PyHDL-IF - A Python Interface to HDL Simulators

PyHDL-IF implements several interfaces between Python and hardware description languages, with a current focus on SystemVerilog.

• Start Python behavior from SystemVerilog/UVM, and interact with UVM classes
• Call SystemVerilog functions and tasks from Python, and invoke Python methods from SystemVerilog
• Use the Python C API, and a SystemVerilog convenience API, to call Python
• Run async pytest tests from SystemVerilog testbenches
• Pass structured data between Python and SystemVerilog using ctypes.Structure

Key Features

Pytest Runner

Run async Python tests directly from SystemVerilog testbenches with pytest's assertion rewriting:

module my_test;
    initial begin
        pyhdl_if::pyhdl_if_start();
        pyhdl_if::pyhdl_pytest("tests/my_async_tests.py");
        $finish;
    end
endmodule

See doc/pytest_runner.md for complete documentation and examples.

Struct Type Support

Pass complex structured data between Python and SystemVerilog using ctypes.Structure:

import ctypes as ct
import hdl_if as hif

class Point(ct.Structure):
    _fields_ = [("x", ct.c_int32), ("y", ct.c_int32)]

@hif.api
class GeometryAPI(object):
    @hif.imp
    async def draw_point(self, p: Point):
        """Called from SystemVerilog"""
        pass

PyHDL-IF automatically generates SystemVerilog struct typedefs and conversion functions. See doc/struct.md for complete documentation.

Installing PyHDL-IF

Installing PyHDL-IF in your own Python virtual environment is easy:

% pip install pyhdl-if

Binary wheels are currently available for Linux x86_64 platforms.

Running Examples

See Examples.md for instructions on how to run examples.

Setting up a Development Environment

PyHDL-IF uses IVPM to manage dependencies. The bootstrap.sh creates a local Python virtual environment, installs IVPM, and required fetches packages.

% ./bootstrap.sh

Building PyHDL-IF

For development builds, PyHDL-IF is built using the Python setup.py script. Run the setup.py script using the local Python virtual environment:

% ./packages/python/bin/python setup.py build_ext --inplace

Running Tests

PyHDL-IF has a growing set of unit tests. These tests assume that you have a recent version of the Verilator SystemVerilog simulator installed.

PyHDL-IF uses pytest for its tests. Run the suite of tests like this:

% PYTHONPATH=$(pwd)/src ./packages/python/bin/python3 -m pytest -s tests/unit

Note: this assumes running bash as the shell.

By default, all available simulators supported by a given test will be run. You can filter the simulators to run using the pytest -k option.

• mti - Siemens Questa (Modeltech)
• xcm - Cadence Xcelium
• vcs - Synopsys VCS
• vlt - Verilator

%  PYTHONPATH=$(pwd)/src ./packages/python/bin/python3 -m pytest -s tests/ -k [vlt]

The command above runs tests with Verilator only.