verilog-parser

A pure-Python parser for Verilog cell-library (.v) files — used in EDA flows to describe the pins and port directions of standard cells.

Related article

Building a Python Verilog Cell Library Parser for EDA Automation — A walkthrough of the design decisions and real-world use cases behind this library.

Features

• Parses `celldefine / `endcelldefine blocks with module, input, output, and inout declarations
• Supports mixed and non-mixed mode variants via `ifdef MIXEDMODE
• Zero required dependencies — only the Python standard library
• Optional colored warnings via termcolor
• CLI included: verilog-parser cells.v --cell INV_X1

Installation

pip install eda-verilog-parser                  # no extra dependencies
pip install "eda-verilog-parser[color]"         # adds termcolor for colored warnings

Or for development:

git clone https://github.com/rohaansch/verilog-parser
cd verilog-parser
pip install -e ".[dev]"

Quick start

from verilog_parser import VerilogParser

parser = VerilogParser()
verilog = parser.read("cells.v")

print(repr(verilog))
# Verilog(cells=4, files=1)

print(verilog.get_pins("INV_X1"))
# ['A', 'ZN']

print(verilog.get_pin_directions("INV_X1"))
# {'input': ['A'], 'output': ['ZN'], 'inout': []}

print(verilog.get_pin_directions("INV_X1", mode="mixed"))
# {'input': ['A'], 'output': [], 'inout': ['ZN']}

Supported Verilog structure

The parser recognises cells defined with `celldefine / `endcelldefine and `ifdef MIXEDMODE / `else / `endif sections:

`celldefine
`ifdef MIXEDMODE
module INV_X1 (A, ZN);
  input A;
  inout ZN;
`else
module INV_X1 (A, ZN);
  input A;
  output ZN;
`endif
`endcelldefine

Modes

Mode	When used
"non-mixed" (default)	Digital-only simulation; outputs declared as output
"mixed"	Mixed-signal simulation; outputs declared as inout

API reference

VerilogParser(path=None)

Create a parser. path sets the default file used by read().

VerilogParser.read(path=None) → Verilog

Argument	Type	Description
path	str	.v file path. Falls back to the constructor path.

Raises ValueError / FileNotFoundError / IOError on bad input.

VerilogParser.reset()

Clear internal state to reuse the parser for a different file:

v_fast = parser.read("lib_fast.v")
parser.reset()
v_slow = parser.read("lib_slow.v")

Verilog object

Attribute	Type	Description
header	str	Leading comment block from the parsed file
cells	dict[str, dict]	Cell name → mode → pin data
files	list[str]	Absolute paths of files contributing to this object

Verilog.get_pins(cell_name, mode="non-mixed") → list[str]

Return the ordered list of all pins for the given cell and mode.

Verilog.get_pin_directions(cell_name, mode="non-mixed") → dict

Return a mapping of "input" / "output" / "inout" → pin list.

format_cell(cell) → str

Format a cell's mode data as a human-readable multi-line string:

from verilog_parser import format_cell
print(format_cell(verilog.cells["DFFS_X2"]))
# [mixed]
#     pins:   D, CK, SN, Q, QN
#     input:  D, CK, SN
#     inout:  Q, QN
# [non-mixed]
#     pins:   D, CK, SN, Q, QN
#     input:  D, CK, SN
#     output: Q, QN

Command-line usage

verilog-parser cells.v
verilog-parser cells.v --cell INV_X1
verilog-parser cells.v --cell INV_X1 --mode mixed
verilog-parser cells.v --header
verilog-parser --version

Or without installing:

python -m verilog_parser cells.v --cell INV_X1

Running the tests

pip install -e ".[dev]"
pytest -v

License

MIT