mirror of
https://github.com/YosysHQ/yosys
synced 2025-11-23 06:01:27 +00:00
966f52e123
Also moved them to the bottom, instead of being under the "command help" heading. Now includes more info about cells, and the custom sphinx domains/directives/roles we have.
504 lines
19 KiB
ReStructuredText
504 lines
19 KiB
ReStructuredText
Generated help messages and documentation
|
|
=========================================
|
|
|
|
All Yosys commands and built-in cell types should include help text, documenting
|
|
their functionality for users. This help text is made available through the
|
|
`help` command, and online via `ReadtheDocs`_ as part of the :doc:`/cmd_ref` and
|
|
:doc:`/cell_index` documentation. When running locally, any commands provided
|
|
by loaded plugins (either from the command line when calling ``yosys``, or
|
|
dynamically with the `plugin` command) will also be available to the `help`
|
|
command.
|
|
|
|
.. _ReadtheDocs: https://about.readthedocs.com/
|
|
|
|
.. note::
|
|
|
|
Since help text for commands is generated from compiled code, the online help
|
|
may differ from that produced by `help`. Some commands, like `abc`, may be
|
|
completely unavailable depending on compile flags; while others may limit
|
|
specific features, such as whether the `synth` script pass uses ABC.
|
|
|
|
Command help
|
|
------------
|
|
|
|
The first stop for command help text is the ``Pass::short_help``. This is a
|
|
short sentence describing the pass, and is set in the ``Pass`` constructor with
|
|
the name of the pass, as demonstrated here with `chformal`.
|
|
|
|
.. literalinclude:: /generated/chformal.cc
|
|
:language: c++
|
|
:start-at: public Pass {
|
|
:end-at: ChformalPass()
|
|
:caption: ``ChformalPass()`` from :file:`passes/cmds/chformal.cc`
|
|
:append:
|
|
// ...
|
|
} ChformalPass;
|
|
|
|
All currently available commands are listed with their ``short_help`` string
|
|
when calling `help` without arguments, and is more or less the same as the
|
|
unlisted :ref:`command index <commandindex>`. The string is also used when
|
|
hovering over links to commands in the documentation, and in section headings
|
|
like :ref:`chformal autocmd`.
|
|
|
|
The next section shows the complete help text for the `chformal` command. This
|
|
can be displayed locally by using ``help <command>`` (or ``yosys -h <command>``
|
|
from the command line). The general format is to show each usage signature (how
|
|
the command is called), followed by a paragraph describing what the pass does,
|
|
and a list of options or flags available. Additional arguments in the signature
|
|
or option may use square brackets (``[]``) to indicate optional parts, and angle
|
|
brackets (``<>``) for required parts. The pipe character ``|`` may be used to
|
|
indicate mutually exclusive arguments.
|
|
|
|
.. note::
|
|
|
|
Remember that when using ``Frontend`` and ``Backend`` the pass name will be
|
|
be prefixed with ``read_`` or ``write_`` respectively. Usage signatures must
|
|
match the pass name available in commands/scripts, which is available as
|
|
``Pass::pass_name``.
|
|
|
|
.. todo:: decide on a formatting style for pass options
|
|
|
|
.. _chformal autocmd:
|
|
|
|
.. autocmd:: chformal
|
|
:noindex:
|
|
|
|
The ``Pass::help()`` method
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This is the original way to provide help text, and as of this writing is still
|
|
the most common. The ``log()`` function should be called directly to print and
|
|
format the help text, and each line should be limited to 80 (printed)
|
|
characters. While it is possible to provide arbitrary formatting, it is
|
|
preferred to follow the guidelines here to maintain consistency with other
|
|
passes and to assist in correct parsing and formatting during RST generation
|
|
(i.e. these docs).
|
|
|
|
The first line should always be a blank line, followed by the primary usage
|
|
signature for the command. Each usage signature should be indented with 4
|
|
spaces, and followed by a blank line. Each option or flag should start on a new
|
|
line indented with 4 spaces, followed by a description of the option which is
|
|
indented by a further 4 spaces, and then a blank line. Option descriptions
|
|
typically start with lower case, and may forgo a trailing period (``.``). Where
|
|
multiple options share a description the blank line between options should be
|
|
omitted.
|
|
|
|
.. note::
|
|
|
|
`Dumping to json`_ has more on how formatting in ``help()`` gets parsed.
|
|
|
|
|
|
The ``Pass::formatted_help()`` method
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The ``formatted_help`` method serves two purposes in help generation, both of
|
|
which are optional. In both cases, any pass which uses the method should
|
|
``#include "kernel/log_help.h"``, and begin the method by calling ``auto *help =
|
|
PrettyHelp::get_current();``. The method finishes by returning a boolean value.
|
|
``true`` means help content has been added to the current ``PrettyHelp``, while
|
|
``false`` indicates that ``Pass::help()`` should be called instead.
|
|
|
|
Setting a command group
|
|
^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
Command groups are used when `Dumping to json`_, so that related
|
|
commands can be presented together in documentation. For example, all of the
|
|
formal commands (which `chformal` is one of) are listed under
|
|
:doc:`/cmd/index_formal`, by using the ``autocmdgroup`` directive in
|
|
:file:`docs/source/cmd/index_formal.rst`. By default, commands are grouped by
|
|
their source location, such that the group is the same as the path to the source
|
|
file.
|
|
|
|
.. note::
|
|
|
|
Source location tracking requires :makevar:`ENABLE_HELP_SOURCE` to be set in
|
|
the makefile. Some passes, like the ``opt_*`` family, are able to be grouped
|
|
by the name of the pass; but most will be assigned the ``unknown`` group.
|
|
|
|
For frontends and backends, source code is structured such that different
|
|
formats are located in different folders. Default behavior is to instead
|
|
group all of these passes as :doc:`/cmd/index_frontends` and
|
|
:doc:`/cmd/index_backends` respectively. Without location tracking, the
|
|
fallback is to look for passes that start with ``read_`` or ``write_``.
|
|
|
|
It is possible to set the group of a command explicitly with the
|
|
``PrettyHelp::set_group()`` method. This allows grouping of commands which may
|
|
not share a common source location, as well as ensuring that commands are still
|
|
grouped when location tracking is disabled. Because ``Pass::formatted_help()``
|
|
returns if it produced help content, it is completely valid to override the
|
|
method, get the current instance of ``PrettyHelp``, set the command group, and
|
|
then return ``false``.
|
|
|
|
.. warning::
|
|
|
|
There is currently no warning available for groups that do not have a
|
|
corresponding ``autocmdgroup``. If you add a new command group, make sure
|
|
that it has a corresponding index page.
|
|
|
|
|
|
Rich help text
|
|
^^^^^^^^^^^^^^
|
|
|
|
The second purpose of ``Pass::formatted_help`` is to provide richer help
|
|
content which is able to take advantage of the reStructuredText formatting used
|
|
here in the web docs. It also provides a more fluid way of writing help text,
|
|
without getting caught up in the terminal-first spacing requirements of writing
|
|
for ``Pass::help()``.
|
|
|
|
Help content is a list of ``ContentListing`` nodes on a root node, which can be
|
|
found by calling ``PrettyHelp::get_root()``. Each node has a type, a body, and
|
|
its own list of children ``ContentListing``\ s. Adding content is done with the
|
|
``ContentListing::{usage, option, codeblock, paragraph}`` methods, which each
|
|
add a new child node with a type set to the calling method. Let's take a look
|
|
at the source code for `chformal`.
|
|
|
|
.. literalinclude:: /generated/chformal.cc
|
|
:language: c++
|
|
:start-at: bool formatted_help()
|
|
:end-before: void execute
|
|
:caption: ``ChformalPass::formatted_help()`` from :file:`passes/cmds/chformal.cc`
|
|
|
|
We can see that each of the ``ContentListing`` methods have the body of the new
|
|
node as the first argument. For a ``usage`` node, this is how to call the
|
|
command (i.e. its usage signature). ``paragraph`` nodes contain a paragraph of
|
|
text with line breaks added automatically; the argument itself should contain
|
|
any line breaks, but the string can be broken across multiple lines as shown.
|
|
The body of a ``paragraph`` node is treated as raw RST, allowing for inline
|
|
formatting and references as if it were written in the RST file itself. As
|
|
shown in the example (and the :ref:`formatted output above <chformal autocmd>`),
|
|
this includes using single backticks for linking to cells or commands, and
|
|
double backticks for raw code.
|
|
|
|
The ``option`` method lists a single option for the command, usually starting
|
|
with a dash (``-``). An optional second argument can be provided with adds a
|
|
paragraph node as a child of the option, and is used for describing the option.
|
|
Where multiple options share a description, it should be added to the last
|
|
option.
|
|
|
|
.. note::
|
|
|
|
To add multiple paragraphs to an option's description,
|
|
``ContentListing::open_option()`` should be used instead. This method
|
|
returns the option node, which can then be used to call
|
|
``ContentList::paragraph()`` multiple times.
|
|
|
|
``codeblock`` content is displayed verbatim, and content should include line
|
|
breaks as desired. No extra formatting will be applied to the text, and it will
|
|
be rendered with a monospace font; making it perfect for code sections or ASCII
|
|
art diagrams which render the same on the web as they do in the terminal. An
|
|
optional second argument is available for specifying the language in RST output
|
|
for code syntax highlighting (use ``yoscrypt`` for yosys script syntax
|
|
highlighting).
|
|
|
|
..
|
|
not recommended since it (currently) doesn't render in the terminal
|
|
|
|
The final method available is ``ContentListing::open_usage``. As with
|
|
``open_option`` creates and returns a new node which can have additional content
|
|
added to it directly. For the usage node, this can be used for example to add
|
|
text/options specific to a given usage of the command. In the web documentation
|
|
any content added in this way will be indented under the usage signature.
|
|
|
|
|
|
Command line rendering
|
|
~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
- if ``Pass::formatted_help()`` returns true, will call
|
|
``PrettyHelp::log_help()``
|
|
|
|
+ traverse over the children of the root node and render as plain text
|
|
+ effectively the reverse of converting unformatted ``Pass::help()`` text
|
|
+ lines are broken at 80 characters while maintaining indentation (controlled
|
|
by ``MAX_LINE_LEN`` in :file:`kernel/log_help.cc`)
|
|
+ each line is broken into words separated by spaces, if a given word starts
|
|
and ends with backticks they will be stripped
|
|
|
|
- if it returns false it will call ``Pass::help()`` which should call ``log()``
|
|
directly to print and format help text
|
|
|
|
+ if ``Pass::help()`` is not overridden then a default message about missing
|
|
help will be displayed
|
|
|
|
.. literalinclude:: /generated/chformal.log
|
|
:lines: 2-
|
|
|
|
|
|
Cell help
|
|
---------
|
|
|
|
- :file:`techlibs/common/simcells.v` and :file:`techlibs/common/simlib.v`
|
|
- parsed by :file:`techlibs/common/cellhelp.py`
|
|
|
|
+ unlike commands, cell help text is generated at compile time
|
|
+ only formatting occurs at run time
|
|
+ no support for custom cells in plugins
|
|
|
|
- comments preceding cell type converted to a ``SimHelper`` struct, defined in
|
|
:file:`kernel/register.cc`
|
|
- ``#include``\ d in :file:`kernel/register.cc`, creating a map of cell types to
|
|
their ``SimHelper`` struct.
|
|
|
|
- ``help -cells``
|
|
|
|
- lists all cells with their input/output ports
|
|
- again an unlisted :ref:`cell index <cellindex>`
|
|
|
|
- ``help <celltype>``
|
|
|
|
- prints help message for ``<celltype>``
|
|
- constructed from ``SimHelper`` content depending on version
|
|
|
|
- ``help <celltype>+``
|
|
|
|
- prints verilog code for ``<celltype>``
|
|
|
|
v1 (default)
|
|
~~~~~~~~~~~~
|
|
|
|
- Legacy format
|
|
- Expects formatting as follows:
|
|
|
|
.. code-block:: verilog
|
|
|
|
//-
|
|
//- $<celltype> (<ports>)
|
|
//* group <cellgroup>
|
|
//-
|
|
//- <cell description>
|
|
//-
|
|
module \$<celltype> (<ports>);
|
|
// ...
|
|
endmodule
|
|
|
|
- ``//* group`` line is generally after the cell signature, but can appear
|
|
anywhere in the comment block
|
|
|
|
- determines where the cell is included in sphinx
|
|
- check :file:`docs/source/cell` for current groups
|
|
- a missing group will raise an error
|
|
- assigning an unused group will result in the cell not being included in the
|
|
sphinx docs
|
|
|
|
- the port signature line (``//- $<celltype> (<ports>)``) must start with (at
|
|
least) 4 spaces (not tabs)
|
|
|
|
- the empty lines (``//-``) before/after the signature are required
|
|
|
|
- cell description can be multiple lines, but each line must start with ``//-``
|
|
and a space
|
|
|
|
- description should have a trailing empty line
|
|
- line breaks are preserved in `help` calls but will be rendered as text in
|
|
sphinx docs, with empty lines being required between paragraphs
|
|
|
|
- cells in :file:`techlibs/common/simcells.v` can have optional truth table at
|
|
the end of the cell description which is rendered in sphinx docs as a literal
|
|
code block
|
|
- e.g. `$_NOT_`:
|
|
|
|
.. code-block:: verilog
|
|
|
|
//-
|
|
//- $_NOT_ (A, Y)
|
|
//* group comb_simple
|
|
//-
|
|
//- An inverter gate.
|
|
//-
|
|
//- Truth table: A | Y
|
|
//- ---+---
|
|
//- 0 | 1
|
|
//- 1 | 0
|
|
//-
|
|
|
|
v2 (more expressive)
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
- each field of the ``SimHelper`` struct can be assigned with:
|
|
|
|
.. code-block:: verilog
|
|
|
|
//* <name> <value>
|
|
|
|
- ``ver`` must be explicitly set as ``2``
|
|
- optional fields ``title`` and ``tags``
|
|
|
|
- title used for better displaying of cell
|
|
- tags is a space-separated list of :doc:`/cell/properties`
|
|
|
|
- the port signature is automatically generated from the ``module`` definition
|
|
- cell description is the same as v1
|
|
- can link to commands or passes using backticks (`````)
|
|
- e.g. `$nex`:
|
|
|
|
.. code-block:: verilog
|
|
|
|
//* ver 2
|
|
//* title Case inequality
|
|
//* group binary
|
|
//* tags x-aware
|
|
//- This corresponds to the Verilog '!==' operator.
|
|
//-
|
|
//- Refer to `$eqx` for more details.
|
|
//-
|
|
|
|
- code blocks can be included as following:
|
|
|
|
.. code-block:: verilog
|
|
|
|
//- text
|
|
//- ::
|
|
//-
|
|
//- monospaced text
|
|
//-
|
|
//- indentation and line length will be preserved, giving a scroll bar if necessary for the browser window
|
|
//-
|
|
//- more text
|
|
|
|
- the empty line after the ``::`` and before the text continues are required
|
|
- the ``::`` line will be ignored in the `help` call while sphinx docs will
|
|
treat everything that follows as a literal block until the next unindented
|
|
line:
|
|
|
|
text
|
|
::
|
|
|
|
monospaced text
|
|
|
|
indentation and line length will be preserved, giving a scroll bar if necessary for the browser window
|
|
|
|
more text
|
|
|
|
|
|
Dumping to json
|
|
---------------
|
|
|
|
- `help -dump-cmds-json cmds.json`
|
|
|
|
+ generates a ``ContentListing`` for each command registered in Yosys
|
|
+ tries to parse unformatted ``Pass::help()`` output if
|
|
``Pass::formatted_help()`` is unimplemented or returns false
|
|
|
|
* if a line starts with four spaces followed by the name of the command then
|
|
a space, it is parsed as a signature (usage node)
|
|
* if a line is indented and starts with a dash (``-``), it is parsed as an
|
|
option
|
|
* anything else is parsed as a codeblock and added to either the root node
|
|
or the current option depending on the indentation
|
|
|
|
+ dictionary of command name to ``ContentListing``
|
|
|
|
* uses ``ContentListing::to_json()`` recursively for each node in root
|
|
* root node used for source location of class definition
|
|
* includes flags set during pass constructor (e.g. ``experimental_flag`` set
|
|
by ``Pass::experimental()``)
|
|
* also title (``short_help`` argument in ``Pass::Pass``), group, and class
|
|
name
|
|
|
|
+ dictionary of group name to list of commands in that group
|
|
|
|
- used by sphinx autodoc to generate help content
|
|
|
|
.. literalinclude:: /generated/cmds.json
|
|
:language: json
|
|
:start-at: "chformal": {
|
|
:end-before: "chparam": {
|
|
:caption: `chformal` in generated :file:`cmds.json`
|
|
|
|
.. note:: Synthesis command scripts are special cased
|
|
|
|
If the final block of help output starts with the string ``"The following
|
|
commands are executed by this synthesis command:\n"``, then the rest of the
|
|
code block is formatted as ``yoscrypt`` (e.g. `synth_ice40`). The caveat
|
|
here is that if the ``script()`` calls ``run()`` on any commands *prior* to
|
|
the first ``check_label`` then the auto detection will break and revert to
|
|
unformatted code (e.g. `synth_fabulous`).
|
|
|
|
|
|
Cells and commands in Sphinx
|
|
----------------------------
|
|
|
|
To support the rich documentation of commands and cells in Yosys, we use two
|
|
custom `Sphinx Domains`_.
|
|
|
|
.. _Sphinx Domains: https://www.sphinx-doc.org/en/master/usage/domains/index.html
|
|
|
|
- ``yoscrypt`` role allows inline code to have yosys script syntax highlighting
|
|
- default role of ``autoref``
|
|
|
|
+ any text in single backticks without an explicit role will be assigned this one
|
|
+ will convert to ``cell:ref`` if it begins with ``$``, otherwise ``cmd:ref``
|
|
+ to attempt linking there must be no spaces, and it must not begin with a
|
|
dash (``-``)
|
|
+ ```chformal``` (or ``:autoref:`chformal```) -> ``:cmd:ref:`chformal``` -> `chformal`
|
|
+ also works with two words, if the first one is ``help``
|
|
+ ```help $add``` -> ``:cell:ref:`help $add <$add>``` -> `help $add`
|
|
+ fallback to formatting as inline yoscrypt
|
|
+ ```-remove``` -> `-remove`
|
|
+ ```chformal -remove``` -> ``:yoscrypt:`chformal -remove``` -> `chformal -remove`
|
|
|
|
Using autodoc
|
|
~~~~~~~~~~~~~
|
|
|
|
- below is the raw RST output from ``autocmd`` (``YosysCmdDocumenter`` class in
|
|
:file:`docs/util/cmd_documenter.py`) for `chformal` command
|
|
- heading will be rendered as a subheading of the most recent heading (see
|
|
`chformal autocmd`_ above rendered under `Command help`_)
|
|
- ``.. cmd:def:: <cmd>`` line is indexed for cross references with ``:cmd:ref:``
|
|
directive (`chformal autocmd`_ above uses ``:noindex:`` option so that
|
|
`chformal` still links to the correct location)
|
|
|
|
+ ``:title:`` option controls text that appears when hovering over the
|
|
`chformal` link
|
|
|
|
- commands with warning flags (experimental or internal) add a ``.. warning``
|
|
block before any of the help content
|
|
- if a command has no ``source_location`` the ``.. note`` at the bottom will
|
|
instead link to :doc:`/cmd/index_other`
|
|
|
|
.. _showing autocmd generated rst:
|
|
|
|
.. autocmd_rst:: chformal
|
|
|
|
- command groups documented with ``autocmdgroup <group>``
|
|
|
|
+ with ``:members:`` option this is the same as calling ``autocmd`` for each
|
|
member of the group
|
|
|
|
- ``autocell`` and ``autocellgroup``
|
|
|
|
+ very similar to ``autocmd`` and ``autocmdgroup`` but for cells instead of
|
|
commands (``YosysCellDocumenter`` in :file:`docs/util/cell_documenter.py`)
|
|
+ optionally includes verilog source for cell(s) with ``:source:`` option
|
|
(plus ``:linenos:``)
|
|
+ cell definitions do not include titles
|
|
+ cells can have properties (:ref:`propindex`)
|
|
|
|
- bonus ``autocmd_rst``, used exclusively on this page for `showing autocmd
|
|
generated rst`_
|
|
|
|
Our custom Sphinx domains
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
- ``cmd`` and ``cell``
|
|
- Directives
|
|
|
|
+ ``cmd:def`` provide command definition
|
|
+ ``cmd:usage`` used by ``autocmd`` for command usage signatures
|
|
+ ``cell:def`` provide cell definition
|
|
+ ``cell:defprop`` provide cell property definition (used in
|
|
:doc:`/cell/properties`)
|
|
+ ``cell:source`` used by ``autocell`` for simulation models
|
|
|
|
- Roles
|
|
|
|
+ ``cmd:ref`` link to a ``cmd:def`` with the same name
|
|
+ ``cmd:title`` same as ``cmd:ref``, but includes the short help in the text
|
|
|
|
- ``:cmd:title:`chformal``` -> :cmd:title:`chformal`
|
|
|
|
+ ``cell:ref`` link to a ``cell:def`` with the same name
|
|
+ ``cell:title``
|
|
|
|
- ``:cell:title:`$nex``` -> :cell:title:`$nex`
|
|
|
|
+ ``cell:prop`` link to a ``cell:defprop`` of the same name
|