f4pga/utils/pcf.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright (C) 2019-2022 F4PGA Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# SPDX-License-Identifier: Apache-2.0

"""
Supported PCF commands:
* set_io  <net> <pad> - constrain a given <net> to a given physical <pad> in eFPGA pinout.
* set_clk <pin> <net> - constrain a given global clock <pin> to a given <net>
  Every tile where <net> is present will be constrained to use a given global clock.
"""

from collections import namedtuple
import re

PcfIoConstraint = namedtuple("PcfIoConstraint", "net pad line_str line_num")
PcfClkConstraint = namedtuple("PcfClkConstraint", "pin net")


def parse_simple_pcf(f):
    """Parse a simple PCF file object and yield PcfIoConstraint objects."""
    for line_number, line in enumerate(f):
        line_number += 1

        # Remove comments.
        args = re.sub(r"#.*", "", line.strip()).split()

        if not args:
            continue

        # Ignore arguments.
        args = [arg for arg in args if arg[0] != "-"]
        assert len(args) == 3, args

        if args[0] == "set_io":
            yield PcfIoConstraint(
                net=args[1],
                pad=args[2],
                line_str=line.strip(),
                line_num=line_number,
            )

        if args[0] == "set_clk":
            yield PcfClkConstraint(
                pin=args[1],
                net=args[2],
            )