
Calling :cmd:ref:`show` with :yoscrypt:`-format dot` tells it we want to output
a :file:`.dot` file rather than opening it for display. The :yoscrypt:`-prefix
Calling `show` with :yoscrypt:`-format dot` tells it we want to output a
:file:`.dot` file rather than opening it for display. The :yoscrypt:`-prefix
addr_gen_show` option indicates we want the file to be called
:file:`addr_gen_show.{*}`. Remember, we do this in :file:`fifo.ys` because we
need to store the image for displaying in the documentation you're reading. But
@ -184,8 +183,8 @@ like when we called :yoscrypt:`select -module addr_gen` in :ref:`select_intro`.
That last parameter doesn't have to be a module name, it can be any valid
selection string. Remember when we :ref:`assigned a name to a
selection<select_new_cells>` and called it ``new_cells``? We saw in the
:yoscrypt:`select -list` output that it contained two cells, an ``$add`` and an
``$eq``. We can call :cmd:ref:`show` on that selection just as easily:
:yoscrypt:`select -list` output that it contained two cells, an `$add` and an
`$eq`. We can call `show` on that selection just as easily:
.. figure:: /_images/code_examples/fifo/new_cells_show.*
:class: width-helper invert-helper
@ -207,21 +206,20 @@ the two ``PROC`` blocks. To achieve this highlight, we make use of the
Calling :yoscrypt:`show -color maroon3 @new_cells -color cornflowerblue p:* -notitle`
As described in the the :cmd:ref:`help` output for :cmd:ref:`show` (or by
clicking on the :cmd:ref:`show` link), colors are specified as :yoscrypt:`-color
<color> <object>`. Color names for the ``<color>`` portion can be found on the
`GraphViz color docs`_. Unlike the final :cmd:ref:`show` parameter which can
have be any selection string, the ``<object>`` part must be a single selection
expression or named selection. That means while we can use ``@new_cells``, we
couldn't use ``t:$eq t:$add``. In general, if a command lists ``[selection]``
as its final parameter it can be any selection string. Any selections that are
not the final parameter, such as those used in options, must be a single
expression instead.
As described in the the `help` output for `show` (or by clicking on the `show`
link), colors are specified as :yoscrypt:`-color <color> <object>`. Color names
for the ``<color>`` portion can be found on the `GraphViz color docs`_. Unlike
the final `show` parameter which can have be any selection string, the
``<object>`` part must be a single selection expression or named selection.
That means while we can use ``@new_cells``, we couldn't use ``t:$eq t:$add``.
In general, if a command lists ``[selection]`` as its final parameter it can be
any selection string. Any selections that are not the final parameter, such as
those used in options, must be a single expression instead.
.. _GraphViz color docs: https://graphviz.org/doc/info/colors
For all of the options available to :cmd:ref:`show`, check the command reference
at :doc:`/cmd/show`.
For all of the options available to `show`, check the command reference at
:doc:`/cmd/show`.
.. seealso:: :ref:`interactive_show` on the
:doc:`/using_yosys/more_scripting/interactive_investigation` page.

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@ -27,18 +27,28 @@ available, go to :ref:`commandindex`.
.. todolist::
.. only:: html
Table of contents
-----------------
.. toctree::
:maxdepth: 3
:includehidden:
Yosys (index) <self>
introduction
getting_started/index
using_yosys/index
yosys_internals/index
appendix
.. toctree::
:caption: Appendix
:titlesonly:
:includehidden:
appendix/primer
appendix/rtlil_text
appendix/auxlibs
appendix/auxprogs
bib
cell_index
cmd_ref

26
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@ -161,9 +161,9 @@ Benefits of open source HDL synthesis
- Cost (also applies to ``free as in free beer`` solutions):
Today the cost for a mask set in 180nm technology is far less than
the cost for the design tools needed to design the mask layouts. Open Source
ASIC flows are an important enabler for ASIC-level Open Source Hardware.
Today the cost for a mask set in 180nm technology is far less than the cost
for the design tools needed to design the mask layouts. Open Source ASIC flows
are an important enabler for ASIC-level Open Source Hardware.
- Availability and Reproducibility:
@ -171,21 +171,23 @@ Benefits of open source HDL synthesis
else can also use. Even if most universities have access to all major
commercial tools, you usually do not have easy access to the version that was
used in a research project a couple of years ago. With Open Source tools you
can even release the source code of the tool you have used alongside your data.
can even release the source code of the tool you have used alongside your
data.
- Framework:
Yosys is not only a tool. It is a framework that can be used as basis for other
developments, so researchers and hackers alike do not need to re-invent the
basic functionality. Extensibility was one of Yosys' design goals.
Yosys is not only a tool. It is a framework that can be used as basis for
other developments, so researchers and hackers alike do not need to re-invent
the basic functionality. Extensibility was one of Yosys' design goals.
- All-in-one:
Because of the framework characteristics of Yosys, an increasing number of features
become available in one tool. Yosys not only can be used for circuit synthesis but
also for formal equivalence checking, SAT solving, and for circuit analysis, to
name just a few other application domains. With proprietary software one needs to
learn a new tool for each of these applications.
Because of the framework characteristics of Yosys, an increasing number of
features become available in one tool. Yosys not only can be used for circuit
synthesis but also for formal equivalence checking, SAT solving, and for
circuit analysis, to name just a few other application domains. With
proprietary software one needs to learn a new tool for each of these
applications.
- Educational Tool:

2
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View file

@ -1,3 +1,3 @@
furo
furo-ys @ git+https://github.com/YosysHQ/furo-ys
sphinxcontrib-bibtex
rtds-action

249
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@ -13,9 +13,9 @@ A look at the show command
.. TODO:: merge into :doc:`/getting_started/scripting_intro` show section
This section explores the :cmd:ref:`show` command and explains the symbols used
in the circuit diagrams generated by it. The code used is included in the Yosys
code base under |code_examples/show|_.
This section explores the `show` command and explains the symbols used in the
circuit diagrams generated by it. The code used is included in the Yosys code
base under |code_examples/show|_.
.. |code_examples/show| replace:: :file:`docs/source/code_examples/show`
.. _code_examples/show: https://github.com/YosysHQ/yosys/tree/main/docs/source/code_examples/show
@ -24,7 +24,7 @@ A simple circuit
^^^^^^^^^^^^^^^^
:ref:`example_v` below provides the Verilog code for a simple circuit which we
will use to demonstrate the usage of :cmd:ref:`show` in a simple setting.
will use to demonstrate the usage of `show` in a simple setting.
.. literalinclude:: /code_examples/show/example.v
:language: Verilog
@ -32,11 +32,10 @@ will use to demonstrate the usage of :cmd:ref:`show` in a simple setting.
:name: example_v
The Yosys synthesis script we will be running is included as
:numref:`example_ys`. Note that :cmd:ref:`show` is called with the ``-pause``
option, that halts execution of the Yosys script until the user presses the
Enter key. Using :yoscrypt:`show -pause` also allows the user to enter an
interactive shell to further investigate the circuit before continuing
synthesis.
:numref:`example_ys`. Note that `show` is called with the ``-pause`` option,
that halts execution of the Yosys script until the user presses the Enter key.
Using :yoscrypt:`show -pause` also allows the user to enter an interactive shell
to further investigate the circuit before continuing synthesis.
.. literalinclude:: /code_examples/show/example_show.ys
:language: yoscrypt
@ -58,7 +57,7 @@ is shown.
.. figure:: /_images/code_examples/show/example_first.*
:class: width-helper invert-helper
Output of the first :cmd:ref:`show` command in :numref:`example_ys`
Output of the first `show` command in :numref:`example_ys`
The first output shows the design directly after being read by the Verilog
front-end. Input and output ports are displayed as octagonal shapes. Cells are
@ -66,7 +65,7 @@ displayed as rectangles with inputs on the left and outputs on the right side.
The cell labels are two lines long: The first line contains a unique identifier
for the cell and the second line contains the cell type. Internal cell types are
prefixed with a dollar sign. For more details on the internal cell library, see
:doc:`/yosys_internals/formats/cell_library`.
:doc:`/cell_index`.
Constants are shown as ellipses with the constant value as label. The syntax
``<bit_width>'<bits>`` is used for constants that are not 32-bit wide and/or
@ -81,43 +80,43 @@ internal representation of the decision-trees and synchronization events
modelled in a Verilog ``always``-block. The label reads ``PROC`` followed by a
unique identifier in the first line and contains the source code location of the
original ``always``-block in the second line. Note how the multiplexer from the
``?:``-expression is represented as a ``$mux`` cell but the multiplexer from the
``?:``-expression is represented as a `$mux` cell but the multiplexer from the
``if``-statement is yet still hidden within the process.
The :cmd:ref:`proc` command transforms the process from the first diagram into a
The `proc` command transforms the process from the first diagram into a
multiplexer and a d-type flip-flop, which brings us to the second diagram:
.. figure:: /_images/code_examples/show/example_second.*
:class: width-helper invert-helper
Output of the second :cmd:ref:`show` command in :numref:`example_ys`
Output of the second `show` command in :numref:`example_ys`
The Rhombus shape to the right is a dangling wire. (Wire nodes are only shown if
they are dangling or have "public" names, for example names assigned from the
Verilog input.) Also note that the design now contains two instances of a
``BUF``-node. These are artefacts left behind by the :cmd:ref:`proc` command. It
is quite usual to see such artefacts after calling commands that perform changes
in the design, as most commands only care about doing the transformation in the
least complicated way, not about cleaning up after them. The next call to
:cmd:ref:`clean` (or :cmd:ref:`opt`, which includes :cmd:ref:`clean` as one of
its operations) will clean up these artefacts. This operation is so common in
Yosys scripts that it can simply be abbreviated with the ``;;`` token, which
doubles as separator for commands. Unless one wants to specifically analyze this
artefacts left behind some operations, it is therefore recommended to always
call :cmd:ref:`clean` before calling :cmd:ref:`show`.
``BUF``-node. These are artefacts left behind by the `proc` command. It is quite
usual to see such artefacts after calling commands that perform changes in the
design, as most commands only care about doing the transformation in the least
complicated way, not about cleaning up after them. The next call to `clean` (or
`opt`, which includes `clean` as one of its operations) will clean up these
artefacts. This operation is so common in Yosys scripts that it can simply be
abbreviated with the ``;;`` token, which doubles as separator for commands.
Unless one wants to specifically analyze this artefacts left behind some
operations, it is therefore recommended to always call `clean` before calling
`show`.
In this script we directly call :cmd:ref:`opt` as the next step, which finally
leads us to the third diagram:
In this script we directly call `opt` as the next step, which finally leads us
to the third diagram:
.. figure:: /_images/code_examples/show/example_third.*
:class: width-helper invert-helper
:name: example_out
Output of the third :cmd:ref:`show` command in :ref:`example_ys`
Output of the third `show` command in :ref:`example_ys`
Here we see that the :cmd:ref:`opt` command not only has removed the artifacts
left behind by :cmd:ref:`proc`, but also determined correctly that it can remove
the first ``$mux`` cell without changing the behavior of the circuit.
Here we see that the `opt` command not only has removed the artifacts left
behind by `proc`, but also determined correctly that it can remove the first
`$mux` cell without changing the behavior of the circuit.
Break-out boxes for signal vectors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -129,7 +128,7 @@ accesses.
:caption: :file:`splice.v`
:name: splice_src
Notice how the output for this circuit from the :cmd:ref:`show` command
Notice how the output for this circuit from the `show` command
(:numref:`splice_dia`) appears quite complex. This is an unfortunate side effect
of the way Yosys handles signal vectors (aka. multi-bit wires or buses) as
native objects. While this provides great advantages when analyzing circuits
@ -169,7 +168,7 @@ mapped to a cell library:
:name: first_pitfall
A half-adder built from simple CMOS gates, demonstrating common pitfalls when
using :cmd:ref:`show`
using `show`
.. literalinclude:: /code_examples/show/cmos.ys
:language: yoscrypt
@ -188,8 +187,8 @@ individual bits, resulting in an unnecessary complex diagram.
:class: width-helper invert-helper
:name: second_pitfall
Effects of :cmd:ref:`splitnets` command and of providing a cell library on
design in :numref:`first_pitfall`
Effects of `splitnets` command and of providing a cell library on design in
:numref:`first_pitfall`
.. literalinclude:: /code_examples/show/cmos.ys
:language: yoscrypt
@ -201,11 +200,11 @@ individual bits, resulting in an unnecessary complex diagram.
For :numref:`second_pitfall`, Yosys has been given a description of the cell
library as Verilog file containing blackbox modules. There are two ways to load
cell descriptions into Yosys: First the Verilog file for the cell library can be
passed directly to the :cmd:ref:`show` command using the ``-lib <filename>``
option. Secondly it is possible to load cell libraries into the design with the
passed directly to the `show` command using the ``-lib <filename>`` option.
Secondly it is possible to load cell libraries into the design with the
:yoscrypt:`read_verilog -lib <filename>` command. The second method has the
great advantage that the library only needs to be loaded once and can then be
used in all subsequent calls to the :cmd:ref:`show` command.
used in all subsequent calls to the `show` command.
In addition to that, :numref:`second_pitfall` was generated after
:yoscrypt:`splitnet -ports` was run on the design. This command splits all
@ -216,22 +215,22 @@ module ports. Per default the command only operates on interior signals.
Miscellaneous notes
^^^^^^^^^^^^^^^^^^^
Per default the :cmd:ref:`show` command outputs a temporary dot file and
launches ``xdot`` to display it. The options ``-format``, ``-viewer`` and
``-prefix`` can be used to change format, viewer and filename prefix. Note that
the ``pdf`` and ``ps`` format are the only formats that support plotting
multiple modules in one run. The ``dot`` format can be used to output multiple
modules, however ``xdot`` will raise an error when trying to read them.
Per default the `show` command outputs a temporary dot file and launches
``xdot`` to display it. The options ``-format``, ``-viewer`` and ``-prefix`` can
be used to change format, viewer and filename prefix. Note that the ``pdf`` and
``ps`` format are the only formats that support plotting multiple modules in one
run. The ``dot`` format can be used to output multiple modules, however
``xdot`` will raise an error when trying to read them.
In densely connected circuits it is sometimes hard to keep track of the
individual signal wires. For these cases it can be useful to call
:cmd:ref:`show` with the ``-colors <integer>`` argument, which randomly assigns
colors to the nets. The integer (> 0) is used as seed value for the random color
assignments. Sometimes it is necessary it try some values to find an assignment
of colors that looks good.
individual signal wires. For these cases it can be useful to call `show` with
the ``-colors <integer>`` argument, which randomly assigns colors to the nets.
The integer (> 0) is used as seed value for the random color assignments.
Sometimes it is necessary it try some values to find an assignment of colors
that looks good.
The command :yoscrypt:`help show` prints a complete listing of all options
supported by the :cmd:ref:`show` command.
supported by the `show` command.
Navigating the design
~~~~~~~~~~~~~~~~~~~~~
@ -244,10 +243,10 @@ relevant portions of the circuit.
In addition to *what* to display one also needs to carefully decide *when* to
display it, with respect to the synthesis flow. In general it is a good idea to
troubleshoot a circuit in the earliest state in which a problem can be
reproduced. So if, for example, the internal state before calling the
:cmd:ref:`techmap` command already fails to verify, it is better to troubleshoot
the coarse-grain version of the circuit before :cmd:ref:`techmap` than the
gate-level circuit after :cmd:ref:`techmap`.
reproduced. So if, for example, the internal state before calling the `techmap`
command already fails to verify, it is better to troubleshoot the coarse-grain
version of the circuit before `techmap` than the gate-level circuit after
`techmap`.
.. Note::
@ -260,31 +259,29 @@ Interactive navigation
^^^^^^^^^^^^^^^^^^^^^^
Once the right state within the synthesis flow for debugging the circuit has
been identified, it is recommended to simply add the :cmd:ref:`shell` command to
the matching place in the synthesis script. This command will stop the synthesis
at the specified moment and go to shell mode, where the user can interactively
been identified, it is recommended to simply add the `shell` command to the
matching place in the synthesis script. This command will stop the synthesis at
the specified moment and go to shell mode, where the user can interactively
enter commands.
For most cases, the shell will start with the whole design selected (i.e. when
the synthesis script does not already narrow the selection). The command
:cmd:ref:`ls` can now be used to create a list of all modules. The command
:cmd:ref:`cd` can be used to switch to one of the modules (type ``cd ..`` to
switch back). Now the :cmd:ref:`ls` command lists the objects within that
module. This is demonstrated below using :file:`example.v` from `A simple
circuit`_:
the synthesis script does not already narrow the selection). The command `ls`
can now be used to create a list of all modules. The command `cd` can be used to
switch to one of the modules (type ``cd ..`` to switch back). Now the `ls`
command lists the objects within that module. This is demonstrated below using
:file:`example.v` from `A simple circuit`_:
.. literalinclude:: /code_examples/show/example.out
:language: doscon
:start-at: yosys> ls
:end-before: yosys [example]> dump
:caption: Output of :cmd:ref:`ls` and :cmd:ref:`cd` after running :file:`yosys example.v`
:caption: Output of `ls` and `cd` after running :file:`yosys example.v`
:name: lscd
When a module is selected using the :cmd:ref:`cd` command, all commands (with a
few exceptions, such as the ``read_`` and ``write_`` commands) operate only on
the selected module. This can also be useful for synthesis scripts where
different synthesis strategies should be applied to different modules in the
design.
When a module is selected using the `cd` command, all commands (with a few
exceptions, such as the ``read_`` and ``write_`` commands) operate only on the
selected module. This can also be useful for synthesis scripts where different
synthesis strategies should be applied to different modules in the design.
We can see that the cell names from :numref:`example_out` are just abbreviations
of the actual cell names, namely the part after the last dollar-sign. Most
@ -292,15 +289,14 @@ auto-generated names (the ones starting with a dollar sign) are rather long and
contains some additional information on the origin of the named object. But in
most cases those names can simply be abbreviated using the last part.
Usually all interactive work is done with one module selected using the
:cmd:ref:`cd` command. But it is also possible to work from the design-context
(``cd ..``). In this case all object names must be prefixed with
``<module_name>/``. For example ``a*/b*`` would refer to all objects whose names
start with ``b`` from all modules whose names start with ``a``.
Usually all interactive work is done with one module selected using the `cd`
command. But it is also possible to work from the design-context (``cd ..``). In
this case all object names must be prefixed with ``<module_name>/``. For example
``a*/b*`` would refer to all objects whose names start with ``b`` from all
modules whose names start with ``a``.
The :cmd:ref:`dump` command can be used to print all information about an
object. For example, calling :yoscrypt:`dump $2` after the :yoscrypt:`cd
example` above:
The `dump` command can be used to print all information about an object. For
example, calling :yoscrypt:`dump $2` after the :yoscrypt:`cd example` above:
.. literalinclude:: /code_examples/show/example.out
:language: RTLIL
@ -323,11 +319,10 @@ tools).
- The selection mechanism, especially patterns such as ``%ci`` and ``%co``, can
be used to figure out how parts of the design are connected.
- Commands such as :cmd:ref:`submod`, :cmd:ref:`expose`, and :cmd:ref:`splice`
can be used to transform the design into an equivalent design that is easier
to analyse.
- Commands such as :cmd:ref:`eval` and :cmd:ref:`sat` can be used to investigate
the behavior of the circuit.
- Commands such as `submod`, `expose`, and `splice` can be used to transform the
design into an equivalent design that is easier to analyse.
- Commands such as `eval` and `sat` can be used to investigate the behavior of
the circuit.
- :doc:`/cmd/show`.
- :doc:`/cmd/dump`.
- :doc:`/cmd/add` and :doc:`/cmd/delete` can be used to modify and reorganize a
@ -342,10 +337,10 @@ The code used is included in the Yosys code base under
Changing design hierarchy
^^^^^^^^^^^^^^^^^^^^^^^^^
Commands such as :cmd:ref:`flatten` and :cmd:ref:`submod` can be used to change
the design hierarchy, i.e. flatten the hierarchy or moving parts of a module to
a submodule. This has applications in synthesis scripts as well as in reverse
engineering and analysis. An example using :cmd:ref:`submod` is shown below for
Commands such as `flatten` and `submod` can be used to change the design
hierarchy, i.e. flatten the hierarchy or moving parts of a module to a
submodule. This has applications in synthesis scripts as well as in reverse
engineering and analysis. An example using `submod` is shown below for
reorganizing a module in Yosys and checking the resulting circuit.
.. literalinclude:: /code_examples/scrambler/scrambler.v
@ -388,10 +383,10 @@ Analyzing the resulting circuit with :doc:`/cmd/eval`:
Behavioral changes
^^^^^^^^^^^^^^^^^^
Commands such as :cmd:ref:`techmap` can be used to make behavioral changes to
the design, for example changing asynchronous resets to synchronous resets. This
has applications in design space exploration (evaluation of various
architectures for one circuit).
Commands such as `techmap` can be used to make behavioral changes to the design,
for example changing asynchronous resets to synchronous resets. This has
applications in design space exploration (evaluation of various architectures
for one circuit).
The following techmap map file replaces all positive-edge async reset flip-flops
with positive-edge sync reset flip-flops. The code is taken from the example
@ -425,7 +420,7 @@ Yosys script for ASIC synthesis of the Amber ARMv2 CPU.
endmodule
For more on the :cmd:ref:`techmap` command, see the page on
For more on the `techmap` command, see the page on
:doc:`/yosys_internals/techmap`.
Advanced investigation techniques
@ -448,12 +443,12 @@ Recall the ``memdemo`` design from :ref:`advanced_logic_cones`:
Because this produces a rather large circuit, it can be useful to split it into
smaller parts for viewing and working with. :numref:`submod` does exactly that,
utilising the :cmd:ref:`submod` command to split the circuit into three
sections: ``outstage``, ``selstage``, and ``scramble``.
utilising the `submod` command to split the circuit into three sections:
``outstage``, ``selstage``, and ``scramble``.
.. literalinclude:: /code_examples/selections/submod.ys
:language: yoscrypt
:caption: Using :cmd:ref:`submod` to break up the circuit from :file:`memdemo.v`
:caption: Using `submod` to break up the circuit from :file:`memdemo.v`
:start-after: cd memdemo
:end-before: cd ..
:name: submod
@ -481,9 +476,9 @@ below.
Evaluation of combinatorial circuits
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The :cmd:ref:`eval` command can be used to evaluate combinatorial circuits. As
an example, we will use the ``selstage`` subnet of ``memdemo`` which we found
above and is shown in :numref:`selstage`.
The `eval` command can be used to evaluate combinatorial circuits. As an
example, we will use the ``selstage`` subnet of ``memdemo`` which we found above
and is shown in :numref:`selstage`.
.. todo:: replace inline code
@ -526,21 +521,21 @@ The ``-table`` option can be used to create a truth table. For example:
Assumed undef (x) value for the following signals: \s2
Note that the :cmd:ref:`eval` command (as well as the :cmd:ref:`sat` command
discussed in the next sections) does only operate on flattened modules. It can
not analyze signals that are passed through design hierarchy levels. So the
:cmd:ref:`flatten` command must be used on modules that instantiate other
modules before these commands can be applied.
Note that the `eval` command (as well as the `sat` command discussed in the next
sections) does only operate on flattened modules. It can not analyze signals
that are passed through design hierarchy levels. So the `flatten` command must
be used on modules that instantiate other modules before these commands can be
applied.
Solving combinatorial SAT problems
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Often the opposite of the :cmd:ref:`eval` command is needed, i.e. the circuits
output is given and we want to find the matching input signals. For small
circuits with only a few input bits this can be accomplished by trying all
possible input combinations, as it is done by the ``eval -table`` command. For
larger circuits however, Yosys provides the :cmd:ref:`sat` command that uses a
`SAT`_ solver, `MiniSAT`_, to solve this kind of problems.
Often the opposite of the `eval` command is needed, i.e. the circuits output is
given and we want to find the matching input signals. For small circuits with
only a few input bits this can be accomplished by trying all possible input
combinations, as it is done by the ``eval -table`` command. For larger circuits
however, Yosys provides the `sat` command that uses a `SAT`_ solver, `MiniSAT`_,
to solve this kind of problems.
.. _SAT: http://en.wikipedia.org/wiki/Circuit_satisfiability
@ -551,9 +546,9 @@ larger circuits however, Yosys provides the :cmd:ref:`sat` command that uses a
While it is possible to perform model checking directly in Yosys, it
is highly recommended to use SBY or EQY for formal hardware verification.
The :cmd:ref:`sat` command works very similar to the :cmd:ref:`eval` command.
The main difference is that it is now also possible to set output values and
find the corresponding input values. For Example:
The `sat` command works very similar to the `eval` command. The main difference
is that it is now also possible to set output values and find the corresponding
input values. For Example:
.. todo:: replace inline code
@ -580,8 +575,8 @@ find the corresponding input values. For Example:
\s1 0 0 00
\s2 0 0 00
Note that the :cmd:ref:`sat` command supports signal names in both arguments to
the ``-set`` option. In the above example we used ``-set s1 s2`` to constraint
Note that the `sat` command supports signal names in both arguments to the
``-set`` option. In the above example we used ``-set s1 s2`` to constraint
``s1`` and ``s2`` to be equal. When more complex constraints are needed, a
wrapper circuit must be constructed that checks the constraints and signals if
the constraint was met using an extra output port, which then can be forced to a
@ -642,8 +637,8 @@ of course be to perform the test in 32 bits, for example by replacing ``p !=
a*b`` in the miter with ``p != {16'd0,a}b``, or by using a temporary variable
for the 32 bit product ``a*b``. But as 31 fits well into 8 bits (and as the
purpose of this document is to show off Yosys features) we can also simply force
the upper 8 bits of ``a`` and ``b`` to zero for the :cmd:ref:`sat` call, as is
done below.
the upper 8 bits of ``a`` and ``b`` to zero for the `sat` call, as is done
below.
.. todo:: replace inline code
@ -705,18 +700,18 @@ command:
sat -seq 6 -show y -show d -set-init-undef \
-max_undef -set-at 4 y 1 -set-at 5 y 2 -set-at 6 y 3
The ``-seq 6`` option instructs the :cmd:ref:`sat` command to solve a sequential
problem in 6 time steps. (Experiments with lower number of steps have show that
at least 3 cycles are necessary to bring the circuit in a state from which the
sequence 1, 2, 3 can be produced.)
The ``-seq 6`` option instructs the `sat` command to solve a sequential problem
in 6 time steps. (Experiments with lower number of steps have show that at least
3 cycles are necessary to bring the circuit in a state from which the sequence
1, 2, 3 can be produced.)
The ``-set-init-undef`` option tells the :cmd:ref:`sat` command to initialize
all registers to the undef (``x``) state. The way the ``x`` state is treated in
The ``-set-init-undef`` option tells the `sat` command to initialize all
registers to the undef (``x``) state. The way the ``x`` state is treated in
Verilog will ensure that the solution will work for any initial state.
The ``-max_undef`` option instructs the :cmd:ref:`sat` command to find a
solution with a maximum number of undefs. This way we can see clearly which
inputs bits are relevant to the solution.
The ``-max_undef`` option instructs the `sat` command to find a solution with a
maximum number of undefs. This way we can see clearly which inputs bits are
relevant to the solution.
Finally the three ``-set-at`` options add constraints for the ``y`` signal to
play the 1, 2, 3 sequence, starting with time step 4.
@ -807,7 +802,7 @@ is the only way of setting the ``s1`` and ``s2`` registers to a known value. The
input values for the other steps are a bit harder to work out manually, but the
SAT solver finds the correct solution in an instant.
There is much more to write about the :cmd:ref:`sat` command. For example, there
is a set of options that can be used to performs sequential proofs using
temporal induction :cite:p:`een2003temporal`. The command ``help sat`` can be
used to print a list of all options with short descriptions of their functions.
There is much more to write about the `sat` command. For example, there is a set
of options that can be used to performs sequential proofs using temporal
induction :cite:p:`een2003temporal`. The command ``help sat`` can be used to
print a list of all options with short descriptions of their functions.

3
docs/source/using_yosys/more_scripting/model_checking.rst
View file

@ -17,8 +17,7 @@ passes in Yosys.
Other applications include checking if a module conforms to interface standards.
The :cmd:ref:`sat` command in Yosys can be used to perform Symbolic Model
Checking.
The `sat` command in Yosys can be used to perform Symbolic Model Checking.
Checking techmap
~~~~~~~~~~~~~~~~

88
docs/source/using_yosys/more_scripting/selections.rst
View file

@ -9,33 +9,33 @@ The selection framework
.. todo:: reduce overlap with :doc:`/getting_started/scripting_intro` select section
The :cmd:ref:`select` command can be used to create a selection for subsequent
commands. For example:
The `select` command can be used to create a selection for subsequent commands.
For example:
.. code:: yoscrypt
select foobar # select the module foobar
delete # delete selected objects
Normally the :cmd:ref:`select` command overwrites a previous selection. The
commands :yoscrypt:`select -add` and :yoscrypt:`select -del` can be used to add
or remove objects from the current selection.
Normally the `select` command overwrites a previous selection. The commands
:yoscrypt:`select -add` and :yoscrypt:`select -del` can be used to add or remove
objects from the current selection.
The command :yoscrypt:`select -clear` can be used to reset the selection to the
default, which is a complete selection of everything in the current module.
This selection framework can also be used directly in many other commands.
Whenever a command has ``[selection]`` as last argument in its usage help, this
means that it will use the engine behind the :cmd:ref:`select` command to
evaluate additional arguments and use the resulting selection instead of the
selection created by the last :cmd:ref:`select` command.
means that it will use the engine behind the `select` command to evaluate
additional arguments and use the resulting selection instead of the selection
created by the last `select` command.
For example, the command :cmd:ref:`delete` will delete everything in the current
For example, the command `delete` will delete everything in the current
selection; while :yoscrypt:`delete foobar` will only delete the module foobar.
If no :cmd:ref:`select` command has been made, then the "current selection" will
be the whole design.
If no `select` command has been made, then the "current selection" will be the
whole design.
.. note:: Many of the examples on this page make use of the :cmd:ref:`show`
.. note:: Many of the examples on this page make use of the `show`
command to visually demonstrate the effect of selections. For a more
detailed look at this command, refer to :ref:`interactive_show`.
@ -59,8 +59,8 @@ Module and design context
^^^^^^^^^^^^^^^^^^^^^^^^^
Commands can be executed in *module/* or *design/* context. Until now, all
commands have been executed in design context. The :cmd:ref:`cd` command can be
used to switch to module context.
commands have been executed in design context. The `cd` command can be used to
switch to module context.
In module context, all commands only effect the active module. Objects in the
module are selected without the ``<module_name>/`` prefix. For example:
@ -91,7 +91,7 @@ Special patterns can be used to select by object property or type. For example:
a:foobar=42`
- select all modules with the attribute ``blabla`` set: :yoscrypt:`select
A:blabla`
- select all $add cells from the module foo: :yoscrypt:`select foo/t:$add`
- select all `$add` cells from the module foo: :yoscrypt:`select foo/t:$add`
A complete list of pattern expressions can be found in :doc:`/cmd/select`.
@ -101,12 +101,12 @@ Operations on selections
Combining selections
^^^^^^^^^^^^^^^^^^^^
The :cmd:ref:`select` command is actually much more powerful than it might seem
at first glance. When it is called with multiple arguments, each argument is
evaluated and pushed separately on a stack. After all arguments have been
processed it simply creates the union of all elements on the stack. So
:yoscrypt:`select t:$add a:foo` will select all ``$add`` cells and all objects
with the ``foo`` attribute set:
The `select` command is actually much more powerful than it might seem at first
glance. When it is called with multiple arguments, each argument is evaluated
and pushed separately on a stack. After all arguments have been processed it
simply creates the union of all elements on the stack. So :yoscrypt:`select
t:$add a:foo` will select all `$add` cells and all objects with the ``foo``
attribute set:
.. literalinclude:: /code_examples/selections/foobaraddsub.v
:caption: Test module for operations on selections
@ -126,7 +126,7 @@ ineffective way of selecting the interesting part of the design. Special
arguments can be used to combine the elements on the stack. For example the
``%i`` arguments pops the last two elements from the stack, intersects them, and
pushes the result back on the stack. So :yoscrypt:`select t:$add a:foo %i` will
select all ``$add`` cells that have the ``foo`` attribute set:
select all `$add` cells that have the ``foo`` attribute set:
.. code-block::
:caption: Output for command ``select t:$add a:foo %i -list`` on :numref:`foobaraddsub`
@ -190,7 +190,7 @@ Selecting logic cones
:numref:`sumprod_01` shows what is called the ``input cone`` of ``sum``, i.e.
all cells and signals that are used to generate the signal ``sum``. The ``%ci``
action can be used to select the input cones of all object in the top selection
in the stack maintained by the :cmd:ref:`select` command.
in the stack maintained by the `select` command.
As with the ``%x`` action, these commands broaden the selection by one "step".
But this time the operation only works against the direction of data flow. That
@ -220,11 +220,11 @@ The following sequence of diagrams demonstrates this step-wise expansion:
Output of :yoscrypt:`show prod %ci %ci %ci` on :numref:`sumprod`
Notice the subtle difference between :yoscrypt:`show prod %ci` and
:yoscrypt:`show prod %ci %ci`. Both images show the ``$mul`` cell driven by
some inputs ``$3_Y`` and ``c``. However it is not until the second image,
having called ``%ci`` the second time, that :cmd:ref:`show` is able to
distinguish between ``$3_Y`` being a wire and ``c`` being an input. We can see
this better with the :cmd:ref:`dump` command instead:
:yoscrypt:`show prod %ci %ci`. Both images show the `$mul` cell driven by some
inputs ``$3_Y`` and ``c``. However it is not until the second image, having
called ``%ci`` the second time, that `show` is able to distinguish between
``$3_Y`` being a wire and ``c`` being an input. We can see this better with the
`dump` command instead:
.. literalinclude:: /code_examples/selections/sumprod.out
:language: RTLIL
@ -241,8 +241,8 @@ be a bit dull. So there is a shortcut for that: the number of iterations can be
appended to the action. So for example the action ``%ci3`` is identical to
performing the ``%ci`` action three times.
The action ``%ci*`` performs the ``%ci`` action over and over again until it
has no effect anymore.
The action ``%ci*`` performs the ``%ci`` action over and over again until it has
no effect anymore.
.. _advanced_logic_cones:
@ -264,8 +264,8 @@ source repository.
:name: memdemo_src
:language: verilog
The script :file:`memdemo.ys` is used to generate the images included here. Let's
look at the first section:
The script :file:`memdemo.ys` is used to generate the images included here.
Let's look at the first section:
.. literalinclude:: /code_examples/selections/memdemo.ys
:caption: Synthesizing :ref:`memdemo_src`
@ -276,8 +276,8 @@ look at the first section:
This loads :numref:`memdemo_src` and synthesizes the included module. Note that
this code can be copied and run directly in a Yosys command line session,
provided :file:`memdemo.v` is in the same directory. We can now change to the
``memdemo`` module with ``cd memdemo``, and call :cmd:ref:`show` to see the
diagram in :numref:`memdemo_00`.
``memdemo`` module with ``cd memdemo``, and call `show` to see the diagram in
:numref:`memdemo_00`.
.. figure:: /_images/code_examples/selections/memdemo_00.*
:class: width-helper invert-helper
@ -296,7 +296,7 @@ cones`_ from above, we can use :yoscrypt:`show y %ci2`:
Output of :yoscrypt:`show y %ci2`
From this we would learn that ``y`` is driven by a ``$dff cell``, that ``y`` is
From this we would learn that ``y`` is driven by a `$dff` cell, that ``y`` is
connected to the output port ``Q``, that the ``clk`` signal goes into the
``CLK`` input port of the cell, and that the data comes from an auto-generated
wire into the input ``D`` of the flip-flop cell (indicated by the ``$`` at the
@ -313,7 +313,7 @@ inputs. To add a pattern we add a colon followed by the pattern to the ``%ci``
action. The pattern itself starts with ``-`` or ``+``, indicating if it is an
include or exclude pattern, followed by an optional comma separated list of cell
types, followed by an optional comma separated list of port names in square
brackets. In this case, we want to exclude the ``S`` port of the ``$mux`` cell
brackets. In this case, we want to exclude the ``S`` port of the `$mux` cell
type with :yoscrypt:`show y %ci5:-$mux[S]`:
.. figure:: /_images/code_examples/selections/memdemo_03.*
@ -334,7 +334,7 @@ multiplexer select inputs and flip-flop cells:
Output of ``show y %ci2:+$dff[Q,D] %ci*:-$mux[S]:-$dff``
Or we could use :yoscrypt:`show y %ci*:-[CLK,S]:+$dff:+$mux` instead, following
the input cone all the way but only following ``$dff`` and ``$mux`` cells, and
the input cone all the way but only following `$dff` and `$mux` cells, and
ignoring any ports named ``CLK`` or ``S``:
.. TODO:: pending discussion on whether rule ordering is a bug or a feature
@ -371,8 +371,8 @@ selection instead of overwriting it.
select -del reg_42 # but not this one
select -add state %ci # and add more stuff
Within a select expression the token ``%`` can be used to push the previous selection
on the stack.
Within a select expression the token ``%`` can be used to push the previous
selection on the stack.
.. code:: yoscrypt
@ -387,16 +387,16 @@ Storing and recalling selections
The current selection can be stored in memory with the command ``select -set
<name>``. It can later be recalled using ``select @<name>``. In fact, the
``@<name>`` expression pushes the stored selection on the stack maintained by
the :cmd:ref:`select` command. So for example :yoscrypt:`select @foo @bar %i`
will select the intersection between the stored selections ``foo`` and ``bar``.
the `select` command. So for example :yoscrypt:`select @foo @bar %i` will select
the intersection between the stored selections ``foo`` and ``bar``.
In larger investigation efforts it is highly recommended to maintain a script
that sets up relevant selections, so they can easily be recalled, for example
when Yosys needs to be re-run after a design or source code change.
The :cmd:ref:`history` command can be used to list all recent interactive
commands. This feature can be useful for creating such a script from the
commands used in an interactive session.
The `history` command can be used to list all recent interactive commands. This
feature can be useful for creating such a script from the commands used in an
interactive session.
Remember that select expressions can also be used directly as arguments to most
commands. Some commands also accept a single select argument to some options. In

27
docs/source/using_yosys/synthesis/abc.rst
View file

@ -10,20 +10,19 @@ fine-grained optimisation and LUT mapping.
Yosys has two different commands, which both use this logic toolbox, but use it
in different ways.
The :cmd:ref:`abc` pass can be used for both ASIC (e.g. :yoscrypt:`abc
-liberty`) and FPGA (:yoscrypt:`abc -lut`) mapping, but this page will focus on
FPGA mapping.
The `abc` pass can be used for both ASIC (e.g. :yoscrypt:`abc -liberty`) and
FPGA (:yoscrypt:`abc -lut`) mapping, but this page will focus on FPGA mapping.
The :cmd:ref:`abc9` pass generally provides superior mapping quality due to
being aware of combination boxes and DFF and LUT timings, giving it a more
global view of the mapping problem.
The `abc9` pass generally provides superior mapping quality due to being aware
of combination boxes and DFF and LUT timings, giving it a more global view of
the mapping problem.
.. _ABC: https://github.com/berkeley-abc/abc
ABC: the unit delay model, simple and efficient
-----------------------------------------------
The :cmd:ref:`abc` pass uses a highly simplified view of an FPGA:
The `abc` pass uses a highly simplified view of an FPGA:
- An FPGA is made up of a network of inputs that connect through LUTs to a
network of outputs. These inputs may actually be I/O pins, D flip-flops,
@ -126,7 +125,7 @@ guide to the syntax:
By convention, all delays in ``specify`` blocks are in integer picoseconds.
Files containing ``specify`` blocks should be read with the ``-specify`` option
to :cmd:ref:`read_verilog` so that they aren't skipped.
to `read_verilog` so that they aren't skipped.
LUTs
^^^^
@ -145,9 +144,9 @@ DFFs
DFFs should be annotated with an ``(* abc9_flop *)`` attribute, however ABC9 has
some specific requirements for this to be valid: - the DFF must initialise to
zero (consider using :cmd:ref:`dfflegalize` to ensure this). - the DFF cannot
have any asynchronous resets/sets (see the simplification idiom and the Boxes
section for what to do here).
zero (consider using `dfflegalize` to ensure this). - the DFF cannot have any
asynchronous resets/sets (see the simplification idiom and the Boxes section for
what to do here).
It is worth noting that in pure ``abc9`` mode, only the setup and arrival times
are passed to ABC9 (specifically, they are modelled as buffers with the given
@ -158,9 +157,9 @@ Some vendors have universal DFF models which include async sets/resets even when
they're unused. Therefore *the simplification idiom* exists to handle this: by
using a ``techmap`` file to discover flops which have a constant driver to those
asynchronous controls, they can be mapped into an intermediate, simplified flop
which qualifies as an ``(* abc9_flop *)``, ran through :cmd:ref:`abc9`, and then
mapped back to the original flop. This is used in :cmd:ref:`synth_intel_alm` and
:cmd:ref:`synth_quicklogic` for the PolarPro3.
which qualifies as an ``(* abc9_flop *)``, ran through `abc9`, and then mapped
back to the original flop. This is used in `synth_intel_alm` and
`synth_quicklogic` for the PolarPro3.
DFFs are usually specified to have setup constraints against the clock on the
input signals, and an arrival time for the ``Q`` output.

14
docs/source/using_yosys/synthesis/cell_libs.rst
View file

@ -54,7 +54,7 @@ Our circuit now looks like this:
:class: width-helper invert-helper
:name: counter-hierarchy
``counter`` after :cmd:ref:`hierarchy`
``counter`` after `hierarchy`
Coarse-grain representation
~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -82,7 +82,7 @@ Logic gate mapping
.. figure:: /_images/code_examples/intro/counter_02.*
:class: width-helper invert-helper
``counter`` after :cmd:ref:`techmap`
``counter`` after `techmap`
Mapping to hardware
~~~~~~~~~~~~~~~~~~~
@ -98,11 +98,11 @@ our internal cell library will be mapped to:
:name: mycells-lib
:caption: :file:`mycells.lib`
Recall that the Yosys built-in logic gate types are ``$_NOT_``, ``$_AND_``,
``$_OR_``, ``$_XOR_``, and ``$_MUX_`` with an assortment of dff memory types.
Recall that the Yosys built-in logic gate types are `$_NOT_`, `$_AND_`, `$_OR_`,
`$_XOR_`, and `$_MUX_` with an assortment of dff memory types.
:ref:`mycells-lib` defines our target cells as ``BUF``, ``NOT``, ``NAND``,
``NOR``, and ``DFF``. Mapping between these is performed with the commands
:cmd:ref:`dfflibmap` and :cmd:ref:`abc` as follows:
`dfflibmap` and `abc` as follows:
.. literalinclude:: /code_examples/intro/counter.ys
:language: yoscrypt
@ -117,8 +117,8 @@ The final version of our ``counter`` module looks like this:
``counter`` after hardware cell mapping
Before finally being output as a verilog file with :cmd:ref:`write_verilog`,
which can then be loaded into another tool:
Before finally being output as a verilog file with `write_verilog`, which can
then be loaded into another tool:
.. literalinclude:: /code_examples/intro/counter.ys
:language: yoscrypt

38
docs/source/using_yosys/synthesis/extract.rst
View file

@ -1,13 +1,13 @@
The extract pass
----------------
- Like the :cmd:ref:`techmap` pass, the :cmd:ref:`extract` pass is called with a
map file. It compares the circuits inside the modules of the map file with the
design and looks for sub-circuits in the design that match any of the modules
in the map file.
- If a match is found, the :cmd:ref:`extract` pass will replace the matching
subcircuit with an instance of the module from the map file.
- In a way the :cmd:ref:`extract` pass is the inverse of the techmap pass.
- Like the `techmap` pass, the `extract` pass is called with a map file. It
compares the circuits inside the modules of the map file with the design and
looks for sub-circuits in the design that match any of the modules in the map
file.
- If a match is found, the `extract` pass will replace the matching subcircuit
with an instance of the module from the map file.
- In a way the `extract` pass is the inverse of the techmap pass.
.. todo:: add/expand supporting text, also mention custom pattern matching and
pmgen
@ -25,7 +25,7 @@ Example code can be found in |code_examples/macc|_.
.. figure:: /_images/code_examples/macc/macc_simple_test_00a.*
:class: width-helper invert-helper
before :cmd:ref:`extract`
before `extract`
.. literalinclude:: /code_examples/macc/macc_simple_test.ys
:language: yoscrypt
@ -34,7 +34,7 @@ Example code can be found in |code_examples/macc|_.
.. figure:: /_images/code_examples/macc/macc_simple_test_00b.*
:class: width-helper invert-helper
after :cmd:ref:`extract`
after `extract`
.. literalinclude:: /code_examples/macc/macc_simple_test.v
:language: verilog
@ -68,26 +68,26 @@ The wrap-extract-unwrap method
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Often a coarse-grain element has a constant bit-width, but can be used to
implement operations with a smaller bit-width. For example, a 18x25-bit multiplier
can also be used to implement 16x20-bit multiplication.
implement operations with a smaller bit-width. For example, a 18x25-bit
multiplier can also be used to implement 16x20-bit multiplication.
A way of mapping such elements in coarse grain synthesis is the
wrap-extract-unwrap method:
wrap
Identify candidate-cells in the circuit and wrap them in a cell with a
constant wider bit-width using :cmd:ref:`techmap`. The wrappers use the same
parameters as the original cell, so the information about the original width
of the ports is preserved. Then use the :cmd:ref:`connwrappers` command to
connect up the bit-extended in- and outputs of the wrapper cells.
constant wider bit-width using `techmap`. The wrappers use the same parameters
as the original cell, so the information about the original width of the ports
is preserved. Then use the `connwrappers` command to connect up the
bit-extended in- and outputs of the wrapper cells.
extract
Now all operations are encoded using the same bit-width as the coarse grain
element. The :cmd:ref:`extract` command can be used to replace circuits with
cells of the target architecture.
element. The `extract` command can be used to replace circuits with cells of
the target architecture.
unwrap
The remaining wrapper cell can be unwrapped using :cmd:ref:`techmap`.
The remaining wrapper cell can be unwrapped using `techmap`.
Example: DSP48_MACC
~~~~~~~~~~~~~~~~~~~
@ -127,7 +127,7 @@ Extract: :file:`macc_xilinx_xmap.v`
:caption: :file:`macc_xilinx_xmap.v`
... simply use the same wrapping commands on this module as on the design to
create a template for the :cmd:ref:`extract` command.
create a template for the `extract` command.
Unwrapping multipliers: :file:`macc_xilinx_unwrap_map.v`

67
docs/source/using_yosys/synthesis/fsm.rst
View file

@ -1,14 +1,14 @@
FSM handling
============
The :cmd:ref:`fsm` command identifies, extracts, optimizes (re-encodes), and
The `fsm` command identifies, extracts, optimizes (re-encodes), and
re-synthesizes finite state machines. It again is a macro that calls a series of
other commands:
.. literalinclude:: /code_examples/macro_commands/fsm.ys
:language: yoscrypt
:start-after: #end:
:caption: Passes called by :cmd:ref:`fsm`
:caption: Passes called by `fsm`
See also :doc:`/cmd/fsm`.
@ -18,34 +18,33 @@ general reported technique :cite:p:`fsmextract`.
FSM detection
~~~~~~~~~~~~~
The :cmd:ref:`fsm_detect` pass identifies FSM state registers. It sets the
``\fsm_encoding = "auto"`` attribute on any (multi-bit) wire that matches the
The `fsm_detect` pass identifies FSM state registers. It sets the
``fsm_encoding = "auto"`` attribute on any (multi-bit) wire that matches the
following description:
- Does not already have the ``\fsm_encoding`` attribute.
- Does not already have the ``fsm_encoding`` attribute.
- Is not an output of the containing module.
- Is driven by single ``$dff`` or ``$adff`` cell.
- The ``\D``-Input of this ``$dff`` or ``$adff`` cell is driven by a
multiplexer tree that only has constants or the old state value on its
leaves.
- Is driven by single `$dff` or `$adff` cell.
- The ``D``-Input of this `$dff` or `$adff` cell is driven by a multiplexer
tree that only has constants or the old state value on its leaves.
- The state value is only used in the said multiplexer tree or by simple
relational cells that compare the state value to a constant (usually ``$eq``
relational cells that compare the state value to a constant (usually `$eq`
cells).
This heuristic has proven to work very well. It is possible to overwrite it by
setting ``\fsm_encoding = "auto"`` on registers that should be considered FSM
state registers and setting ``\fsm_encoding = "none"`` on registers that match
setting ``fsm_encoding = "auto"`` on registers that should be considered FSM
state registers and setting ``fsm_encoding = "none"`` on registers that match
the above criteria but should not be considered FSM state registers.
Note however that marking state registers with ``\fsm_encoding`` that are not
Note however that marking state registers with ``fsm_encoding`` that are not
suitable for FSM recoding can cause synthesis to fail or produce invalid
results.
FSM extraction
~~~~~~~~~~~~~~
The :cmd:ref:`fsm_extract` pass operates on all state signals marked with the
(``\fsm_encoding != "none"``) attribute. For each state signal the following
The `fsm_extract` pass operates on all state signals marked with the
(``fsm_encoding != "none"``) attribute. For each state signal the following
information is determined:
- The state registers
@ -64,10 +63,10 @@ information is determined:
The state registers (and asynchronous reset state, if applicable) is simply
determined by identifying the driver for the state signal.
From there the ``$mux-tree`` driving the state register inputs is recursively
traversed. All select inputs are control signals and the leaves of the
``$mux-tree`` are the states. The algorithm fails if a non-constant leaf that is
not the state signal itself is found.
From there the `$mux`\ -tree driving the state register inputs is recursively
traversed. All select inputs are control signals and the leaves of the `$mux`\
-tree are the states. The algorithm fails if a non-constant leaf that is not the
state signal itself is found.
The list of control outputs is initialized with the bits from the state signal.
It is then extended by adding all values that are calculated by cells that
@ -85,8 +84,8 @@ given set of result signals using a set of signal-value assignments. It can also
be passed a list of stop-signals that abort the ConstEval algorithm if the value
of a stop-signal is needed in order to calculate the result signals.
The :cmd:ref:`fsm_extract` pass uses the ConstEval class in the following way to
create a transition table. For each state:
The `fsm_extract` pass uses the ConstEval class in the following way to create a
transition table. For each state:
1. Create a ConstEval object for the module containing the FSM
2. Add all control inputs to the list of stop signals
@ -99,20 +98,19 @@ create a transition table. For each state:
6. If step 4 was successful: Emit transition
Finally a ``$fsm`` cell is created with the generated transition table and added
Finally a `$fsm` cell is created with the generated transition table and added
to the module. This new cell is connected to the control signals and the old
drivers for the control outputs are disconnected.
FSM optimization
~~~~~~~~~~~~~~~~
The :cmd:ref:`fsm_opt` pass performs basic optimizations on ``$fsm`` cells (not
including state recoding). The following optimizations are performed (in this
order):
The `fsm_opt` pass performs basic optimizations on `$fsm` cells (not including
state recoding). The following optimizations are performed (in this order):
- Unused control outputs are removed from the ``$fsm`` cell. The attribute
``\unused_bits`` (that is usually set by the :cmd:ref:`opt_clean` pass) is
used to determine which control outputs are unused.
- Unused control outputs are removed from the `$fsm` cell. The attribute
``unused_bits`` (that is usually set by the `opt_clean` pass) is used to
determine which control outputs are unused.
- Control inputs that are connected to the same driver are merged.
@ -132,11 +130,10 @@ order):
FSM recoding
~~~~~~~~~~~~
The :cmd:ref:`fsm_recode` pass assigns new bit pattern to the states. Usually
this also implies a change in the width of the state signal. At the moment of
this writing only one-hot encoding with all-zero for the reset state is
supported.
The `fsm_recode` pass assigns new bit pattern to the states. Usually this also
implies a change in the width of the state signal. At the moment of this writing
only one-hot encoding with all-zero for the reset state is supported.
The :cmd:ref:`fsm_recode` pass can also write a text file with the changes
performed by it that can be used when verifying designs synthesized by Yosys
using Synopsys Formality.
The `fsm_recode` pass can also write a text file with the changes performed by
it that can be used when verifying designs synthesized by Yosys using Synopsys
Formality.

15
docs/source/using_yosys/synthesis/index.rst
View file

@ -8,17 +8,16 @@ coarse-grain optimizations before being mapped to hard blocks and fine-grain
cells. Most commands in Yosys will target either coarse-grain representation or
fine-grain representation, with only a select few compatible with both states.
Commands such as :cmd:ref:`proc`, :cmd:ref:`fsm`, and :cmd:ref:`memory` rely on
the additional information in the coarse-grain representation, along with a
number of optimizations such as :cmd:ref:`wreduce`, :cmd:ref:`share`, and
:cmd:ref:`alumacc`. :cmd:ref:`opt` provides optimizations which are useful in
both states, while :cmd:ref:`techmap` is used to convert coarse-grain cells
to the corresponding fine-grain representation.
Commands such as `proc`, `fsm`, and `memory` rely on the additional information
in the coarse-grain representation, along with a number of optimizations such as
`wreduce`, `share`, and `alumacc`. `opt` provides optimizations which are
useful in both states, while `techmap` is used to convert coarse-grain cells to
the corresponding fine-grain representation.
Single-bit cells (logic gates, FFs) as well as LUTs, half-adders, and
full-adders make up the bulk of the fine-grain representation and are necessary
for commands such as :cmd:ref:`abc`\ /:cmd:ref:`abc9`, :cmd:ref:`simplemap`,
:cmd:ref:`dfflegalize`, and :cmd:ref:`memory_map`.
for commands such as `abc`\ /`abc9`, `simplemap`, `dfflegalize`, and
`memory_map`.
.. toctree::
:maxdepth: 3

226
docs/source/using_yosys/synthesis/memory.rst
View file

@ -1,32 +1,32 @@
Memory handling
===============
The :cmd:ref:`memory` command
The `memory` command
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In the RTL netlist, memory reads and writes are individual cells. This makes
consolidating the number of ports for a memory easier. The :cmd:ref:`memory`
pass transforms memories to an implementation. Per default that is logic for
address decoders and registers. It also is a macro command that calls the other
common ``memory_*`` passes in a sensible order:
consolidating the number of ports for a memory easier. The `memory` pass
transforms memories to an implementation. Per default that is logic for address
decoders and registers. It also is a macro command that calls the other common
``memory_*`` passes in a sensible order:
.. literalinclude:: /code_examples/macro_commands/memory.ys
:language: yoscrypt
:start-after: #end:
:caption: Passes called by :cmd:ref:`memory`
:caption: Passes called by `memory`
.. todo:: Make ``memory_*`` notes less quick
Some quick notes:
- :cmd:ref:`memory_dff` merges registers into the memory read- and write cells.
- :cmd:ref:`memory_collect` collects all read and write cells for a memory and
- `memory_dff` merges registers into the memory read- and write cells.
- `memory_collect` collects all read and write cells for a memory and
transforms them into one multi-port memory cell.
- :cmd:ref:`memory_map` takes the multi-port memory cell and transforms it to
address decoder logic and registers.
- `memory_map` takes the multi-port memory cell and transforms it to address
decoder logic and registers.
For more information about :cmd:ref:`memory`, such as disabling certain sub
commands, see :doc:`/cmd/memory`.
For more information about `memory`, such as disabling certain sub commands, see
:doc:`/cmd/memory`.
Example
-------
@ -75,22 +75,22 @@ For example:
techmap -map my_memory_map.v
memory_map
:cmd:ref:`memory_libmap` attempts to convert memory cells (``$mem_v2`` etc) into
hardware supported memory using a provided library (:file:`my_memory_map.txt` in the
`memory_libmap` attempts to convert memory cells (`$mem_v2` etc) into hardware
supported memory using a provided library (:file:`my_memory_map.txt` in the
example above). Where necessary, emulation logic is added to ensure functional
equivalence before and after this conversion. :yoscrypt:`techmap -map
my_memory_map.v` then uses :cmd:ref:`techmap` to map to hardware primitives. Any
leftover memory cells unable to be converted are then picked up by
:cmd:ref:`memory_map` and mapped to DFFs and address decoders.
my_memory_map.v` then uses `techmap` to map to hardware primitives. Any leftover
memory cells unable to be converted are then picked up by `memory_map` and
mapped to DFFs and address decoders.
.. note::
More information about what mapping options are available and associated
costs of each can be found by enabling debug outputs. This can be done with
the :cmd:ref:`debug` command, or by using the ``-g`` flag when calling Yosys
to globally enable debug messages.
the `debug` command, or by using the ``-g`` flag when calling Yosys to
globally enable debug messages.
For more on the lib format for :cmd:ref:`memory_libmap`, see
For more on the lib format for `memory_libmap`, see
`passes/memory/memlib.md
<https://github.com/YosysHQ/yosys/blob/main/passes/memory/memlib.md>`_
@ -110,13 +110,15 @@ Notes
Memory kind selection
~~~~~~~~~~~~~~~~~~~~~
The memory inference code will automatically pick target memory primitive based on memory geometry
and features used. Depending on the target, there can be up to four memory primitive classes
available for selection:
The memory inference code will automatically pick target memory primitive based
on memory geometry and features used. Depending on the target, there can be up
to four memory primitive classes available for selection:
- FF RAM (aka logic): no hardware primitive used, memory lowered to a bunch of FFs and multiplexers
- FF RAM (aka logic): no hardware primitive used, memory lowered to a bunch of
FFs and multiplexers
- Can handle arbitrary number of write ports, as long as all write ports are in the same clock domain
- Can handle arbitrary number of write ports, as long as all write ports are
in the same clock domain
- Can handle arbitrary number and kind of read ports
- LUT RAM (aka distributed RAM): uses LUT storage as RAM
@ -131,7 +133,8 @@ available for selection:
- Supported on basically all FPGAs
- Supports only synchronous reads
- Two ports with separate clocks
- Usually supports true dual port (with notable exception of ice40 that only supports SDP)
- Usually supports true dual port (with notable exception of ice40 that only
supports SDP)
- Usually supports asymmetric memories and per-byte write enables
- Several kilobits in size
@ -155,38 +158,43 @@ available for selection:
- Two ports, both with mutually exclusive synchronous read and write
- Single clock
- Will not be automatically selected by memory inference code, needs explicit opt-in via
ram_style attribute
- Will not be automatically selected by memory inference code, needs explicit
opt-in via ram_style attribute
In general, you can expect the automatic selection process to work roughly like this:
In general, you can expect the automatic selection process to work roughly like
this:
- If any read port is asynchronous, only LUT RAM (or FF RAM) can be used.
- If there is more than one write port, only block RAM can be used, and this needs to be a
hardware-supported true dual port pattern
- If there is more than one write port, only block RAM can be used, and this
needs to be a hardware-supported true dual port pattern
- … unless all write ports are in the same clock domain, in which case FF RAM can also be used,
but this is generally not what you want for anything but really small memories
- … unless all write ports are in the same clock domain, in which case FF RAM
can also be used, but this is generally not what you want for anything but
really small memories
- Otherwise, either FF RAM, LUT RAM, or block RAM will be used, depending on memory size
- Otherwise, either FF RAM, LUT RAM, or block RAM will be used, depending on
memory size
This process can be overridden by attaching a ram_style attribute to the memory:
- `(* ram_style = "logic" *)` selects FF RAM
- `(* ram_style = "distributed" *)` selects LUT RAM
- `(* ram_style = "block" *)` selects block RAM
- `(* ram_style = "huge" *)` selects huge RAM
- ``(* ram_style = "logic" *)`` selects FF RAM
- ``(* ram_style = "distributed" *)`` selects LUT RAM
- ``(* ram_style = "block" *)`` selects block RAM
- ``(* ram_style = "huge" *)`` selects huge RAM
It is an error if this override cannot be realized for the given target.
Many alternate spellings of the attribute are also accepted, for compatibility with other software.
Many alternate spellings of the attribute are also accepted, for compatibility
with other software.
Initial data
~~~~~~~~~~~~
Most FPGA targets support initializing all kinds of memory to user-provided values. If explicit
initialization is not used the initial memory value is undefined. Initial data can be provided by
either initial statements writing memory cells one by one of ``$readmemh`` or ``$readmemb`` system
tasks. For an example pattern, see `sr_init`_.
Most FPGA targets support initializing all kinds of memory to user-provided
values. If explicit initialization is not used the initial memory value is
undefined. Initial data can be provided by either initial statements writing
memory cells one by one of ``$readmemh`` or ``$readmemb`` system tasks. For an
example pattern, see `sr_init`_.
.. _wbe:
@ -194,12 +202,13 @@ Write port with byte enables
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Byte enables can be used with any supported pattern
- To ensure that multiple writes will be merged into one port, they need to have disjoint bit
ranges, have the same address, and the same clock
- Any write enable granularity will be accepted (down to per-bit write enables), but using smaller
granularity than natively supported by the target is very likely to be inefficient (eg. using
4-bit bytes on ECP5 will result in either padding the bytes with 5 dummy bits to native 9-bit
units or splitting the RAM into two block RAMs)
- To ensure that multiple writes will be merged into one port, they need to have
disjoint bit ranges, have the same address, and the same clock
- Any write enable granularity will be accepted (down to per-bit write enables),
but using smaller granularity than natively supported by the target is very
likely to be inefficient (eg. using 4-bit bytes on ECP5 will result in either
padding the bytes with 5 dummy bits to native 9-bit units or splitting the RAM
into two block RAMs)
.. code:: verilog
@ -240,7 +249,8 @@ Synchronous SDP with clock domain crossing
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Will result in block RAM or LUT RAM depending on size
- No behavior guarantees in case of simultaneous read and write to the same address
- No behavior guarantees in case of simultaneous read and write to the same
address
.. code:: verilog
@ -261,9 +271,9 @@ Synchronous SDP read first
- The read and write parts can be in the same or different processes.
- Will result in block RAM or LUT RAM depending on size
- As long as the same clock is used for both, yosys will ensure read-first behavior. This may
require extra circuitry on some targets for block RAM. If this is not necessary, use one of the
patterns below.
- As long as the same clock is used for both, yosys will ensure read-first
behavior. This may require extra circuitry on some targets for block RAM. If
this is not necessary, use one of the patterns below.
.. code:: verilog
@ -281,8 +291,8 @@ Synchronous SDP read first
Synchronous SDP with undefined collision behavior
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Like above, but the read value is undefined when read and write ports target the same address in
the same cycle
- Like above, but the read value is undefined when read and write ports target
the same address in the same cycle
.. code:: verilog
@ -322,8 +332,8 @@ Synchronous SDP with write-first behavior
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Will result in block RAM or LUT RAM depending on size
- May use additional circuitry for block RAM if write-first is not natively supported. Will always
use additional circuitry for LUT RAM.
- May use additional circuitry for block RAM if write-first is not natively
supported. Will always use additional circuitry for LUT RAM.
.. code:: verilog
@ -343,7 +353,8 @@ Synchronous SDP with write-first behavior
Synchronous SDP with write-first behavior (alternate pattern)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- This pattern is supported for compatibility, but is much less flexible than the above
- This pattern is supported for compatibility, but is much less flexible than
the above
.. code:: verilog
@ -378,8 +389,10 @@ Synchronous single-port RAM with mutually exclusive read/write
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Will result in single-port block RAM or LUT RAM depending on size
- This is the correct pattern to infer ice40 SPRAM (with manual ram_style selection)
- On targets that don't support read/write block RAM ports (eg. ice40), will result in SDP block RAM instead
- This is the correct pattern to infer ice40 SPRAM (with manual ram_style
selection)
- On targets that don't support read/write block RAM ports (eg. ice40), will
result in SDP block RAM instead
- For block RAM, will use "NO_CHANGE" mode if available
.. code:: verilog
@ -396,12 +409,14 @@ Synchronous single-port RAM with mutually exclusive read/write
Synchronous single-port RAM with read-first behavior
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Will only result in single-port block RAM when read-first behavior is natively supported;
otherwise, SDP RAM with additional circuitry will be used
- Many targets (Xilinx, ECP5, …) can only natively support read-first/write-first single-port RAM
(or TDP RAM) where the write_enable signal implies the read_enable signal (ie. can never write
without reading). The memory inference code will run a simple SAT solver on the control signals to
determine if this is the case, and insert emulation circuitry if it cannot be easily proven.
- Will only result in single-port block RAM when read-first behavior is natively
supported; otherwise, SDP RAM with additional circuitry will be used
- Many targets (Xilinx, ECP5, …) can only natively support
read-first/write-first single-port RAM (or TDP RAM) where the write_enable
signal implies the read_enable signal (ie. can never write without reading).
The memory inference code will run a simple SAT solver on the control signals
to determine if this is the case, and insert emulation circuitry if it cannot
be easily proven.
.. code:: verilog
@ -418,7 +433,8 @@ Synchronous single-port RAM with write-first behavior
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Will result in single-port block RAM or LUT RAM when supported
- Block RAMs will require extra circuitry if write-first behavior not natively supported
- Block RAMs will require extra circuitry if write-first behavior not natively
supported
.. code:: verilog
@ -440,8 +456,8 @@ Synchronous read port with initial value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Initial read port values can be combined with any other supported pattern
- If block RAM is used and initial read port values are not natively supported by the target, small
emulation circuit will be inserted
- If block RAM is used and initial read port values are not natively supported
by the target, small emulation circuit will be inserted
.. code:: verilog
@ -459,10 +475,11 @@ Synchronous read port with initial value
Read register reset patterns
----------------------------
Resets can be combined with any other supported pattern (except that synchronous reset and
asynchronous reset cannot both be used on a single read port). If block RAM is used and the
selected reset (synchronous or asynchronous) is used but not natively supported by the target, small
emulation circuitry will be inserted.
Resets can be combined with any other supported pattern (except that synchronous
reset and asynchronous reset cannot both be used on a single read port). If
block RAM is used and the selected reset (synchronous or asynchronous) is used
but not natively supported by the target, small emulation circuitry will be
inserted.
Synchronous reset, reset priority over enable
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -520,22 +537,26 @@ Synchronous read port with asynchronous reset
Asymmetric memory patterns
--------------------------
To construct an asymmetric memory (memory with read/write ports of differing widths):
To construct an asymmetric memory (memory with read/write ports of differing
widths):
- Declare the memory with the width of the narrowest intended port
- Split all wide ports into multiple narrow ports
- To ensure the wide ports will be correctly merged:
- For the address, use a concatenation of actual address in the high bits and a constant in the
low bits
- Ensure the actual address is identical for all ports belonging to the wide port
- For the address, use a concatenation of actual address in the high bits and
a constant in the low bits
- Ensure the actual address is identical for all ports belonging to the wide
port
- Ensure that clock is identical
- For read ports, ensure that enable/reset signals are identical (for write ports, the enable
signal may vary — this will result in using the byte enable functionality)
- For read ports, ensure that enable/reset signals are identical (for write
ports, the enable signal may vary — this will result in using the byte
enable functionality)
Asymmetric memory is supported on all targets, but may require emulation circuitry where not
natively supported. Note that when the memory is larger than the underlying block RAM primitive,
hardware asymmetric memory support is likely not to be used even if present as it is more expensive.
Asymmetric memory is supported on all targets, but may require emulation
circuitry where not natively supported. Note that when the memory is larger
than the underlying block RAM primitive, hardware asymmetric memory support is
likely not to be used even if present as it is more expensive.
.. _wide_sr:
@ -615,20 +636,25 @@ Wide write port
True dual port (TDP) patterns
-----------------------------
- Many different variations of true dual port memory can be created by combining two single-port RAM
patterns on the same memory
- When TDP memory is used, memory inference code has much less maneuver room to create requested
semantics compared to individual single-port patterns (which can end up lowered to SDP memory
where necessary) — supported patterns depend strongly on the target
- In particular, when both ports have the same clock, it's likely that "undefined collision" mode
needs to be manually selected to enable TDP memory inference
- The examples below are non-exhaustive — many more combinations of port types are possible
- Note: if two write ports are in the same process, this defines a priority relation between them
(if both ports are active in the same clock, the later one wins). On almost all targets, this will
result in a bit of extra circuitry to ensure the priority semantics. If this is not what you want,
put them in separate processes.
- Many different variations of true dual port memory can be created by combining
two single-port RAM patterns on the same memory
- When TDP memory is used, memory inference code has much less maneuver room to
create requested semantics compared to individual single-port patterns (which
can end up lowered to SDP memory where necessary) — supported patterns depend
strongly on the target
- In particular, when both ports have the same clock, it's likely that
"undefined collision" mode needs to be manually selected to enable TDP memory
inference
- The examples below are non-exhaustive — many more combinations of port types
are possible
- Note: if two write ports are in the same process, this defines a priority
relation between them (if both ports are active in the same clock, the later
one wins). On almost all targets, this will result in a bit of extra circuitry
to ensure the priority semantics. If this is not what you want, put them in
separate processes.
- Priority is not supported when using the verific front end and any priority semantics are ignored.
- Priority is not supported when using the verific front end and any priority
semantics are ignored.
TDP with different clocks, exclusive read/write
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -654,7 +680,8 @@ TDP with different clocks, exclusive read/write
TDP with same clock, read-first behavior
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- This requires hardware inter-port read-first behavior, and will only work on some targets (Xilinx, Nexus)
- This requires hardware inter-port read-first behavior, and will only work on
some targets (Xilinx, Nexus)
.. code:: verilog
@ -677,9 +704,10 @@ TDP with same clock, read-first behavior
TDP with multiple read ports
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- The combination of a single write port with an arbitrary amount of read ports is supported on all
targets — if a multi-read port primitive is available (like Xilinx RAM64M), it'll be used as
appropriate. Otherwise, the memory will be automatically split into multiple primitives.
- The combination of a single write port with an arbitrary amount of read ports
is supported on all targets — if a multi-read port primitive is available
(like Xilinx RAM64M), it'll be used as appropriate. Otherwise, the memory
will be automatically split into multiple primitives.
.. code:: verilog

144
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View file

@ -6,32 +6,32 @@ This chapter outlines these optimizations.
.. todo:: "outlines these optimizations" or "outlines *some*.."?
The :cmd:ref:`opt` macro command
The `opt` macro command
--------------------------------
The Yosys pass :cmd:ref:`opt` runs a number of simple optimizations. This
includes removing unused signals and cells and const folding. It is recommended
to run this pass after each major step in the synthesis script. As listed in
The Yosys pass `opt` runs a number of simple optimizations. This includes
removing unused signals and cells and const folding. It is recommended to run
this pass after each major step in the synthesis script. As listed in
:doc:`/cmd/opt`, this macro command calls the following ``opt_*`` commands:
.. literalinclude:: /code_examples/macro_commands/opt.ys
:language: yoscrypt
:start-after: #end:
:caption: Passes called by :cmd:ref:`opt`
:caption: Passes called by `opt`
.. _adv_opt_expr:
Constant folding and simple expression rewriting - :cmd:ref:`opt_expr`
Constant folding and simple expression rewriting - `opt_expr`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. todo:: unsure if this is too much detail and should be in :doc:`/yosys_internals/index`
This pass performs constant folding on the internal combinational cell types
described in :doc:`/yosys_internals/formats/cell_library`. This means a cell
with all constant inputs is replaced with the constant value this cell drives.
In some cases this pass can also optimize cells with some constant inputs.
described in :doc:`/cell_index`. This means a cell with all
constant inputs is replaced with the constant value this cell drives. In some
cases this pass can also optimize cells with some constant inputs.
.. table:: Const folding rules for ``$_AND_`` cells as used in :cmd:ref:`opt_expr`.
.. table:: Const folding rules for `$_AND_` cells as used in `opt_expr`.
:name: tab:opt_expr_and
:align: center
@ -54,7 +54,7 @@ In some cases this pass can also optimize cells with some constant inputs.
========= ========= ===========
:numref:`Table %s <tab:opt_expr_and>` shows the replacement rules used for
optimizing an ``$_AND_`` gate. The first three rules implement the obvious const
optimizing an `$_AND_` gate. The first three rules implement the obvious const
folding rules. Note that 'any' might include dynamic values calculated by other
parts of the circuit. The following three lines propagate undef (X) states.
These are the only three cases in which it is allowed to propagate an undef
@ -66,33 +66,33 @@ substitutions are possible they are performed first, in the hope that the 'any'
will change to an undef value or a 1 and therefore the output can be set to
undef.
The last two lines simply replace an ``$_AND_`` gate with one constant-1 input
The last two lines simply replace an `$_AND_` gate with one constant-1 input
with a buffer.
Besides this basic const folding the :cmd:ref:`opt_expr` pass can replace 1-bit
wide ``$eq`` and ``$ne`` cells with buffers or not-gates if one input is
constant. Equality checks may also be reduced in size if there are redundant
bits in the arguments (i.e. bits which are constant on both inputs). This can,
for example, result in a 32-bit wide constant like ``255`` being reduced to the
8-bit value of ``8'11111111`` if the signal being compared is only 8-bit as in
Besides this basic const folding the `opt_expr` pass can replace 1-bit wide
`$eq` and `$ne` cells with buffers or not-gates if one input is constant.
Equality checks may also be reduced in size if there are redundant bits in the
arguments (i.e. bits which are constant on both inputs). This can, for example,
result in a 32-bit wide constant like ``255`` being reduced to the 8-bit value
of ``8'11111111`` if the signal being compared is only 8-bit as in
:ref:`addr_gen_clean` of :doc:`/getting_started/example_synth`.
The :cmd:ref:`opt_expr` pass is very conservative regarding optimizing ``$mux``
cells, as these cells are often used to model decision-trees and breaking these
trees can interfere with other optimizations.
The `opt_expr` pass is very conservative regarding optimizing `$mux` cells, as
these cells are often used to model decision-trees and breaking these trees can
interfere with other optimizations.
.. literalinclude:: /code_examples/opt/opt_expr.ys
:language: Verilog
:start-after: read_verilog <<EOT
:end-before: EOT
:caption: example verilog for demonstrating :cmd:ref:`opt_expr`
:caption: example verilog for demonstrating `opt_expr`
.. figure:: /_images/code_examples/opt/opt_expr.*
:class: width-helper invert-helper
Before and after :cmd:ref:`opt_expr`
Before and after `opt_expr`
Merging identical cells - :cmd:ref:`opt_merge`
Merging identical cells - `opt_merge`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass performs trivial resource sharing. This means that this pass
@ -100,22 +100,22 @@ identifies cells with identical inputs and replaces them with a single instance
of the cell.
The option ``-nomux`` can be used to disable resource sharing for multiplexer
cells (``$mux`` and ``$pmux``.) This can be useful as it prevents multiplexer
trees to be merged, which might prevent :cmd:ref:`opt_muxtree` to identify
possible optimizations.
cells (`$mux` and `$pmux`.) This can be useful as it prevents multiplexer trees
to be merged, which might prevent `opt_muxtree` to identify possible
optimizations.
.. literalinclude:: /code_examples/opt/opt_merge.ys
:language: Verilog
:start-after: read_verilog <<EOT
:end-before: EOT
:caption: example verilog for demonstrating :cmd:ref:`opt_merge`
:caption: example verilog for demonstrating `opt_merge`
.. figure:: /_images/code_examples/opt/opt_merge.*
:class: width-helper invert-helper
Before and after :cmd:ref:`opt_merge`
Before and after `opt_merge`
Removing never-active branches from multiplexer tree - :cmd:ref:`opt_muxtree`
Removing never-active branches from multiplexer tree - `opt_muxtree`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass optimizes trees of multiplexer cells by analyzing the select inputs.
@ -125,95 +125,97 @@ Consider the following simple example:
:language: Verilog
:start-after: read_verilog <<EOT
:end-before: EOT
:caption: example verilog for demonstrating :cmd:ref:`opt_muxtree`
:caption: example verilog for demonstrating `opt_muxtree`
The output can never be ``c``, as this would require ``a`` to be 1 for the outer
multiplexer and 0 for the inner multiplexer. The :cmd:ref:`opt_muxtree` pass
detects this contradiction and replaces the inner multiplexer with a constant 1,
yielding the logic for ``y = a ? b : d``.
multiplexer and 0 for the inner multiplexer. The `opt_muxtree` pass detects this
contradiction and replaces the inner multiplexer with a constant 1, yielding the
logic for ``y = a ? b : d``.
.. figure:: /_images/code_examples/opt/opt_muxtree.*
:class: width-helper invert-helper
Before and after :cmd:ref:`opt_muxtree`
Before and after `opt_muxtree`
Simplifying large MUXes and AND/OR gates - :cmd:ref:`opt_reduce`
Simplifying large MUXes and AND/OR gates - `opt_reduce`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is a simple optimization pass that identifies and consolidates identical
input bits to ``$reduce_and`` and ``$reduce_or`` cells. It also sorts the input
bits to ease identification of shareable ``$reduce_and`` and ``$reduce_or``
cells in other passes.
input bits to `$reduce_and` and `$reduce_or` cells. It also sorts the input bits
to ease identification of shareable `$reduce_and` and `$reduce_or` cells in
other passes.
This pass also identifies and consolidates identical inputs to multiplexer
cells. In this case the new shared select bit is driven using a ``$reduce_or``
cells. In this case the new shared select bit is driven using a `$reduce_or`
cell that combines the original select bits.
Lastly this pass consolidates trees of ``$reduce_and`` cells and trees of
``$reduce_or`` cells to single large ``$reduce_and`` or ``$reduce_or`` cells.
Lastly this pass consolidates trees of `$reduce_and` cells and trees of
`$reduce_or` cells to single large `$reduce_and` or `$reduce_or` cells.
These three simple optimizations are performed in a loop until a stable result
is produced.
Merging mutually exclusive cells with shared inputs - :cmd:ref:`opt_share`
Merging mutually exclusive cells with shared inputs - `opt_share`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass identifies mutually exclusive cells of the same type that:
a. share an input signal, and
b. drive the same ``$mux``, ``$_MUX_``, or ``$pmux`` multiplexing cell,
b. drive the same `$mux`, `$_MUX_`, or `$pmux` multiplexing cell,
allowing the cell to be merged and the multiplexer to be moved from
multiplexing its output to multiplexing the non-shared input signals.
allowing the cell to be merged and the multiplexer to be moved from multiplexing
its output to multiplexing the non-shared input signals.
.. literalinclude:: /code_examples/opt/opt_share.ys
:language: Verilog
:start-after: read_verilog <<EOT
:end-before: EOT
:caption: example verilog for demonstrating :cmd:ref:`opt_share`
:caption: example verilog for demonstrating `opt_share`
.. figure:: /_images/code_examples/opt/opt_share.*
:class: width-helper invert-helper
Before and after :cmd:ref:`opt_share`
Before and after `opt_share`
When running :cmd:ref:`opt` in full, the original ``$mux`` (labeled ``$3``) is
optimized away by :cmd:ref:`opt_expr`.
When running `opt` in full, the original `$mux` (labeled ``$3``) is optimized
away by `opt_expr`.
Performing DFF optimizations - :cmd:ref:`opt_dff`
Performing DFF optimizations - `opt_dff`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass identifies single-bit d-type flip-flops (``$_DFF_``, ``$dff``, and
``$adff`` cells) with a constant data input and replaces them with a constant
driver. It can also merge clock enables and synchronous reset multiplexers,
removing unused control inputs.
.. todo:: ``$_DFF_`` isn't a valid cell
This pass identifies single-bit d-type flip-flops (`$_DFF_`, `$dff`, and `$adff`
cells) with a constant data input and replaces them with a constant driver. It
can also merge clock enables and synchronous reset multiplexers, removing unused
control inputs.
Called with ``-nodffe`` and ``-nosdff``, this pass is used to prepare a design
for :doc:`/using_yosys/synthesis/fsm`.
Removing unused cells and wires - :cmd:ref:`opt_clean` pass
Removing unused cells and wires - `opt_clean` pass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass identifies unused signals and cells and removes them from the design.
It also creates an ``\unused_bits`` attribute on wires with unused bits. This
It also creates an ``unused_bits`` attribute on wires with unused bits. This
attribute can be used for debugging or by other optimization passes.
When to use :cmd:ref:`opt` or :cmd:ref:`clean`
When to use `opt` or `clean`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Usually it does not hurt to call :cmd:ref:`opt` after each regular command in
the synthesis script. But it increases the synthesis time, so it is favourable
to only call :cmd:ref:`opt` when an improvement can be achieved.
Usually it does not hurt to call `opt` after each regular command in the
synthesis script. But it increases the synthesis time, so it is favourable to
only call `opt` when an improvement can be achieved.
It is generally a good idea to call :cmd:ref:`opt` before inherently expensive
commands such as :cmd:ref:`sat` or :cmd:ref:`freduce`, as the possible gain is
much higher in these cases as the possible loss.
It is generally a good idea to call `opt` before inherently expensive commands
such as `sat` or `freduce`, as the possible gain is much higher in these cases
as the possible loss.
The :cmd:ref:`clean` command, which is an alias for :cmd:ref:`opt_clean` with
fewer outputs, on the other hand is very fast and many commands leave a mess
(dangling signal wires, etc). For example, most commands do not remove any wires
or cells. They just change the connections and depend on a later call to clean
to get rid of the now unused objects. So the occasional ``;;``, which itself is
an alias for :cmd:ref:`clean`, is a good idea in every synthesis script, e.g:
The `clean` command, which is an alias for `opt_clean` with fewer outputs, on
the other hand is very fast and many commands leave a mess (dangling signal
wires, etc). For example, most commands do not remove any wires or cells. They
just change the connections and depend on a later call to clean to get rid of
the now unused objects. So the occasional ``;;``, which itself is an alias for
`clean`, is a good idea in every synthesis script, e.g:
.. code-block:: yoscrypt
@ -227,4 +229,4 @@ Other optimizations
- :doc:`/cmd/wreduce`
- :doc:`/cmd/peepopt`
- :doc:`/cmd/share`
- :cmd:ref:`abc` and :cmd:ref:`abc9`, see also: :doc:`abc`.
- `abc` and `abc9`, see also: :doc:`abc`.

20
docs/source/using_yosys/synthesis/proc.rst
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@ -5,23 +5,23 @@ Converting process blocks
:language: yoscrypt
The Verilog frontend converts ``always``-blocks to RTL netlists for the
expressions and "processess" for the control- and memory elements. The
:cmd:ref:`proc` command then transforms these "processess" to netlists of RTL
multiplexer and register cells. It also is a macro command that calls the other
``proc_*`` commands in a sensible order:
expressions and "processess" for the control- and memory elements. The `proc`
command then transforms these "processess" to netlists of RTL multiplexer and
register cells. It also is a macro command that calls the other ``proc_*``
commands in a sensible order:
.. literalinclude:: /code_examples/macro_commands/proc.ys
:language: yoscrypt
:start-after: #end:
:caption: Passes called by :cmd:ref:`proc`
:caption: Passes called by `proc`
After all the ``proc_*`` commands, :cmd:ref:`opt_expr` is called. This can be
disabled by calling :yoscrypt:`proc -noopt`. For more information about
:cmd:ref:`proc`, such as disabling certain sub commands, see :doc:`/cmd/proc`.
After all the ``proc_*`` commands, `opt_expr` is called. This can be disabled by
calling :yoscrypt:`proc -noopt`. For more information about `proc`, such as
disabling certain sub commands, see :doc:`/cmd/proc`.
Many commands can not operate on modules with "processess" in them. Usually a
call to :cmd:ref:`proc` is the first command in the actual synthesis procedure
after design elaboration.
call to `proc` is the first command in the actual synthesis procedure after
design elaboration.
Example
^^^^^^^

2
docs/source/using_yosys/synthesis/synth.rst
View file

@ -38,7 +38,7 @@ In addition to the above hardware-specific synth commands, there is also
getting into any architecture-specific mappings or optimizations. Among other
things, this is useful for design verification.
The following commands are executed by the :cmd:ref:`prep` command:
The following commands are executed by the `prep` command:
.. literalinclude:: /cmd/prep.rst
:start-at: begin:

4
docs/source/using_yosys/synthesis/techmap_synth.rst
View file

@ -29,8 +29,8 @@ provided implementation.
When no map file is provided, techmap uses a built-in map file that maps the
Yosys RTL cell types to the internal gate library used by Yosys. The curious
reader may find this map file as `techlibs/common/techmap.v` in the Yosys source
tree.
reader may find this map file as :file:`techlibs/common/techmap.v` in the Yosys
source tree.
Additional features have been added to techmap to allow for conditional mapping
of cells (see :doc:`/cmd/techmap`). This can for example be useful if the target

23
docs/source/yosys_internals/extending_yosys/extensions.rst
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@ -11,17 +11,17 @@ Writing extensions
This chapter contains some bits and pieces of information about programming
yosys extensions. Don't be afraid to ask questions on the YosysHQ Slack.
The `guidelines/` directory of the Yosys source code contains notes on various
aspects of Yosys development. In particular, the files GettingStarted and
CodingStyle may be of interest.
The :file:`guidelines/` directory of the Yosys source code contains notes on
various aspects of Yosys development. In particular, the files GettingStarted
and CodingStyle may be of interest.
.. todo:: what's in guidelines/GettingStarted that's missing from the manual?
Quick guide
-----------
Code examples from this section are included in the
|code_examples/extensions|_ directory of the Yosys source code.
Code examples from this section are included in the |code_examples/extensions|_
directory of the Yosys source code.
.. |code_examples/extensions| replace:: :file:`docs/source/code_examples/extensions`
.. _code_examples/extensions: https://github.com/YosysHQ/yosys/tree/main/docs/source/code_examples/extensions
@ -35,7 +35,7 @@ about the internal data storage format used in Yosys and the classes that it
provides.
This document will focus on the much simpler version of RTLIL left after the
commands :cmd:ref:`proc` and :cmd:ref:`memory` (or :yoscrypt:`memory -nomap`):
commands `proc` and `memory` (or :yoscrypt:`memory -nomap`):
.. figure:: /_images/internals/simplified_rtlil.*
:class: width-helper invert-helper
@ -56,10 +56,9 @@ It is possible to only work on this simpler version:
}
When trying to understand what a command does, creating a small test case to
look at the output of :cmd:ref:`dump` and :cmd:ref:`show` before and after the
command has been executed can be helpful.
:doc:`/using_yosys/more_scripting/selections` has more information on using
these commands.
look at the output of `dump` and `show` before and after the command has been
executed can be helpful. :doc:`/using_yosys/more_scripting/selections` has more
information on using these commands.
Creating a command
~~~~~~~~~~~~~~~~~~
@ -151,8 +150,8 @@ Most commands modify existing modules, not create new ones.
When modifying existing modules, stick to the following DOs and DON'Ts:
- Do not remove wires. Simply disconnect them and let a successive
:cmd:ref:`clean` command worry about removing it.
- Do not remove wires. Simply disconnect them and let a successive `clean`
command worry about removing it.
- Use ``module->fixup_ports()`` after changing the ``port_*`` properties of
wires.
- You can safely remove cells or change the ``connections`` property of a cell,

2
docs/source/yosys_internals/flow/overview.rst
View file

@ -20,7 +20,7 @@ given in :doc:`/yosys_internals/formats/rtlil_rep`.
There is also a text representation of the RTLIL data structure that can be
parsed using the RTLIL Frontend which is described in
:doc:`/yosys_internals/formats/rtlil_text`.
:doc:`/appendix/rtlil_text`.
The design data may then be transformed using a series of passes that all
operate on the RTLIL representation of the design.

40
docs/source/yosys_internals/flow/verilog_frontend.rst
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@ -599,16 +599,16 @@ The proc pass
The ProcessGenerator converts a behavioural model in AST representation to a
behavioural model in ``RTLIL::Process`` representation. The actual conversion
from a behavioural model to an RTL representation is performed by the
:cmd:ref:`proc` pass and the passes it launches:
from a behavioural model to an RTL representation is performed by the `proc`
pass and the passes it launches:
- | :cmd:ref:`proc_clean` and :cmd:ref:`proc_rmdead`
- | `proc_clean` and `proc_rmdead`
| These two passes just clean up the ``RTLIL::Process`` structure. The
:cmd:ref:`proc_clean` pass removes empty parts (eg. empty assignments) from
the process and :cmd:ref:`proc_rmdead` detects and removes unreachable
branches from the process's decision trees.
`proc_clean` pass removes empty parts (eg. empty assignments) from the
process and `proc_rmdead` detects and removes unreachable branches from the
process's decision trees.
- | :cmd:ref:`proc_arst`
- | `proc_arst`
| This pass detects processes that describe d-type flip-flops with
asynchronous resets and rewrites the process to better reflect what they
are modelling: Before this pass, an asynchronous reset has two
@ -616,22 +616,22 @@ from a behavioural model to an RTL representation is performed by the
reset path. After this pass the sync rule for the reset is level-sensitive
and the top-level ``RTLIL::SwitchRule`` has been removed.
- | :cmd:ref:`proc_mux`
| This pass converts the ``RTLIL::CaseRule``/\ ``RTLIL::SwitchRule``-tree to a
tree of multiplexers per written signal. After this, the ``RTLIL::Process``
structure only contains the ``RTLIL::SyncRule`` s that describe the output
registers.
- | `proc_mux`
| This pass converts the ``RTLIL::CaseRule``/\ ``RTLIL::SwitchRule``-tree to
a tree of multiplexers per written signal. After this, the
``RTLIL::Process`` structure only contains the ``RTLIL::SyncRule`` s that
describe the output registers.
- | :cmd:ref:`proc_dff`
- | `proc_dff`
| This pass replaces the ``RTLIL::SyncRule``\ s to d-type flip-flops (with
asynchronous resets if necessary).
- | :cmd:ref:`proc_dff`
| This pass replaces the ``RTLIL::MemWriteAction``\ s with ``$memwr`` cells.
- | `proc_dff`
| This pass replaces the ``RTLIL::MemWriteAction``\ s with `$memwr` cells.
- | :cmd:ref:`proc_clean`
| A final call to :cmd:ref:`proc_clean` removes the now empty
``RTLIL::Process`` objects.
- | `proc_clean`
| A final call to `proc_clean` removes the now empty ``RTLIL::Process``
objects.
Performing these last processing steps in passes instead of in the Verilog
frontend has two important benefits:
@ -646,8 +646,8 @@ to extend the actual Verilog frontend.
.. todo:: Synthesizing Verilog arrays
Add some information on the generation of ``$memrd`` and ``$memwr`` cells and
how they are processed in the memory pass.
Add some information on the generation of `$memrd` and `$memwr` cells and how
they are processed in the memory pass.
.. todo:: Synthesizing parametric designs

1241
docs/source/yosys_internals/formats/cell_library.rst
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58
docs/source/yosys_internals/formats/index.rst
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@ -1,13 +1,59 @@
Internal formats
================
.. todo:: brief overview for the internal formats index
Yosys uses two different internal formats. The first is used to store an
abstract syntax tree (AST) of a Verilog input file. This format is simply called
AST and is generated by the Verilog Frontend. This data structure is consumed by
a subsystem called AST Frontend [1]_. This AST Frontend then generates a design
in Yosys' main internal format, the
Register-Transfer-Level-Intermediate-Language (RTLIL) representation. It does
that by first performing a number of simplifications within the AST
representation and then generating RTLIL from the simplified AST data structure.
The RTLIL representation is used by all passes as input and outputs. This has
the following advantages over using different representational formats between
different passes:
- The passes can be rearranged in a different order and passes can be removed
or inserted.
- Passes can simply pass-thru the parts of the design they don't change without
the need to convert between formats. In fact Yosys passes output the same
data structure they received as input and performs all changes in place.
- All passes use the same interface, thus reducing the effort required to
understand a pass when reading the Yosys source code, e.g. when adding
additional features.
The RTLIL representation is basically a netlist representation with the
following additional features:
- An internal cell library with fixed-function cells to represent RTL datapath
and register cells as well as logical gate-level cells (single-bit gates and
registers).
- Support for multi-bit values that can use individual bits from wires as well
as constant bits to represent coarse-grain netlists.
- Support for basic behavioural constructs (if-then-else structures and
multi-case switches with a sensitivity list for updating the outputs).
- Support for multi-port memories.
The use of RTLIL also has the disadvantage of having a very powerful format
between all passes, even when doing gate-level synthesis where the more advanced
features are not needed. In order to reduce complexity for passes that operate
on a low-level representation, these passes check the features used in the input
RTLIL and fail to run when unsupported high-level constructs are used. In such
cases a pass that transforms the higher-level constructs to lower-level
constructs must be called from the synthesis script first.
.. toctree::
:maxdepth: 3
:maxdepth: 3
overview
rtlil_rep
rtlil_text
cell_library
rtlil_rep
.. [1]
In Yosys the term pass is only used to refer to commands that operate on the
RTLIL data structure.

53
docs/source/yosys_internals/formats/overview.rst
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@ -1,53 +0,0 @@
Format overview
===============
Yosys uses two different internal formats. The first is used to store an
abstract syntax tree (AST) of a Verilog input file. This format is simply called
AST and is generated by the Verilog Frontend. This data structure is consumed by
a subsystem called AST Frontend [1]_. This AST Frontend then generates a design
in Yosys' main internal format, the
Register-Transfer-Level-Intermediate-Language (RTLIL) representation. It does
that by first performing a number of simplifications within the AST
representation and then generating RTLIL from the simplified AST data structure.
The RTLIL representation is used by all passes as input and outputs. This has
the following advantages over using different representational formats between
different passes:
- The passes can be rearranged in a different order and passes can be removed
or inserted.
- Passes can simply pass-thru the parts of the design they don't change without
the need to convert between formats. In fact Yosys passes output the same
data structure they received as input and performs all changes in place.
- All passes use the same interface, thus reducing the effort required to
understand a pass when reading the Yosys source code, e.g. when adding
additional features.
The RTLIL representation is basically a netlist representation with the
following additional features:
- An internal cell library with fixed-function cells to represent RTL datapath
and register cells as well as logical gate-level cells (single-bit gates and
registers).
- Support for multi-bit values that can use individual bits from wires as well
as constant bits to represent coarse-grain netlists.
- Support for basic behavioural constructs (if-then-else structures and
multi-case switches with a sensitivity list for updating the outputs).
- Support for multi-port memories.
The use of RTLIL also has the disadvantage of having a very powerful format
between all passes, even when doing gate-level synthesis where the more advanced
features are not needed. In order to reduce complexity for passes that operate
on a low-level representation, these passes check the features used in the input
RTLIL and fail to run when unsupported high-level constructs are used. In such
cases a pass that transforms the higher-level constructs to lower-level
constructs must be called from the synthesis script first.
.. [1]
In Yosys the term pass is only used to refer to commands that operate on the
RTLIL data structure.

53
docs/source/yosys_internals/formats/rtlil_rep.rst
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@ -76,11 +76,10 @@ This has three advantages:
- Second, the information about which identifiers were originally provided by
the user is always available which can help guide some optimizations. For
example, :cmd:ref:`opt_clean` tries to preserve signals with a user-provided
name but doesn't hesitate to delete signals that have auto-generated names
when they just duplicate other signals. Note that this can be overridden
with the `-purge` option to also delete internal nets with user-provided
names.
example, `opt_clean` tries to preserve signals with a user-provided name but
doesn't hesitate to delete signals that have auto-generated names when they
just duplicate other signals. Note that this can be overridden with the
``-purge`` option to also delete internal nets with user-provided names.
- Third, the delicate job of finding suitable auto-generated public visible
names is deferred to one central location. Internally auto-generated names
@ -204,8 +203,8 @@ A "signal" is everything that can be applied to a cell port. I.e.
- | Concatenations of the above
| 1em For example: ``{16'd1337, mywire[15:8]}``
The ``RTLIL::SigSpec`` data type is used to represent signals. The ``RTLIL::Cell``
object contains one ``RTLIL::SigSpec`` for each cell port.
The ``RTLIL::SigSpec`` data type is used to represent signals. The
``RTLIL::Cell`` object contains one ``RTLIL::SigSpec`` for each cell port.
In addition, connections between wires are represented using a pair of
``RTLIL::SigSpec`` objects. Such pairs are needed in different locations.
@ -234,9 +233,9 @@ control logic of the behavioural code. Let's consider a simple example:
q <= d;
endmodule
In this example there is no data path and therefore the ``RTLIL::Module`` generated
by the frontend only contains a few ``RTLIL::Wire`` objects and an ``RTLIL::Process`` .
The ``RTLIL::Process`` in RTLIL syntax:
In this example there is no data path and therefore the ``RTLIL::Module``
generated by the frontend only contains a few ``RTLIL::Wire`` objects and an
``RTLIL::Process``. The ``RTLIL::Process`` in RTLIL syntax:
.. code:: RTLIL
:number-lines:
@ -320,8 +319,8 @@ trees before further processing them.
One of the first actions performed on a design in RTLIL representation in most
synthesis scripts is identifying asynchronous resets. This is usually done using
the :cmd:ref:`proc_arst` pass. This pass transforms the above example to the
following ``RTLIL::Process``:
the `proc_arst` pass. This pass transforms the above example to the following
``RTLIL::Process``:
.. code:: RTLIL
:number-lines:
@ -340,9 +339,9 @@ following ``RTLIL::Process``:
end
This pass has transformed the outer ``RTLIL::SwitchRule`` into a modified
``RTLIL::SyncRule`` object for the ``\reset`` signal. Further processing converts the
``RTLIL::Process`` into e.g. a d-type flip-flop with asynchronous reset and a
multiplexer for the enable signal:
``RTLIL::SyncRule`` object for the ``\reset`` signal. Further processing
converts the ``RTLIL::Process`` into e.g. a d-type flip-flop with asynchronous
reset and a multiplexer for the enable signal:
.. code:: RTLIL
:number-lines:
@ -365,11 +364,11 @@ multiplexer for the enable signal:
connect \Y $0\q[0:0]
end
Different combinations of passes may yield different results. Note that
``$adff`` and ``$mux`` are internal cell types that still need to be mapped to
cell types from the target cell library.
Different combinations of passes may yield different results. Note that `$adff`
and `$mux` are internal cell types that still need to be mapped to cell types
from the target cell library.
Some passes refuse to operate on modules that still contain ``RTLIL::Process``
Some passes refuse to operate on modules that still contain ``RTLIL::Process``
objects as the presence of these objects in a module increases the complexity.
Therefore the passes to translate processes to a netlist of cells are usually
called early in a synthesis script. The proc pass calls a series of other passes
@ -389,25 +388,25 @@ A memory object has the following properties:
- The width of an addressable word
- The size of the memory in number of words
All read accesses to the memory are transformed to ``$memrd`` cells and all
write accesses to ``$memwr`` cells by the language frontend. These cells consist
of independent read- and write-ports to the memory. Memory initialization is
transformed to ``$meminit`` cells by the language frontend. The ``\MEMID``
All read accesses to the memory are transformed to `$memrd` cells and all write
accesses to `$memwr` cells by the language frontend. These cells consist of
independent read- and write-ports to the memory. Memory initialization is
transformed to `$meminit` cells by the language frontend. The ``\MEMID``
parameter on these cells is used to link them together and to the
``RTLIL::Memory`` object they belong to.
The rationale behind using separate cells for the individual ports versus
creating a large multiport memory cell right in the language frontend is that
the separate ``$memrd`` and ``$memwr`` cells can be consolidated using resource
the separate `$memrd` and `$memwr` cells can be consolidated using resource
sharing. As resource sharing is a non-trivial optimization problem where
different synthesis tasks can have different requirements it lends itself to do
the optimisation in separate passes and merge the ``RTLIL::Memory`` objects and
``$memrd`` and ``$memwr`` cells to multiport memory blocks after resource
sharing is completed.
`$memrd` and `$memwr` cells to multiport memory blocks after resource sharing is
completed.
The memory pass performs this conversion and can (depending on the options
passed to it) transform the memories directly to d-type flip-flops and address
logic or yield multiport memory blocks (represented using ``$mem`` cells).
logic or yield multiport memory blocks (represented using `$mem` cells).
See :ref:`sec:memcells` for details about the memory cell types.

14
docs/source/yosys_internals/techmap.rst
View file

@ -1,9 +1,9 @@
Techmap by example
------------------
As a quick recap, the :cmd:ref:`techmap` command replaces cells in the design
with implementations given as Verilog code (called "map files"). It can replace
Yosys' internal cell types (such as ``$or``) as well as user-defined cell types.
As a quick recap, the `techmap` command replaces cells in the design with
implementations given as Verilog code (called "map files"). It can replace
Yosys' internal cell types (such as `$or`) as well as user-defined cell types.
- Verilog parameters are used extensively to customize the internal cell types.
- Additional special parameters are used by techmap to communicate meta-data to
@ -87,15 +87,15 @@ Scripting in map modules
- You can even call techmap recursively!
- Example use-cases:
- Using always blocks in map module: call :cmd:ref:`proc`
- Perform expensive optimizations (such as :cmd:ref:`freduce`) on cells
- Using always blocks in map module: call `proc`
- Perform expensive optimizations (such as `freduce`) on cells
where this is known to work well.
- Interacting with custom commands.
.. note:: PROTIP:
Commands such as :cmd:ref:`shell`, ``show -pause``, and :cmd:ref:`dump` can
be used in the ``_TECHMAP_DO_*`` scripts for debugging map modules.
Commands such as `shell`, ``show -pause``, and `dump` can be used in the
``_TECHMAP_DO_*`` scripts for debugging map modules.
Example:

73
docs/util/YoscryptLexer.py
View file

@ -1,73 +0,0 @@
from pygments.lexer import RegexLexer, bygroups, include
from pygments.token import (Comment, Error, Keyword, Name, Number, Operator,
String, Whitespace)
__all__ = ['YoscryptLexer']
class YoscryptLexer(RegexLexer):
name = 'Yosys Script'
aliases = ['yoscrypt']
filenames = ['*.ys']
tokens = {
'common': [
(r'\s+', Whitespace),
(r'#.*', Comment.Single),
(r'"', String, 'string'),
(r'(\d+)(\')([bdho]? ?\w+)', bygroups(Number, Operator, Number)),
(r'(\d+\.\d+)', Number.Float),
(r'(\d+)', Number),
(r'(\$[A-Za-z_0-9]*)', Name.Builtin),
(r'([A-Za-z_][A-Za-z_0-9\.\\/:-]*)', Name),
(r'(\[)(-\S*)(\])', # optional command
bygroups(Operator, Name.Attribute, Operator)),
(r'([\[<]\w*[\]>])', Name), # arguments
(r'[\{\}\|=\[\],]', Operator),
(r'.', Comment),
],
'root': [
(r'([A-Za-z_][A-Za-z_0-9]*)', Keyword, 'command'),
(r'(-[A-Za-z_][A-Za-z_0-9]*)', Name.Attribute, 'command'), # shortcut for options
include('common'),
],
'command': [
(r'(-[A-Za-z_][A-Za-z_0-9]*)', Name.Attribute),
(r'\+/[^\s]+', Name.Class),
(r'$', Whitespace, '#pop'),
(r';(?=\s)', Operator, '#pop'),
(r';{2,3}(?=\s)', Name.Class, '#pop'),
(r';{1,3}', Error, '#pop'),
(r'([ANwismctparn]:)', Keyword.Type, 'pattern'),
(r'@', Keyword.Type),
(r'%(x|ci|co)e?', Keyword.Type, 'expansion'),
(r'%[%nuidDcasmMCR]?', Keyword.Type),
(r'/', Operator),
include('common'),
],
'pattern': [
(r'<<', Name), # Not an operator
(r'(=|<|<=|>|>=)', Operator),
(r':', Keyword.Type),
(r'$', Whitespace, '#pop:2'),
(r'\s+', Whitespace, '#pop'),
include('common'),
],
'expansion': [
(r'$', Name.Class, '#pop:2'),
(r';(?=\s)', Operator, '#pop:2'),
(r';{2,3}(?=\s)', Name.Class, '#pop:2'),
(r'\s', Whitespace, '#pop'),
(r'[0-9\*]{1,3}', Number),
(r'[:+-,\[\]]', Operator),
include('common'),
],
'string': [
(r'"', String, '#pop'),
(r'\\([\\abfnrtv"\']|x[a-fA-F0-9]{2,4}|[0-7]{1,3})', String.Escape),
(r'[^\\"\n]+', String), # all other characters
(r'(\\)(\n)', bygroups(String.Escape, Whitespace)), # line continuation
(r'\\', String), # stray backslash
]
}

415
docs/util/cellref.py Normal file
View file

@ -0,0 +1,415 @@
#!/usr/bin/env python3
from __future__ import annotations
from dataclasses import dataclass
import json
from pathlib import Path, PosixPath, WindowsPath
import re
from typing import Any
from sphinx.application import Sphinx
from sphinx.ext import autodoc
from sphinx.ext.autodoc import Documenter
from sphinx.util import logging
logger = logging.getLogger(__name__)
# cell signature
cell_ext_sig_re = re.compile(
r'''^ ([^:\s]+::)? # optional group or file name
([\w$._]+?) # module name
(?:\.([\w_]+))? # optional: thing name
(::[\w_]+)? # attribute
\s* $ # and nothing more
''', re.VERBOSE)
@dataclass
class YosysCell:
name: str
title: str
ports: str
source: str
desc: str
code: str
inputs: list[str]
outputs: list[str]
properties: list[str]
class YosysCellGroupDocumenter(Documenter):
objtype = 'cellgroup'
priority = 10
object: tuple[str, list[str]]
lib_key = 'groups'
option_spec = {
'caption': autodoc.annotation_option,
'members': autodoc.members_option,
'source': autodoc.bool_option,
'linenos': autodoc.bool_option,
}
__cell_lib: dict[str, list[str] | dict[str]] | None = None
@property
def cell_lib(self) -> dict[str, list[str] | dict[str]]:
if not self.__cell_lib:
self.__cell_lib = {}
cells_obj: dict[str, dict[str, list[str] | dict[str]]]
try:
with open(self.config.cells_json, "r") as f:
cells_obj = json.loads(f.read())
except FileNotFoundError:
logger.warning(
f"unable to find cell lib at {self.config.cells_json}",
type = 'cellref',
subtype = 'cell_lib'
)
else:
for (name, obj) in cells_obj.get(self.lib_key, {}).items():
self.__cell_lib[name] = obj
return self.__cell_lib
@classmethod
def can_document_member(
cls,
member: Any,
membername: str,
isattr: bool,
parent: Any
) -> bool:
return False
def parse_name(self) -> bool:
if not self.options.caption:
self.content_indent = ''
self.fullname = self.modname = self.name
return True
def import_object(self, raiseerror: bool = False) -> bool:
# get cell
try:
self.object = (self.modname, self.cell_lib[self.modname])
except KeyError:
if raiseerror:
raise
return False
self.real_modname = self.modname
return True
def get_sourcename(self) -> str:
return self.env.doc2path(self.env.docname)
def format_name(self) -> str:
return self.options.caption or ''
def format_signature(self, **kwargs: Any) -> str:
return self.modname
def add_directive_header(self, sig: str) -> None:
domain = getattr(self, 'domain', 'cell')
directive = getattr(self, 'directivetype', 'group')
name = self.format_name()
sourcename = self.get_sourcename()
cell_list = self.object
# cell definition
self.add_line(f'.. {domain}:{directive}:: {sig}', sourcename)
self.add_line(f' :caption: {name}', sourcename)
if self.options.noindex:
self.add_line(' :noindex:', sourcename)
def add_content(self, more_content: Any | None) -> None:
# groups have no native content
# add additional content (e.g. from document), if present
if more_content:
for line, src in zip(more_content.data, more_content.items):
self.add_line(line, src[0], src[1])
def filter_members(
self,
members: list[tuple[str, Any]],
want_all: bool
) -> list[tuple[str, Any, bool]]:
return [(x[0], x[1], False) for x in members]
def get_object_members(
self,
want_all: bool
) -> tuple[bool, list[tuple[str, Any]]]:
ret: list[tuple[str, str]] = []
if want_all:
for member in self.object[1]:
ret.append((member, self.modname))
else:
memberlist = self.options.members or []
for name in memberlist:
if name in self.object:
ret.append((name, self.modname))
else:
logger.warning(('unknown module mentioned in :members: option: '
f'group {self.modname}, module {name}'),
type='cellref')
return False, ret
def document_members(self, all_members: bool = False) -> None:
want_all = (all_members or
self.options.inherited_members or
self.options.members is autodoc.ALL)
# find out which members are documentable
members_check_module, members = self.get_object_members(want_all)
# document non-skipped members
memberdocumenters: list[tuple[Documenter, bool]] = []
for (mname, member, isattr) in self.filter_members(members, want_all):
classes = [cls for cls in self.documenters.values()
if cls.can_document_member(member, mname, isattr, self)]
if not classes:
# don't know how to document this member
continue
# prefer the documenter with the highest priority
classes.sort(key=lambda cls: cls.priority)
# give explicitly separated module name, so that members
# of inner classes can be documented
full_mname = self.format_signature() + '::' + mname
documenter = classes[-1](self.directive, full_mname, self.indent)
memberdocumenters.append((documenter, isattr))
member_order = self.options.member_order or self.config.autodoc_member_order
memberdocumenters = self.sort_members(memberdocumenters, member_order)
for documenter, isattr in memberdocumenters:
documenter.generate(
all_members=True, real_modname=self.real_modname,
check_module=members_check_module and not isattr)
def generate(
self,
more_content: Any | None = None,
real_modname: str | None = None,
check_module: bool = False,
all_members: bool = False
) -> None:
if not self.parse_name():
# need a cell lib to import from
logger.warning(
f"don't know which cell lib to import for autodocumenting {self.name}",
type = 'cellref'
)
return
if not self.import_object():
logger.warning(
f"unable to load {self.name}",
type = 'cellref'
)
return
# check __module__ of object (for members not given explicitly)
# if check_module:
# if not self.check_module():
# return
sourcename = self.get_sourcename()
self.add_line('', sourcename)
# format the object's signature, if any
try:
sig = self.format_signature()
except Exception as exc:
logger.warning(('error while formatting signature for %s: %s'),
self.fullname, exc, type='cellref')
return
# generate the directive header and options, if applicable
self.add_directive_header(sig)
self.add_line('', sourcename)
# e.g. the module directive doesn't have content
self.indent += self.content_indent
# add all content (from docstrings, attribute docs etc.)
self.add_content(more_content)
# document members, if possible
self.document_members(all_members)
class YosysCellDocumenter(YosysCellGroupDocumenter):
objtype = 'cell'
priority = 15
object: YosysCell
lib_key = 'cells'
@classmethod
def can_document_member(
cls,
member: Any,
membername: str,
isattr: bool,
parent: Any
) -> bool:
if membername == "__source":
return False
if not membername.startswith('$'):
return False
return isinstance(parent, YosysCellGroupDocumenter)
def parse_name(self) -> bool:
try:
matched = cell_ext_sig_re.match(self.name)
group, modname, thing, attribute = matched.groups()
except AttributeError:
logger.warning(('invalid signature for auto%s (%r)') % (self.objtype, self.name),
type='cellref')
return False
self.modname = modname
self.groupname = group or ''
self.attribute = attribute or ''
self.fullname = ((self.modname) + (thing or ''))
return True
def import_object(self, raiseerror: bool = False) -> bool:
if super().import_object(raiseerror):
self.object = YosysCell(self.modname, **self.object[1])
return True
return False
def get_sourcename(self) -> str:
return self.object.source.split(":")[0]
def format_name(self) -> str:
return self.object.name
def format_signature(self, **kwargs: Any) -> str:
return self.groupname + self.fullname + self.attribute
def add_directive_header(self, sig: str) -> None:
domain = getattr(self, 'domain', self.objtype)
directive = getattr(self, 'directivetype', 'def')
name = self.format_name()
sourcename = self.get_sourcename()
cell = self.object
# cell definition
self.add_line(f'.. {domain}:{directive}:: {sig}', sourcename)
# options
opt_attrs = ["title", "properties", ]
for attr in opt_attrs:
val = getattr(cell, attr, None)
if isinstance(val, list):
val = ' '.join(val)
if val:
self.add_line(f' :{attr}: {val}', sourcename)
self.add_line('\n', sourcename)
if self.options.noindex:
self.add_line(' :noindex:', sourcename)
def add_content(self, more_content: Any | None) -> None:
# set sourcename and add content from attribute documentation
sourcename = self.get_sourcename()
startline = int(self.object.source.split(":")[1])
for i, line in enumerate(self.object.desc.splitlines(), startline):
self.add_line(line, sourcename, i)
# add additional content (e.g. from document), if present
if more_content:
for line, src in zip(more_content.data, more_content.items):
self.add_line(line, src[0], src[1])
# fields
self.add_line('\n', sourcename)
field_attrs = ["properties", ]
for field in field_attrs:
attr = getattr(self.object, field, [])
for val in attr:
self.add_line(f':{field} {val}:', sourcename)
def get_object_members(
self,
want_all: bool
) -> tuple[bool, list[tuple[str, Any]]]:
ret: list[tuple[str, str]] = []
if self.options.source:
ret.append(('__source', self.real_modname))
return False, ret
class YosysCellSourceDocumenter(YosysCellDocumenter):
objtype = 'cellsource'
priority = 20
@classmethod
def can_document_member(
cls,
member: Any,
membername: str,
isattr: bool,
parent: Any
) -> bool:
if membername != "__source":
return False
if isinstance(parent, YosysCellDocumenter):
return True
return False
def add_directive_header(self, sig: str) -> None:
domain = getattr(self, 'domain', 'cell')
directive = getattr(self, 'directivetype', 'source')
name = self.format_name()
sourcename = self.get_sourcename()
cell = self.object
# cell definition
self.add_line(f'.. {domain}:{directive}:: {sig}', sourcename)
if self.options.linenos:
self.add_line(f' :source: {cell.source.split(":")[0]}', sourcename)
else:
self.add_line(f' :source: {cell.source}', sourcename)
self.add_line(f' :language: verilog', sourcename)
if self.options.linenos:
startline = int(self.object.source.split(":")[1])
self.add_line(f' :lineno-start: {startline}', sourcename)
if self.options.noindex:
self.add_line(' :noindex:', sourcename)
def add_content(self, more_content: Any | None) -> None:
# set sourcename and add content from attribute documentation
sourcename = self.get_sourcename()
startline = int(self.object.source.split(":")[1])
for i, line in enumerate(self.object.code.splitlines(), startline-1):
self.add_line(line, sourcename, i)
# add additional content (e.g. from document), if present
if more_content:
for line, src in zip(more_content.data, more_content.items):
self.add_line(line, src[0], src[1])
def get_object_members(
self,
want_all: bool
) -> tuple[bool, list[tuple[str, Any]]]:
return False, []
def setup(app: Sphinx) -> dict[str, Any]:
app.add_config_value('cells_json', False, 'html', [Path, PosixPath, WindowsPath])
app.setup_extension('sphinx.ext.autodoc')
app.add_autodocumenter(YosysCellDocumenter)
app.add_autodocumenter(YosysCellSourceDocumenter)
app.add_autodocumenter(YosysCellGroupDocumenter)
return {
'version': '1',
'parallel_read_safe': True,
}

477
docs/util/cmdref.py
View file

@ -1,72 +1,344 @@
# based on https://github.com/ofosos/sphinxrecipes/blob/master/sphinxrecipes/sphinxrecipes.py
# license:
# Copyright 2019 Mark Meyer
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
import docutils
from __future__ import annotations
import re
from typing import cast
from docutils import nodes
import sphinx
from docutils.parsers import rst
from docutils.nodes import Node, Element, system_message
from docutils.parsers.rst import directives
from docutils.parsers.rst.states import Inliner
from sphinx.application import Sphinx
from sphinx.domains import Domain, Index
from sphinx.domains.std import StandardDomain
from sphinx.environment import BuildEnvironment
from sphinx.roles import XRefRole
from sphinx.directives import ObjectDescription
from sphinx.directives.code import container_wrapper
from sphinx.util.nodes import make_refnode
from sphinx.util.docfields import Field
from sphinx import addnodes
class CommandNode(ObjectDescription):
class TocNode(ObjectDescription):
def add_target_and_index(
self,
name: str,
sig: str,
signode: addnodes.desc_signature
) -> None:
idx = ".".join(name.split("::"))
signode['ids'].append(idx)
def _object_hierarchy_parts(self, sig_node: addnodes.desc_signature) -> tuple[str, ...]:
if 'fullname' not in sig_node:
return ()
modname = sig_node.get('module')
fullname = sig_node['fullname']
if modname:
return (modname, *fullname.split('::'))
else:
return tuple(fullname.split('::'))
def _toc_entry_name(self, sig_node: addnodes.desc_signature) -> str:
if not sig_node.get('_toc_parts'):
return ''
config = self.env.app.config
objtype = sig_node.parent.get('objtype')
*parents, name = sig_node['_toc_parts']
if config.toc_object_entries_show_parents == 'domain':
return sig_node.get('tocname', name)
if config.toc_object_entries_show_parents == 'hide':
return name
if config.toc_object_entries_show_parents == 'all':
return '.'.join(parents + [name])
return ''
class CommandNode(TocNode):
"""A custom node that describes a command."""
name = 'cmd'
required_arguments = 1
option_spec = {
'title': directives.unchanged_required,
'title': directives.unchanged,
'tags': directives.unchanged
}
def handle_signature(self, sig, signode: addnodes.desc_signature):
signode['fullname'] = sig
signode += addnodes.desc_addname(text="yosys> help ")
signode += addnodes.desc_name(text=sig)
return sig
return signode['fullname']
def add_target_and_index(self, name_cls, sig, signode):
signode['ids'].append('cmd' + '-' + sig)
idx = type(self).name + '-' + sig
signode['ids'].append(idx)
if 'noindex' not in self.options:
name = "{}.{}.{}".format('cmd', type(self).__name__, sig)
tagmap = self.env.domaindata['cmd']['obj2tag']
name = "{}.{}.{}".format(self.name, type(self).__name__, sig)
tagmap = self.env.domaindata[type(self).name]['obj2tag']
tagmap[name] = list(self.options.get('tags', '').split(' '))
title = self.options.get('title')
titlemap = self.env.domaindata['cmd']['obj2title']
title = self.options.get('title', sig)
titlemap = self.env.domaindata[type(self).name]['obj2title']
titlemap[name] = title
objs = self.env.domaindata['cmd']['objects']
objs = self.env.domaindata[type(self).name]['objects']
# (name, sig, typ, docname, anchor, prio)
objs.append((name,
sig,
title,
type(self).name,
self.env.docname,
'cmd' + '-' + sig,
idx,
0))
class PropNode(TocNode):
name = 'prop'
fieldname = 'props'
def handle_signature(self, sig: str, signode: addnodes.desc_signature):
signode['fullname'] = sig
signode['tocname'] = tocname = sig.split('::')[-1]
signode += addnodes.desc_name(text=tocname)
return signode['fullname']
def add_target_and_index(
self,
name: str,
sig: str,
signode: addnodes.desc_signature
) -> None:
idx = ".".join(name.split("::"))
signode['ids'].append(idx)
if 'noindex' not in self.options:
tocname: str = signode.get('tocname', name)
objs = self.env.domaindata[self.domain]['objects']
# (name, sig, typ, docname, anchor, prio)
objs.append((name,
tocname,
type(self).name,
self.env.docname,
idx,
1))
class CellGroupedField(Field):
"""Custom version of GroupedField which doesn't require content."""
is_grouped = True
list_type = nodes.bullet_list
def __init__(self, name: str, names: tuple[str, ...] = (), label: str = None,
rolename: str = None, can_collapse: bool = False) -> None:
super().__init__(name, names, label, True, rolename)
self.can_collapse = can_collapse
def make_field(self, types: dict[str, list[Node]], domain: str,
items: tuple, env: BuildEnvironment = None,
inliner: Inliner = None, location: Node = None) -> nodes.field:
fieldname = nodes.field_name('', self.label)
listnode = self.list_type()
for fieldarg, content in items:
par = nodes.paragraph()
if fieldarg:
par.extend(self.make_xrefs(self.rolename, domain,
fieldarg, nodes.Text,
env=env, inliner=inliner, location=location))
if len(content) == 1 and (
isinstance(content[0], nodes.Text) or
(isinstance(content[0], nodes.inline) and len(content[0]) == 1 and
isinstance(content[0][0], nodes.Text))):
par += nodes.Text(' -- ')
par += content
listnode += nodes.list_item('', par)
if len(items) == 1 and self.can_collapse:
list_item = cast(nodes.list_item, listnode[0])
fieldbody = nodes.field_body('', list_item[0])
return nodes.field('', fieldname, fieldbody)
fieldbody = nodes.field_body('', listnode)
return nodes.field('', fieldname, fieldbody)
class CellNode(TocNode):
"""A custom node that describes an internal cell."""
name = 'cell'
option_spec = {
'title': directives.unchanged,
'ports': directives.unchanged,
'properties': directives.unchanged,
}
doc_field_types = [
CellGroupedField('props', label='Properties', rolename='prop',
names=('properties', 'property', 'tag', 'tags'),
can_collapse=True),
]
def handle_signature(self, sig: str, signode: addnodes.desc_signature):
signode['fullname'] = sig
signode['tocname'] = tocname = sig.split('::')[-1]
signode += addnodes.desc_addname(text="yosys> help ")
signode += addnodes.desc_name(text=tocname)
return signode['fullname']
def add_target_and_index(
self,
name: str,
sig: str,
signode: addnodes.desc_signature
) -> None:
idx = ".".join(name.split("::"))
signode['ids'].append(idx)
if 'noindex' not in self.options:
tocname: str = signode.get('tocname', name)
title: str = self.options.get('title', sig)
titlemap = self.env.domaindata[self.domain]['obj2title']
titlemap[name] = title
props = self.options.get('properties', '')
if props:
propmap = self.env.domaindata[self.domain]['obj2prop']
propmap[name] = props.split(' ')
objs = self.env.domaindata[self.domain]['objects']
# (name, sig, typ, docname, anchor, prio)
objs.append((name,
tocname,
type(self).name,
self.env.docname,
idx,
0))
def transform_content(self, contentnode: addnodes.desc_content) -> None:
# Add the cell title to the body
if 'title' in self.options:
titlenode = nodes.paragraph()
titlenode += nodes.strong()
titlenode[-1] += nodes.Text(self.options['title'])
contentnode.insert(0, titlenode)
class CellSourceNode(TocNode):
"""A custom code block for including cell source."""
name = 'cellsource'
option_spec = {
"source": directives.unchanged_required,
"language": directives.unchanged_required,
'lineno-start': int,
}
def handle_signature(
self,
sig,
signode: addnodes.desc_signature
) -> str:
language = self.options.get('language')
signode['fullname'] = sig
signode['tocname'] = f"{sig.split('::')[-2]} {language}"
signode += addnodes.desc_name(text="Simulation model")
signode += addnodes.desc_sig_space()
signode += addnodes.desc_addname(text=f'({language})')
return signode['fullname']
def run(self) -> list[Node]:
"""Override run to parse content as a code block"""
if ':' in self.name:
self.domain, self.objtype = self.name.split(':', 1)
else:
self.domain, self.objtype = '', self.name
self.indexnode = addnodes.index(entries=[])
node = addnodes.desc()
node.document = self.state.document
source, line = self.get_source_info()
if line is not None:
line -= 1
self.state.document.note_source(source, line)
node['domain'] = self.domain
# 'desctype' is a backwards compatible attribute
node['objtype'] = node['desctype'] = self.objtype
node['noindex'] = noindex = ('noindex' in self.options)
node['noindexentry'] = ('noindexentry' in self.options)
node['nocontentsentry'] = ('nocontentsentry' in self.options)
if self.domain:
node['classes'].append(self.domain)
node['classes'].append(node['objtype'])
self.names = []
signatures = self.get_signatures()
for sig in signatures:
# add a signature node for each signature in the current unit
# and add a reference target for it
signode = addnodes.desc_signature(sig, '')
self.set_source_info(signode)
node.append(signode)
try:
# name can also be a tuple, e.g. (classname, objname);
# this is strictly domain-specific (i.e. no assumptions may
# be made in this base class)
name = self.handle_signature(sig, signode)
except ValueError:
# signature parsing failed
signode.clear()
signode += addnodes.desc_name(sig, sig)
continue # we don't want an index entry here
finally:
# Private attributes for ToC generation. Will be modified or removed
# without notice.
if self.env.app.config.toc_object_entries:
signode['_toc_parts'] = self._object_hierarchy_parts(signode)
signode['_toc_name'] = self._toc_entry_name(signode)
else:
signode['_toc_parts'] = ()
signode['_toc_name'] = ''
if name not in self.names:
self.names.append(name)
if not noindex:
# only add target and index entry if this is the first
# description of the object with this name in this desc block
self.add_target_and_index(name, sig, signode)
# handle code
code = '\n'.join(self.content)
literal: Element = nodes.literal_block(code, code)
if 'lineno-start' in self.options:
literal['linenos'] = True
literal['highlight_args'] = {
'linenostart': self.options['lineno-start']
}
literal['classes'] += self.options.get('class', [])
literal['language'] = self.options.get('language')
literal = container_wrapper(self, literal, self.options.get('source'))
return [self.indexnode, node, literal]
class CellGroupNode(TocNode):
name = 'cellgroup'
option_spec = {
'caption': directives.unchanged,
}
def add_target_and_index(self, name: str, sig: str, signode: addnodes.desc_signature) -> None:
if self.options.get('caption', ''):
super().add_target_and_index(name, sig, signode)
def handle_signature(
self,
sig,
signode: addnodes.desc_signature
) -> str:
signode['fullname'] = fullname = sig
caption = self.options.get("caption", fullname)
if caption:
signode['tocname'] = caption
signode += addnodes.desc_name(text=caption)
return fullname
class TagIndex(Index):
"""A custom directive that creates an tag matrix."""
"""A custom directive that creates a tag matrix."""
name = 'tag'
localname = 'Tag Index'
@ -107,7 +379,7 @@ class TagIndex(Index):
in self.domain.get_objects()}
tmap = {}
tags = self.domain.data['obj2tag']
tags = self.domain.data[f'obj2{self.name}']
for name, tags in tags.items():
for tag in tags:
tmap.setdefault(tag,[])
@ -123,10 +395,9 @@ class TagIndex(Index):
anchor,
docname, '', typ
))
re = [(k, v) for k, v in sorted(content.items())]
return (re, True)
ret = [(k, v) for k, v in sorted(content.items())]
return (ret, True)
class CommandIndex(Index):
name = 'cmd'
@ -164,23 +435,81 @@ class CommandIndex(Index):
content = {}
items = ((name, dispname, typ, docname, anchor)
for name, dispname, typ, docname, anchor, prio
in self.domain.get_objects())
in self.domain.get_objects()
if typ == self.name)
items = sorted(items, key=lambda item: item[0])
for name, dispname, typ, docname, anchor in items:
lis = content.setdefault('Command', [])
lis = content.setdefault(self.shortname, [])
lis.append((
dispname, 0, docname,
anchor,
'', '', typ
))
re = [(k, v) for k, v in sorted(content.items())]
ret = [(k, v) for k, v in sorted(content.items())]
return (re, True)
return (ret, True)
class CellIndex(CommandIndex):
name = 'cell'
localname = 'Internal cell reference'
shortname = 'Internal cell'
class PropIndex(TagIndex):
"""A custom directive that creates a properties matrix."""
name = 'prop'
localname = 'Property Index'
shortname = 'Prop'
fieldname = 'props'
def generate(self, docnames=None):
content = {}
cells = {name: (dispname, docname, anchor)
for name, dispname, typ, docname, anchor, _
in self.domain.get_objects()
if typ == 'cell'}
props = {name: (dispname, docname, anchor)
for name, dispname, typ, docname, anchor, _
in self.domain.get_objects()
if typ == 'prop'}
tmap: dict[str, list[str]] = {}
tags: dict[str, list[str]] = self.domain.data[f'obj2{self.name}']
for name, tags in tags.items():
for tag in tags:
tmap.setdefault(tag,[])
tmap[tag].append(name)
for tag in sorted(tmap.keys()):
test = re.match(r'^(\w+[_-])', tag)
tag_prefix = test.group(1)
lis = content.setdefault(tag_prefix, [])
try:
dispname, docname, anchor = props[tag]
except KeyError:
dispname = tag
docname = anchor = ''
lis.append((
dispname, 1, docname,
anchor,
'', '', docname or 'unavailable'
))
objlis = tmap[tag]
for objname in sorted(objlis):
dispname, docname, anchor = cells[objname]
lis.append((
dispname, 2, docname,
anchor,
'', '', docname
))
ret = [(k, v) for k, v in sorted(content.items())]
return (ret, True)
class CommandDomain(Domain):
name = 'cmd'
label = 'Command Sample'
label = 'Yosys commands'
roles = {
'ref': XRefRole()
@ -203,7 +532,7 @@ class CommandDomain(Domain):
def get_full_qualified_name(self, node):
"""Return full qualified name for a given node"""
return "{}.{}.{}".format('cmd',
return "{}.{}.{}".format(type(self).name,
type(node).__name__,
node.arguments[0])
@ -229,18 +558,68 @@ class CommandDomain(Domain):
else:
print(f"Missing ref for {target} in {fromdocname} ")
return None
class CellDomain(CommandDomain):
name = 'cell'
label = 'Yosys internal cells'
def setup(app):
roles = CommandDomain.roles.copy()
roles.update({
'prop': XRefRole()
})
directives = {
'def': CellNode,
'defprop': PropNode,
'source': CellSourceNode,
'group': CellGroupNode,
}
indices = {
CellIndex,
PropIndex
}
initial_data = {
'objects': [], # object list
'obj2prop': {}, # name -> properties
'obj2title': {}, # name -> title
}
def get_objects(self):
for obj in self.data['objects']:
yield(obj)
def autoref(name, rawtext: str, text: str, lineno, inliner: Inliner,
options=None, content=None):
role = 'cell:ref' if text[0] == '$' else 'cmd:ref'
if text.startswith("help ") and text.count(' ') == 1:
_, cmd = text.split(' ', 1)
text = f'{text} <{cmd}>'
return inliner.interpreted(rawtext, text, role, lineno)
def setup(app: Sphinx):
app.add_domain(CommandDomain)
app.add_domain(CellDomain)
StandardDomain.initial_data['labels']['commandindex'] =\
('cmd-cmd', '', 'Command Reference')
StandardDomain.initial_data['labels']['tagindex'] =\
('cmd-tag', '', 'Tag Index')
StandardDomain.initial_data['labels']['cellindex'] =\
('cell-cell', '', 'Internal cell reference')
StandardDomain.initial_data['labels']['propindex'] =\
('cell-prop', '', 'Property Index')
StandardDomain.initial_data['anonlabels']['commandindex'] =\
('cmd-cmd', '')
StandardDomain.initial_data['anonlabels']['tagindex'] =\
('cmd-tag', '')
StandardDomain.initial_data['anonlabels']['cellindex'] =\
('cell-cell', '')
StandardDomain.initial_data['anonlabels']['propindex'] =\
('cell-prop', '')
app.add_role('autoref', autoref)
return {'version': '0.1'}
return {'version': '0.2'}

6
kernel/celltypes.h
View file

@ -29,6 +29,8 @@ struct CellType
RTLIL::IdString type;
pool<RTLIL::IdString> inputs, outputs;
bool is_evaluable;
bool is_combinatorial;
bool is_synthesizable;
};
struct CellTypes
@ -56,9 +58,9 @@ struct CellTypes
setup_stdcells_mem();
}
void setup_type(RTLIL::IdString type, const pool<RTLIL::IdString> &inputs, const pool<RTLIL::IdString> &outputs, bool is_evaluable = false)
void setup_type(RTLIL::IdString type, const pool<RTLIL::IdString> &inputs, const pool<RTLIL::IdString> &outputs, bool is_evaluable = false, bool is_combinatorial = false, bool is_synthesizable = false)
{
CellType ct = {type, inputs, outputs, is_evaluable};
CellType ct = {type, inputs, outputs, is_evaluable, is_combinatorial, is_synthesizable};
cell_types[ct.type] = ct;
}

240
kernel/register.cc
View file

@ -19,6 +19,7 @@
#include "kernel/yosys.h"
#include "kernel/satgen.h"
#include "kernel/json.h"
#include <string.h>
#include <stdlib.h>
@ -747,14 +748,44 @@ void Backend::backend_call(RTLIL::Design *design, std::ostream *f, std::string f
design->selection_stack.pop_back();
}
struct SimHelper {
string name;
inline string filesafe_name() {
if (name.at(0) == '$')
if (name.at(1) == '_')
return "gate" + name.substr(1);
else
return "word_" + name.substr(1);
else
return name;
}
string title;
string ports;
string source;
string desc;
string code;
string group;
string ver;
string tags;
};
static bool is_code_getter(string name) {
return *(--(name.end())) == '+';
}
static string get_cell_name(string name) {
return is_code_getter(name) ? name.substr(0, name.length()-1) : name;
}
static struct CellHelpMessages {
dict<string, string> cell_help, cell_code;
dict<string, SimHelper> cell_help;
CellHelpMessages() {
#include "techlibs/common/simlib_help.inc"
#include "techlibs/common/simcells_help.inc"
cell_help.sort();
cell_code.sort();
}
bool contains(string name) { return cell_help.count(get_cell_name(name)) > 0; }
SimHelper get(string name) { return cell_help[get_cell_name(name)]; }
} cell_help_messages;
struct HelpPass : public Pass {
@ -771,7 +802,7 @@ struct HelpPass : public Pass {
log(" help <celltype>+ .... print verilog code for given cell type\n");
log("\n");
}
void write_rst(std::string cmd, std::string title, std::string text)
void write_cmd_rst(std::string cmd, std::string title, std::string text)
{
FILE *f = fopen(stringf("docs/source/cmd/%s.rst", cmd.c_str()).c_str(), "wt");
// make header
@ -864,6 +895,146 @@ struct HelpPass : public Pass {
}
fclose(f);
}
void write_cell_rst(Yosys::SimHelper cell, Yosys::CellType ct)
{
// open
FILE *f = fopen(stringf("docs/source/cell/%s.rst", cell.filesafe_name().c_str()).c_str(), "wt");
// make header
string title_line;
if (cell.title.length())
title_line = stringf("%s - %s", cell.name.c_str(), cell.title.c_str());
else title_line = cell.name;
string underline = "\n";
underline.insert(0, title_line.length(), '=');
fprintf(f, "%s\n", title_line.c_str());
fprintf(f, "%s\n", underline.c_str());
// help text, with cell def for links
fprintf(f, ".. cell:def:: %s\n", cell.name.c_str());
if (cell.title.length())
fprintf(f, " :title: %s\n\n", cell.title.c_str());
else
fprintf(f, " :title: %s\n\n", cell.name.c_str());
std::stringstream ss;
ss << cell.desc;
for (std::string line; std::getline(ss, line, '\n');) {
fprintf(f, " %s\n", line.c_str());
}
// properties
fprintf(f, "\nProperties");
fprintf(f, "\n----------\n\n");
dict<string, bool> prop_dict = {
{"is_evaluable", ct.is_evaluable},
{"is_combinatorial", ct.is_combinatorial},
{"is_synthesizable", ct.is_synthesizable},
};
for (auto &it : prop_dict) {
fprintf(f, "- %s: %s\n", it.first.c_str(), it.second ? "true" : "false");
}
// source code
fprintf(f, "\nSimulation model (Verilog)");
fprintf(f, "\n--------------------------\n\n");
fprintf(f, ".. code-block:: verilog\n");
fprintf(f, " :caption: %s\n\n", cell.source.c_str());
std::stringstream ss2;
ss2 << cell.code;
for (std::string line; std::getline(ss2, line, '\n');) {
fprintf(f, " %s\n", line.c_str());
}
// footer
fprintf(f, "\n.. note::\n\n");
fprintf(f, " This page was auto-generated from the output of\n");
fprintf(f, " ``help %s``.\n", cell.name.c_str());
// close
fclose(f);
}
bool dump_cells_json(PrettyJson &json) {
// init json
json.begin_object();
json.entry("version", "Yosys internal cells");
json.entry("generator", yosys_version_str);
dict<string, vector<string>> groups;
dict<string, pair<SimHelper, CellType>> cells;
// iterate over cells
bool raise_error = false;
for (auto &it : yosys_celltypes.cell_types) {
auto name = it.first.str();
if (cell_help_messages.contains(name)) {
auto cell_help = cell_help_messages.get(name);
if (groups.count(cell_help.group) != 0) {
auto group_cells = &groups.at(cell_help.group);
group_cells->push_back(name);
} else {
auto group_cells = new vector<string>(1, name);
groups.emplace(cell_help.group, *group_cells);
}
auto cell_pair = pair<SimHelper, CellType>(cell_help, it.second);
cells.emplace(name, cell_pair);
} else {
log("ERROR: Missing cell help for cell '%s'.\n", name.c_str());
raise_error |= true;
}
}
for (auto &it : cell_help_messages.cell_help) {
if (cells.count(it.first) == 0) {
log_warning("Found cell model '%s' without matching cell type.\n", it.first.c_str());
}
}
// write to json
json.name("groups"); json.begin_object();
groups.sort();
for (auto &it : groups) {
json.name(it.first.c_str()); json.value(it.second);
}
json.end_object();
json.name("cells"); json.begin_object();
cells.sort();
for (auto &it : cells) {
auto ch = it.second.first;
auto ct = it.second.second;
json.name(ch.name.c_str()); json.begin_object();
json.name("title"); json.value(ch.title);
json.name("ports"); json.value(ch.ports);
json.name("source"); json.value(ch.source);
json.name("desc"); json.value(ch.desc);
json.name("code"); json.value(ch.code);
vector<string> inputs, outputs;
for (auto &input : ct.inputs)
inputs.push_back(input.str());
json.name("inputs"); json.value(inputs);
for (auto &output : ct.outputs)
outputs.push_back(output.str());
json.name("outputs"); json.value(outputs);
vector<string> properties;
// CellType properties
if (ct.is_evaluable) properties.push_back("is_evaluable");
if (ct.is_combinatorial) properties.push_back("is_combinatorial");
if (ct.is_synthesizable) properties.push_back("is_synthesizable");
// SimHelper properties
size_t last = 0; size_t next = 0;
while ((next = ch.tags.find(", ", last)) != string::npos) {
properties.push_back(ch.tags.substr(last, next-last));
last = next + 2;
}
auto final_tag = ch.tags.substr(last);
if (final_tag.size()) properties.push_back(final_tag);
json.name("properties"); json.value(properties);
json.end_object();
}
json.end_object();
json.end_object();
return raise_error;
}
void execute(std::vector<std::string> args, RTLIL::Design*) override
{
if (args.size() == 1) {
@ -896,9 +1067,8 @@ struct HelpPass : public Pass {
else if (args[1] == "-cells") {
log("\n");
for (auto &it : cell_help_messages.cell_help) {
string line = split_tokens(it.second, "\n").at(0);
string cell_name = next_token(line);
log(" %-15s %s\n", cell_name.c_str(), line.c_str());
SimHelper help_cell = it.second;
log(" %-15s %s\n", help_cell.name.c_str(), help_cell.ports.c_str());
}
log("\n");
log("Type 'help <cell_type>' for more information on a cell type.\n");
@ -917,7 +1087,23 @@ struct HelpPass : public Pass {
log("\n");
}
log_streams.pop_back();
write_rst(it.first, it.second->short_help, buf.str());
write_cmd_rst(it.first, it.second->short_help, buf.str());
}
}
// this option is also undocumented as it is for internal use only
else if (args[1] == "-write-rst-cells-manual") {
bool raise_error = false;
for (auto &it : yosys_celltypes.cell_types) {
auto name = it.first.str();
if (cell_help_messages.contains(name)) {
write_cell_rst(cell_help_messages.get(name), it.second);
} else {
log("ERROR: Missing cell help for cell '%s'.\n", name.c_str());
raise_error |= true;
}
}
if (raise_error) {
log_error("One or more cells defined in celltypes.h are missing help documentation.\n");
}
}
else if (pass_register.count(args[1])) {
@ -928,18 +1114,42 @@ struct HelpPass : public Pass {
log("\n");
}
}
else if (cell_help_messages.cell_help.count(args[1])) {
log("%s", cell_help_messages.cell_help.at(args[1]).c_str());
log("Run 'help %s+' to display the Verilog model for this cell type.\n", args[1].c_str());
log("\n");
}
else if (cell_help_messages.cell_code.count(args[1])) {
log("\n");
log("%s", cell_help_messages.cell_code.at(args[1]).c_str());
else if (cell_help_messages.contains(args[1])) {
auto help_cell = cell_help_messages.get(args[1]);
if (is_code_getter(args[1])) {
log("\n");
log("%s\n", help_cell.code.c_str());
} else {
log("\n %s %s\n\n", help_cell.name.c_str(), help_cell.ports.c_str());
if (help_cell.ver == "2" || help_cell.ver == "2a") {
if (help_cell.title != "") log("%s:\n", help_cell.title.c_str());
std::stringstream ss;
ss << help_cell.desc;
for (std::string line; std::getline(ss, line, '\n');) {
if (line != "::") log("%s\n", line.c_str());
}
} else if (help_cell.desc.length()) {
log("%s\n", help_cell.desc.c_str());
} else {
log("No help message for this cell type found.\n");
}
log("\nRun 'help %s+' to display the Verilog model for this cell type.\n", args[1].c_str());
log("\n");
}
}
else
log("No such command or cell type: %s\n", args[1].c_str());
return;
} else if (args.size() == 3) {
if (args[1] == "-dump-cells-json") {
PrettyJson json;
if (!json.write_to_file(args[2]))
log_error("Can't open file `%s' for writing: %s\n", args[2].c_str(), strerror(errno));
if (dump_cells_json(json)) {
log_error("One or more cells defined in celltypes.h are missing help documentation.\n");
}
}
return;
}
help();

106
techlibs/common/cellhelp.py
View file

@ -1,34 +1,100 @@
#!/usr/bin/env python3
from __future__ import annotations
import fileinput
import json
from pathlib import Path
current_help_msg = []
current_module_code = []
current_module_name = None
current_module_signature = None
class SimHelper:
name: str = ""
title: str = ""
ports: str = ""
source: str = ""
desc: list[str]
code: list[str]
group: str = ""
ver: str = "1"
tags: list[str]
def print_current_cell():
print("cell_help[\"%s\"] = %s;" % (current_module_name, "\n".join([json.dumps(line) for line in current_help_msg])))
print("cell_code[\"%s+\"] = %s;" % (current_module_name, "\n".join([json.dumps(line) for line in current_module_code])))
def __init__(self) -> None:
self.desc = []
self.tags = []
def __str__(self) -> str:
printed_fields = [
"name", "title", "ports", "source", "desc", "code", "group", "ver",
"tags",
]
# generate C++ struct
val = f"cell_help[{json.dumps(self.name)}] = "
val += "{\n"
for field in printed_fields:
field_val = getattr(self, field)
if isinstance(field_val, list):
field_val = "\n".join(field_val)
field_val = field_val.strip()
val += f' {json.dumps(field_val)},\n'
val += "};\n"
return val
def simcells_reparse(cell: SimHelper):
# cut manual signature
cell.desc = cell.desc[3:]
# code-block truth table
new_desc = []
indent = ""
for line in cell.desc:
if line.startswith("Truth table:"):
indent = " "
new_desc.pop()
new_desc.extend(["::", ""])
new_desc.append(indent + line)
cell.desc = new_desc
# set version
cell.ver = "2a"
simHelper = SimHelper()
for line in fileinput.input():
line = line.rstrip()
# special comments
if line.startswith("//-"):
current_help_msg.append(line[4:] if len(line) > 4 else "\n")
simHelper.desc.append(line[4:] if len(line) > 4 else "")
elif line.startswith("//* "):
_, key, val = line.split(maxsplit=2)
setattr(simHelper, key, val)
# code parsing
if line.startswith("module "):
current_module_name = line.split()[1].strip("\\")
current_module_signature = " ".join(line.replace("\\", "").replace(";", "").split()[1:])
current_module_code = []
clean_line = line[7:].replace("\\", "").replace(";", "")
simHelper.name, simHelper.ports = clean_line.split(maxsplit=1)
simHelper.code = []
short_filename = Path(fileinput.filename()).name
simHelper.source = f'{short_filename}:{fileinput.filelineno()}'
elif not line.startswith("endmodule"):
line = " " + line
current_module_code.append(line.replace("\t", " "))
try:
simHelper.code.append(line.replace("\t", " "))
except AttributeError:
# no module definition, ignore line
pass
if line.startswith("endmodule"):
if len(current_help_msg) == 0:
current_help_msg.append("\n")
current_help_msg.append(" %s\n" % current_module_signature)
current_help_msg.append("\n")
current_help_msg.append("No help message for this cell type found.\n")
current_help_msg.append("\n")
print_current_cell()
current_help_msg = []
short_filename = Path(fileinput.filename()).name
if simHelper.ver == "1" and short_filename == "simcells.v":
# default simcells parsing
simcells_reparse(simHelper)
# check help
if simHelper.desc and simHelper.ver == "1" and short_filename == "simlib.v" and simHelper.desc[1].startswith(' '):
simHelper.desc.pop(1)
# check group
assert simHelper.group, f"techlibs/common/{simHelper.source}: {simHelper.name} cell missing group"
# dump
print(simHelper)
# new
simHelper = SimHelper()

16
techlibs/common/gen_fine_ffs.py
View file

@ -3,6 +3,7 @@ TEMPLATES = [
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_SR_{S:N|P}{R:N|P}_ (S, R, Q)
//* group reg_latch
//-
//- A set-reset latch with {S:negative|positive} polarity SET and {R:negative|positive} polarity RESET.
//-
@ -28,6 +29,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_FF_ (D, Q)
//* group reg_ff
//-
//- A D-type flip-flop that is clocked from the implicit global clock. (This cell
//- type is usually only used in netlists for formal verification.)
@ -45,6 +47,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFF_{C:N|P}_ (D, C, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop.
//-
@ -65,6 +68,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFFE_{C:N|P}{E:N|P}_ (D, C, E, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {E:negative|positive} polarity enable.
//-
@ -85,6 +89,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFF_{C:N|P}{R:N|P}{V:0|1}_ (D, C, R, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {R:negative|positive} polarity {V:reset|set}.
//-
@ -109,6 +114,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFFE_{C:N|P}{R:N|P}{V:0|1}{E:N|P}_ (D, C, R, E, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {R:negative|positive} polarity {V:reset|set} and {E:negative|positive}
//- polarity clock enable.
@ -134,6 +140,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_ALDFF_{C:N|P}{L:N|P}_ (D, C, L, AD, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {L:negative|positive} polarity async load.
//-
@ -158,6 +165,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_ALDFFE_{C:N|P}{L:N|P}{E:N|P}_ (D, C, L, AD, E, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {L:negative|positive} polarity async load and {E:negative|positive}
//- polarity clock enable.
@ -183,6 +191,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFFSR_{C:N|P}{S:N|P}{R:N|P}_ (C, S, R, D, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {S:negative|positive} polarity set and {R:negative|positive}
//- polarity reset.
@ -211,6 +220,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DFFSRE_{C:N|P}{S:N|P}{R:N|P}{E:N|P}_ (C, S, R, E, D, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {S:negative|positive} polarity set, {R:negative|positive}
//- polarity reset and {E:negative|positive} polarity clock enable.
@ -239,6 +249,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_SDFF_{C:N|P}{R:N|P}{V:0|1}_ (D, C, R, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {R:negative|positive} polarity synchronous {V:reset|set}.
//-
@ -263,6 +274,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_SDFFE_{C:N|P}{R:N|P}{V:0|1}{E:N|P}_ (D, C, R, E, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {R:negative|positive} polarity synchronous {V:reset|set} and {E:negative|positive}
//- polarity clock enable (with {V:reset|set} having priority).
@ -288,6 +300,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_SDFFCE_{C:N|P}{R:N|P}{V:0|1}{E:N|P}_ (D, C, R, E, Q)
//* group reg_ff
//-
//- A {C:negative|positive} edge D-type flip-flop with {R:negative|positive} polarity synchronous {V:reset|set} and {E:negative|positive}
//- polarity clock enable (with clock enable having priority).
@ -315,6 +328,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DLATCH_{E:N|P}_ (E, D, Q)
//* group reg_latch
//-
//- A {E:negative|positive} enable D-type latch.
//-
@ -336,6 +350,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DLATCH_{E:N|P}{R:N|P}{V:0|1}_ (E, R, D, Q)
//* group reg_latch
//-
//- A {E:negative|positive} enable D-type latch with {R:negative|positive} polarity {V:reset|set}.
//-
@ -360,6 +375,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $_DLATCHSR_{E:N|P}{S:N|P}{R:N|P}_ (E, S, R, D, Q)
//* group reg_latch
//-
//- A {E:negative|positive} enable D-type latch with {S:negative|positive} polarity set and {R:negative|positive}
//- polarity reset.

149
techlibs/common/simcells.v
View file

File diff suppressed because it is too large Load diff

221
techlibs/common/simlib.v
View file

@ -32,12 +32,10 @@
*/
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $not (A, Y)
//-
//- A bit-wise inverter. This corresponds to the Verilog unary prefix '~' operator.
//* ver 2
//* title Bit-wise inverter
//* group unary
//- This corresponds to the Verilog unary prefix '~' operator.
//-
module \$not (A, Y);
@ -63,6 +61,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $pos (A, Y)
//* group unary
//-
//- A buffer. This corresponds to the Verilog unary prefix '+' operator.
//-
@ -90,6 +89,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $buf (A, Y)
//* group unary
//-
//- A simple coarse-grain buffer cell type for the experimental buffered-normalized
//- mode. Note this cell does't get removed by 'opt_clean' and is not recommended
@ -111,6 +111,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $neg (A, Y)
//* group unary
//-
//- An arithmetic inverter. This corresponds to the Verilog unary prefix '-' operator.
//-
@ -138,6 +139,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $and (A, B, Y)
//* group binary
//-
//- A bit-wise AND. This corresponds to the Verilog '&' operator.
//-
@ -168,6 +170,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $or (A, B, Y)
//* group binary
//-
//- A bit-wise OR. This corresponds to the Verilog '|' operator.
//-
@ -198,6 +201,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $xor (A, B, Y)
//* group binary
//-
//- A bit-wise XOR. This corresponds to the Verilog '^' operator.
//-
@ -228,6 +232,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $xnor (A, B, Y)
//* group binary
//-
//- A bit-wise XNOR. This corresponds to the Verilog '~^' operator.
//-
@ -258,6 +263,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $reduce_and (A, Y)
//* group unary
//-
//- An AND reduction. This corresponds to the Verilog unary prefix '&' operator.
//-
@ -285,6 +291,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $reduce_or (A, Y)
//* group unary
//-
//- An OR reduction. This corresponds to the Verilog unary prefix '|' operator.
//-
@ -312,6 +319,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $reduce_xor (A, Y)
//* group unary
//-
//- A XOR reduction. This corresponds to the Verilog unary prefix '^' operator.
//-
@ -339,6 +347,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $reduce_xnor (A, Y)
//* group unary
//-
//- A XNOR reduction. This corresponds to the Verilog unary prefix '~^' operator.
//-
@ -366,6 +375,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $reduce_bool (A, Y)
//* group unary
//-
//- An OR reduction. This cell type is used instead of $reduce_or when a signal is
//- implicitly converted to a boolean signal, e.g. for operands of '&&' and '||'.
@ -394,6 +404,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $shl (A, B, Y)
//* group binary
//-
//- A logical shift-left operation. This corresponds to the Verilog '<<' operator.
//-
@ -424,6 +435,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $shr (A, B, Y)
//* group binary
//-
//- A logical shift-right operation. This corresponds to the Verilog '>>' operator.
//-
@ -454,6 +466,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $sshl (A, B, Y)
//* group binary
//-
//- An arithmatic shift-left operation.
//- This corresponds to the Verilog '<<<' operator.
@ -485,6 +498,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $sshr (A, B, Y)
//* group binary
//-
//- An arithmatic shift-right operation.
//- This corresponds to the Verilog '>>>' operator.
@ -512,7 +526,12 @@ endgenerate
endmodule
// --------------------------------------------------------
//* ver 2
//* title Variable shifter
//* group binary
//- Performs a right logical shift if the second operand is positive (or
//- unsigned), and a left logical shift if it is negative.
//-
module \$shift (A, B, Y);
parameter A_SIGNED = 0;
@ -544,7 +563,12 @@ endgenerate
endmodule
// --------------------------------------------------------
//* ver 2
//* title Indexed part-select
//* group binary
//* tags x-output
//- Same as the `$shift` cell, but fills with 'x'.
//-
module \$shiftx (A, B, Y);
parameter A_SIGNED = 0;
@ -569,7 +593,7 @@ endgenerate
endmodule
// --------------------------------------------------------
//* group arith
module \$fa (A, B, C, X, Y);
parameter WIDTH = 1;
@ -585,6 +609,7 @@ assign Y = t1 ^ C, X = (t2 | t3) ^ (Y ^ Y);
endmodule
// --------------------------------------------------------
//* group arith
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
@ -620,17 +645,14 @@ end
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $alu (A, B, CI, BI, X, Y, CO)
//-
//- Arithmetic logic unit.
//* ver 2
//* title Arithmetic logic unit
//* group arith
//- A building block supporting both binary addition/subtraction operations, and
//- indirectly, comparison operations.
//- Typically created by the `alumacc` pass, which transforms:
//- $add, $sub, $lt, $le, $ge, $gt, $eq, $eqx, $ne, $nex
//- cells into this $alu cell.
//- `$add`, `$sub`, `$lt`, `$le`, `$ge`, `$gt`, `$eq`, `$eqx`, `$ne`, `$nex`
//- cells into this `$alu` cell.
//-
module \$alu (A, B, CI, BI, X, Y, CO);
@ -688,6 +710,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $lt (A, B, Y)
//* group binary
//-
//- A less-than comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '<' operator.
@ -719,6 +742,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $le (A, B, Y)
//* group binary
//-
//- A less-than-or-equal-to comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '<=' operator.
@ -750,6 +774,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $eq (A, B, Y)
//* group binary
//-
//- An equality comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '==' operator.
@ -781,6 +806,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $ne (A, B, Y)
//* group binary
//-
//- An inequality comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '!=' operator.
@ -808,15 +834,15 @@ endgenerate
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $eqx (A, B, Y)
//-
//- An exact equality comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '===' operator.
//- Unlike equality comparison that can give 'x' as output,
//- an exact equality comparison will strictly give '0' or '1' as output.
//* ver 2
//* title Case equality
//* group binary
//* tags x-aware
//- An exact equality comparison between inputs 'A' and 'B'. Also known as the
//- case equality operator. This corresponds to the Verilog '===' operator.
//- Unlike equality comparison that can give 'x' as output, an exact equality
//- comparison will strictly give '0' or '1' as output, even if input includes
//- 'x' or 'z' values.
//-
module \$eqx (A, B, Y);
@ -841,15 +867,13 @@ endgenerate
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $nex (A, B, Y)
//-
//- An exact inequality comparison between inputs 'A' and 'B'.
//* ver 2
//* title Case inequality
//* group binary
//* tags x-aware
//- This corresponds to the Verilog '!==' operator.
//- Unlike inequality comparison that can give 'x' as output,
//- an exact inequality comparison will strictly give '0' or '1' as output.
//-
//- Refer to `$eqx` for more details.
//-
module \$nex (A, B, Y);
@ -878,6 +902,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $ge (A, B, Y)
//* group binary
//-
//- A greater-than-or-equal-to comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '>=' operator.
@ -909,6 +934,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $gt (A, B, Y)
//* group binary
//-
//- A greater-than comparison between inputs 'A' and 'B'.
//- This corresponds to the Verilog '>' operator.
@ -940,6 +966,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $add (A, B, Y)
//* group binary
//-
//- Addition of inputs 'A' and 'B'. This corresponds to the Verilog '+' operator.
//-
@ -970,6 +997,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $sub (A, B, Y)
//* group binary
//-
//- Subtraction between inputs 'A' and 'B'.
//- This corresponds to the Verilog '-' operator.
@ -1001,6 +1029,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $mul (A, B, Y)
//* group binary
//-
//- Multiplication of inputs 'A' and 'B'.
//- This corresponds to the Verilog '*' operator.
@ -1031,6 +1060,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $macc (A, B, Y)
//* group arith
//-
//- Multiply and accumulate.
//- A building block for summing any number of negated and unnegated signals
@ -1178,12 +1208,12 @@ end
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $div (A, B, Y)
//-
//- Division with truncated result (rounded towards 0).
//* ver 2
//* title Divider
//* group binary
//* tags x-output
//- This corresponds to the Verilog '/' operator, performing division and
//- truncating the result (rounding towards 0).
//-
module \$div (A, B, Y);
@ -1208,12 +1238,12 @@ endgenerate
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $mod (A, B, Y)
//-
//- Modulo/remainder of division with truncated result (rounded towards 0).
//* ver 2
//* title Modulo
//* group binary
//* tags x-output
//- This corresponds to the Verilog '%' operator, giving the module (or
//- remainder) of division and truncating the result (rounding towards 0).
//-
//- Invariant: $div(A, B) * B + $mod(A, B) == A
//-
@ -1244,6 +1274,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $divfloor (A, B, Y)
//* group binary
//-
//- Division with floored result (rounded towards negative infinity).
//-
@ -1281,6 +1312,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $modfloor (A, B, Y)
//* group binary
//-
//- Modulo/remainder of division with floored result (rounded towards negative infinity).
//-
@ -1321,6 +1353,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $pow (A, B, Y)
//* group binary
//-
//- Exponentiation of an input (Y = A ** B).
//- This corresponds to the Verilog '**' operator.
@ -1359,6 +1392,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $logic_not (A, Y)
//* group unary
//-
//- A logical inverter. This corresponds to the Verilog unary prefix '!' operator.
//-
@ -1386,6 +1420,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $logic_and (A, B, Y)
//* group binary
//-
//- A logical AND. This corresponds to the Verilog '&&' operator.
//-
@ -1416,6 +1451,7 @@ endmodule
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $logic_or (A, B, Y)
//* group binary
//-
//- A logical OR. This corresponds to the Verilog '||' operator.
//-
@ -1442,7 +1478,7 @@ endgenerate
endmodule
// --------------------------------------------------------
//* group wire
module \$slice (A, Y);
parameter OFFSET = 0;
@ -1457,10 +1493,10 @@ assign Y = A >> OFFSET;
endmodule
// --------------------------------------------------------
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
//- $concat (A, B, Y)
//* group wire
//-
//- Concatenation of inputs into a single output ( Y = {B, A} ).
//-
@ -1478,6 +1514,7 @@ assign Y = {B, A};
endmodule
// --------------------------------------------------------
//* group mux
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
@ -1498,7 +1535,12 @@ assign Y = S ? B : A;
endmodule
// --------------------------------------------------------
//* ver 2
//* title Binary-encoded multiplexer
//* group mux
//- Selects between 'slices' of A where each value of S corresponds to a unique
//- slice.
//-
module \$bmux (A, S, Y);
parameter WIDTH = 0;
@ -1525,7 +1567,13 @@ endgenerate
endmodule
// --------------------------------------------------------
//* ver 2
//* title Priority-encoded multiplexer
//* group mux
//* tags x-output
//- Selects between 'slices' of B where each slice corresponds to a single bit
//- of S. Outputs A when all bits of S are low.
//-
module \$pmux (A, B, S, Y);
parameter WIDTH = 0;
@ -1559,6 +1607,7 @@ end
endmodule
// --------------------------------------------------------
//* group mux
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
@ -1587,6 +1636,7 @@ endmodule
// --------------------------------------------------------
`ifndef SIMLIB_NOLUT
//* group logic
module \$lut (A, Y);
@ -1602,6 +1652,7 @@ endmodule
`endif
// --------------------------------------------------------
//* group logic
module \$sop (A, Y);
@ -1630,6 +1681,7 @@ end
endmodule
// --------------------------------------------------------
//* group mux
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
//-
@ -1652,6 +1704,7 @@ assign Y = EN ? A : 'bz;
endmodule
// --------------------------------------------------------
//* group spec
module \$specify2 (EN, SRC, DST);
@ -1690,6 +1743,7 @@ endspecify
endmodule
// --------------------------------------------------------
//* group spec
module \$specify3 (EN, SRC, DST, DAT);
@ -1798,6 +1852,7 @@ endspecify
endmodule
// --------------------------------------------------------
//* group spec
module \$specrule (EN_SRC, EN_DST, SRC, DST);
@ -1827,7 +1882,12 @@ endspecify
endmodule
// --------------------------------------------------------
//* ver 2
//* title Bit-wise case equality
//* group binary
//* tags x-aware
//- A bit-wise version of `$eqx`.
//-
module \$bweqx (A, B, Y);
parameter WIDTH = 0;
@ -1845,7 +1905,11 @@ endgenerate
endmodule
// --------------------------------------------------------
//* ver 2
//* title Bit-wise multiplexer
//* group mux
//- Equivalent to a series of 1-bit wide `$mux` cells.
//-
module \$bwmux (A, B, S, Y);
parameter WIDTH = 0;
@ -1864,6 +1928,7 @@ endgenerate
endmodule
// --------------------------------------------------------
//* group formal
module \$assert (A, EN);
@ -1881,6 +1946,7 @@ end
endmodule
// --------------------------------------------------------
//* group formal
module \$assume (A, EN);
@ -1898,6 +1964,7 @@ end
endmodule
// --------------------------------------------------------
//* group formal
module \$live (A, EN);
@ -1906,6 +1973,7 @@ input A, EN;
endmodule
// --------------------------------------------------------
//* group formal
module \$fair (A, EN);
@ -1914,6 +1982,7 @@ input A, EN;
endmodule
// --------------------------------------------------------
//* group formal
module \$cover (A, EN);
@ -1922,6 +1991,7 @@ input A, EN;
endmodule
// --------------------------------------------------------
//* group formal
module \$initstate (Y);
@ -1939,6 +2009,7 @@ end
endmodule
// --------------------------------------------------------
//* group formal
module \$anyconst (Y);
@ -1951,6 +2022,7 @@ assign Y = 'bx;
endmodule
// --------------------------------------------------------
//* group formal
module \$anyseq (Y);
@ -1967,6 +2039,7 @@ endmodule
`ifndef SIMLIB_GLOBAL_CLOCK
`define SIMLIB_GLOBAL_CLOCK $global_clk
`endif
//* group formal
module \$anyinit (D, Q);
parameter WIDTH = 0;
@ -1983,6 +2056,7 @@ end
endmodule
`endif
// --------------------------------------------------------
//* group formal
module \$allconst (Y);
@ -1995,6 +2069,7 @@ assign Y = 'bx;
endmodule
// --------------------------------------------------------
//* group formal
module \$allseq (Y);
@ -2007,6 +2082,7 @@ assign Y = 'bx;
endmodule
// --------------------------------------------------------
//* group formal
module \$equiv (A, B, Y);
@ -2027,6 +2103,7 @@ end
endmodule
// --------------------------------------------------------
//* group debug
module \$print (EN, TRG, ARGS);
@ -2046,6 +2123,7 @@ input [ARGS_WIDTH-1:0] ARGS;
endmodule
// --------------------------------------------------------
//* group debug
module \$check (A, EN, TRG, ARGS);
@ -2068,6 +2146,7 @@ endmodule
// --------------------------------------------------------
`ifndef SIMLIB_NOSR
//* group reg
module \$sr (SET, CLR, Q);
@ -2100,6 +2179,7 @@ endmodule
`ifndef SIMLIB_GLOBAL_CLOCK
`define SIMLIB_GLOBAL_CLOCK $global_clk
`endif
//* group formal
module \$ff (D, Q);
@ -2116,6 +2196,7 @@ endmodule
`endif
// --------------------------------------------------------
//* group reg
module \$dff (CLK, D, Q);
@ -2134,6 +2215,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$dffe (CLK, EN, D, Q);
@ -2154,6 +2236,7 @@ endmodule
// --------------------------------------------------------
`ifndef SIMLIB_NOSR
//* group reg
module \$dffsr (CLK, SET, CLR, D, Q);
@ -2186,6 +2269,7 @@ endgenerate
endmodule
// --------------------------------------------------------
//* group reg
module \$dffsre (CLK, SET, CLR, EN, D, Q);
@ -2220,6 +2304,7 @@ endmodule
`endif
// --------------------------------------------------------
//* group reg
module \$adff (CLK, ARST, D, Q);
@ -2244,6 +2329,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$aldff (CLK, ALOAD, AD, D, Q);
@ -2268,6 +2354,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$sdff (CLK, SRST, D, Q);
@ -2292,6 +2379,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$adffe (CLK, ARST, EN, D, Q);
@ -2317,6 +2405,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$aldffe (CLK, ALOAD, AD, EN, D, Q);
@ -2342,6 +2431,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$sdffe (CLK, SRST, EN, D, Q);
@ -2367,6 +2457,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$sdffce (CLK, SRST, EN, D, Q);
@ -2394,6 +2485,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$dlatch (EN, D, Q);
@ -2412,6 +2504,7 @@ end
endmodule
// --------------------------------------------------------
//* group reg
module \$adlatch (EN, ARST, D, Q);
@ -2435,6 +2528,7 @@ endmodule
// --------------------------------------------------------
`ifndef SIMLIB_NOSR
//* group reg
module \$dlatchsr (EN, SET, CLR, D, Q);
@ -2468,6 +2562,7 @@ endmodule
`endif
// --------------------------------------------------------
//* group fsm
module \$fsm (CLK, ARST, CTRL_IN, CTRL_OUT);
@ -2562,6 +2657,7 @@ endmodule
// --------------------------------------------------------
`ifndef SIMLIB_NOMEM
//* group mem
module \$memrd (CLK, EN, ADDR, DATA);
@ -2586,6 +2682,8 @@ end
endmodule
//* group mem
module \$memrd_v2 (CLK, EN, ARST, SRST, ADDR, DATA);
parameter MEMID = "";
@ -2615,6 +2713,7 @@ end
endmodule
// --------------------------------------------------------
//* group mem
module \$memwr (CLK, EN, ADDR, DATA);
@ -2640,6 +2739,7 @@ end
endmodule
//* group mem
module \$memwr_v2 (CLK, EN, ADDR, DATA);
parameter MEMID = "";
@ -2666,6 +2766,7 @@ end
endmodule
// --------------------------------------------------------
//* group mem
module \$meminit (ADDR, DATA);
@ -2689,6 +2790,7 @@ end
endmodule
// --------------------------------------------------------
//* group mem
module \$meminit_v2 (ADDR, DATA, EN);
@ -2713,6 +2815,7 @@ end
endmodule
// --------------------------------------------------------
//* group mem
module \$mem (RD_CLK, RD_EN, RD_ADDR, RD_DATA, WR_CLK, WR_EN, WR_ADDR, WR_DATA);
@ -2801,6 +2904,8 @@ end
endmodule
//* group mem
module \$mem_v2 (RD_CLK, RD_EN, RD_ARST, RD_SRST, RD_ADDR, RD_DATA, WR_CLK, WR_EN, WR_ADDR, WR_DATA);
parameter MEMID = "";
@ -2920,7 +3025,7 @@ endmodule
`endif
// --------------------------------------------------------
//* group formal_tag
module \$set_tag (A, SET, CLR, Y);
parameter TAG = "";
@ -2936,7 +3041,7 @@ assign Y = A;
endmodule
// --------------------------------------------------------
//* group formal_tag
module \$get_tag (A, Y);
parameter TAG = "";
@ -2950,7 +3055,7 @@ assign Y = A;
endmodule
// --------------------------------------------------------
//* group formal_tag
module \$overwrite_tag (A, SET, CLR);
parameter TAG = "";
@ -2963,7 +3068,7 @@ input [WIDTH-1:0] CLR;
endmodule
// --------------------------------------------------------
//* group formal_tag
module \$original_tag (A, Y);
parameter TAG = "";
@ -2977,7 +3082,7 @@ assign Y = A;
endmodule
// --------------------------------------------------------
//* group formal_tag
module \$future_ff (A, Y);
parameter WIDTH = 0;
@ -2990,7 +3095,7 @@ assign Y = A;
endmodule
// --------------------------------------------------------
//* group debug
(* noblackbox *)
module \$scopeinfo ();