mirrors/yosys
3
0
Fork 0
mirror of https://github.com/YosysHQ/yosys synced 2025-06-23 22:33:41 +00:00
Code Activity

cxxrtl: expose driver kind in debug information.

Browse source 
This can be useful to determine whether the wire should be a part of
a design checkpoint, whether it can be used to override design state,
and whether driving it may cause a conflict.
This commit is contained in:
whitequark 2020-09-02 17:16:10 +00:00
parent c7b2f07edf
commit 691418e13a
3 changed files with 112 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

45
backends/cxxrtl/cxxrtl_capi.h
View file

@ -73,6 +73,10 @@ int cxxrtl_commit(cxxrtl_handle handle);
size_t cxxrtl_step(cxxrtl_handle handle);
// Type of a simulated object.
//
// The type of a simulated object indicates the way it is stored and the operations that are legal
// to perform on it (i.e. won't crash the simulation). It says very little about object semantics,
// which is specified through flags.
enum cxxrtl_type {
// Values correspond to singly buffered netlist nodes, i.e. nodes driven exclusively by
// combinatorial cells, or toplevel input nodes.
@ -86,7 +90,8 @@ enum cxxrtl_type {
CXXRTL_VALUE = 0,
// Wires correspond to doubly buffered netlist nodes, i.e. nodes driven, at least in part, by
// storage cells, or by combinatorial cells that are a part of a feedback path.
// storage cells, or by combinatorial cells that are a part of a feedback path. They are also
// present in non-optimized builds.
//
// Wires can be inspected via the `curr` pointer and modified via the `next` pointer (which are
// distinct for wires). Note that changes to the bits driven by combinatorial cells will be
@ -113,6 +118,12 @@ enum cxxrtl_type {
};
// Flags of a simulated object.
//
// The flags of a simulated object indicate its role in the netlist:
// * The flags `CXXRTL_INPUT` and `CXXRTL_OUTPUT` designate module ports.
// * The flags `CXXRTL_DRIVEN_SYNC`, `CXXRTL_DRIVEN_COMB`, and `CXXRTL_UNDRIVEN` specify
// the semantics of node state. An object with several of these flags set has different bits
// follow different semantics.
enum cxxrtl_flag {
// Node is a module input port.
//
@ -131,6 +142,38 @@ enum cxxrtl_flag {
// This flag can be set on objects of type `CXXRTL_WIRE`. It may be combined with other flags.
CXXRTL_INOUT = (CXXRTL_INPUT|CXXRTL_OUTPUT),
// Node has bits that are driven by a storage cell.
//
// This flag can be set on objects of type `CXXRTL_WIRE`. It may be combined with
// `CXXRTL_DRIVEN_COMB` and `CXXRTL_UNDRIVEN`, as well as other flags.
//
// This flag is set on wires that have bits connected directly to the output of a flip-flop or
// a latch, and hold its state. Many `CXXRTL_WIRE` objects may not have the `CXXRTL_DRIVEN_SYNC`
// flag set; for example, output ports and feedback wires generally won't. Writing to the `next`
// pointer of these wires updates stored state, and for designs without combinatorial loops,
// capturing the value from every of these wires through the `curr` pointer creates a complete
// snapshot of the design state.
CXXRTL_DRIVEN_SYNC = 1 << 2,
// Node has bits that are driven by a combinatorial cell or another node.
//
// This flag can be set on objects of type `CXXRTL_VALUE` and `CXXRTL_WIRE`. It may be combined
// with `CXXRTL_DRIVEN_SYNC` and `CXXRTL_UNDRIVEN`, as well as other flags.
//
// This flag is set on objects that have bits connected to the output of a combinatorial cell,
// or directly to another node. For designs without combinatorial loops, writing to such bits
// through the `next` pointer (if it is not NULL) has no effect.
CXXRTL_DRIVEN_COMB = 1 << 3,
// Node has bits that are not driven.
//
// This flag can be set on objects of type `CXXRTL_VALUE` and `CXXRTL_WIRE`. It may be combined
// with `CXXRTL_DRIVEN_SYNC` and `CXXRTL_DRIVEN_COMB`, as well as other flags.
//
// This flag is set on objects that have bits not driven by an output of any cell or by another
// node, such as inputs and dangling wires.
CXXRTL_UNDRIVEN = 1 << 4,
// More object flags may be added in the future, but the existing ones will never change.
};