verilator/nodist/verilator_saif_diff

#!/usr/bin/env python3
# pylint: disable=C0114,C0115,C0116,R0902,R0903,R0912,R0915,W0719,W0718
######################################################################
#
# Copyright 2025 by Wilson Snyder. This program is free software; you
# can redistribute it and/or modify it under the terms of either the GNU
# Lesser General Public License Version 3 or the Perl Artistic License
# Version 2.0.
# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0

import argparse
import re

SUCCESS_CODE = 0
FAILURE_CODE = 1
INSTANCE_TYPE = "INSTANCE"
NET_LIST_TYPE = "NET"
SIGNAL_TYPE = "SIGNAL"
EOF_ERROR = "Unexpected EOF"


def saif_assert(expression, message):
    if not expression:
        raise Exception(message)


def saif_error(message):
    raise Exception(message)


class SAIFSignalBit:
    name: str
    high_time: int
    low_time: int
    transitions: int

    def __init__(self, name):
        self.name = name
        self.high_time = 0
        self.low_time = 0
        self.transitions = 0


class SAIFInstance:

    def __init__(self, scope_name):
        self.scope_name = scope_name
        self.parent_instance = None
        self.nets = {}
        self.child_instances = {}


class SAIFToken:

    def __init__(self, token):
        self.token = token
        self.type = ''
        self.value = ''


class SAIFParser:

    def __init__(self):
        self.token_stack = []
        # For parsing simplicity
        self.token_stack.append(SAIFToken('saif_root'))
        self.current_instance = None
        self.has_saifile_header = False
        self.direction = ''
        self.saif_version = ''
        self.top_instances = {}
        self.duration = 0
        self.divider = ''
        self.timescale = ''

    def parse(self, saif_filename):
        file_contents = ''
        with open(saif_filename, 'r', encoding="utf8") as saif_file:
            content = saif_file.readlines()
            filtered_lines = [line for line in content if not line.strip().startswith('//')]
            file_contents = ''.join(filtered_lines)
        tokens = file_contents.replace('(', ' ( ').replace(')', ' ) ').split()
        num_of_tokens = len(tokens)
        index = 0
        while index < num_of_tokens:
            token = tokens[index]
            index += 1
            if token == '(':
                self.token_stack.append(SAIFToken(token))
                self.token_stack[-1].type = self.token_stack[-2].type
                self.token_stack[-1].value = self.token_stack[-2].value
                continue
            if token == ')':
                if self.token_stack[-1].type == INSTANCE_TYPE:
                    self.current_instance = self.current_instance.parent_instance
                self.token_stack.pop()
                continue
            if re.match(r'SAIFILE', token):
                self.has_saifile_header = True
                continue
            if re.match(r'DIRECTION', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.direction = tokens[index].replace('\"', '')
                index += 1
                continue
            if re.match(r'SAIFVERSION', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.saif_version = tokens[index].replace('\"', '')
                index += 1
                continue
            if re.match(r'DESIGN|DATE|VENDOR|PROGRAM_NAME|VERSION', token):
                # NOP, only skip value
                saif_assert(index < num_of_tokens, EOF_ERROR)
                index += 1
                continue
            if re.match(r'DIVIDER', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.divider = tokens[index]
                index += 1
                continue
            if re.match(r'TIMESCALE', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.timescale = tokens[index]
                index += 1
                continue
            if re.match(r'DURATION', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.duration = tokens[index]
                index += 1
                continue
            if re.match(r'INSTANCE', token):
                saif_assert(index < num_of_tokens, EOF_ERROR)
                instance_name = tokens[index]
                index += 1
                self.token_stack[-1].type = INSTANCE_TYPE
                self.token_stack[-1].value = instance_name
                instance = SAIFInstance(instance_name)
                if self.current_instance is None:
                    self.top_instances[instance_name] = instance
                else:
                    self.current_instance.child_instances[instance_name] = instance
                instance.parent_instance = self.current_instance
                self.current_instance = instance
                continue
            if re.match(r'NET', token):
                self.token_stack[-1].type = NET_LIST_TYPE
                continue
            if re.match(r'T1', token):
                net_name = self.token_stack[-1].value
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.current_instance.nets[net_name].high_time = tokens[index]
                index += 1
                continue
            if re.match(r'T0', token):
                net_name = self.token_stack[-1].value
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.current_instance.nets[net_name].low_time = tokens[index]
                index += 1
                continue
            if re.match(r'TC', token):
                net_name = self.token_stack[-1].value
                saif_assert(index < num_of_tokens, EOF_ERROR)
                self.current_instance.nets[net_name].transitions = tokens[index]
                index += 1
                continue
            if re.match(r'TZ|TX|TB|TG|IG|IK', token):
                # NOP, only skip value
                index += 1
                continue
            if self.token_stack[-2].type == NET_LIST_TYPE:
                self.token_stack[-1].type = SIGNAL_TYPE
                self.token_stack[-1].value = token
                self.current_instance.nets[token] = SAIFSignalBit(token)
        saif_assert(self.has_saifile_header, "SAIF file doesn't contain a SAIFILE keyword")
        saif_assert(self.direction == "backward",
                    f"SAIF file doesn't have a valid/compatible direction: {self.direction}")
        saif_assert(self.saif_version == "2.0",
                    f"SAIF file doesn't have a valid/compatible version: {self.saif_version}")
        # Only 'saif_root' token should be left
        saif_assert(len(self.token_stack) == 1, "Incorrect nesting of scopes")


def compare_saif_instances(first: SAIFInstance, second: SAIFInstance):
    if len(first.nets) != len(second.nets):
        saif_error(f"Number of nets doesn't match in {first.scope_name}: "
                   f"{len(first.nets)} != {len(second.nets)}")
    for signal_name, saif_signal in first.nets.items():
        if signal_name not in second.nets:
            saif_error(f"Signal {signal_name} doesn't exist in the second object\n")
        other_signal = second.nets[signal_name]
        if (saif_signal.high_time != other_signal.high_time
                or saif_signal.low_time != other_signal.low_time
                or saif_signal.transitions != other_signal.transitions):
            saif_error("Incompatible signal bit parameters in "
                       f"{signal_name}\n")
    if len(first.child_instances) != len(second.child_instances):
        saif_error(f"Number of child instances doesn't match in {first.scope_name}: "
                   f"{len(first.child_instances)} != {len(second.child_instances)}")
    for instance_name, instance in first.child_instances.items():
        if instance_name not in second.child_instances:
            saif_error(f"Instance {instance_name} doesn't exist in the second object\n")
        compare_saif_instances(instance, second.child_instances[instance_name])


def compare_saif_contents(first_file: str, second_file: str):
    """Test if second SAIF file has the same values as the first"""
    first_saif = SAIFParser()
    first_saif.parse(first_file)
    second_saif = SAIFParser()
    second_saif.parse(second_file)
    if first_saif.duration != second_saif.duration:
        saif_error("Duration of trace doesn't match: "
                   f"{first_saif.duration} != {second_saif.duration}")
    if first_saif.divider != second_saif.divider:
        saif_error(f"Dividers don't match: {first_saif.divider} != {second_saif.divider}")
    if first_saif.timescale != second_saif.timescale:
        saif_error(f"Timescale doesn't match: {first_saif.timescale} != {second_saif.timescale}")
    if len(first_saif.top_instances) != len(second_saif.top_instances):
        saif_error("Number of top instances doesn't match: "
                   f"{len(first_saif.top_instances)} != {len(second_saif.top_instances)}")
    for top_instance_name, top_instance in first_saif.top_instances.items():
        if top_instance_name not in second_saif.top_instances:
            saif_error(f"Top instance {top_instance_name} missing in other SAIF")
        compare_saif_instances(top_instance, second_saif.top_instances[top_instance_name])
    return SUCCESS_CODE


parser = argparse.ArgumentParser(allow_abbrev=False,
                                 formatter_class=argparse.RawDescriptionHelpFormatter,
                                 description="""verilator_saif_diff checks if two SAIF files are logically-identical. It returns first encountered difference as output.
Run as:
  cd $VERILATOR_ROOT
  nodist/code_coverage --first example.saif --second other.saif""")
parser.add_argument('--first', action='store', help='First SAIF file')
parser.add_argument('--second', action='store', help='Second SAIF file')
parser.set_defaults(stop=True)
args = parser.parse_args()
try:
    compare_saif_contents(args.first, args.second)
except Exception as error:
    print(error)