The-OpenROAD-Project_OpenSTA/power/VcdParse.cc

// OpenSTA, Static Timing Analyzer
// Copyright (c) 2026, Parallax Software, Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software.
//
// Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
//
// This notice may not be removed or altered from any source distribution.

#include "VcdParse.hh"

#include <algorithm>
#include <cctype>
#include <cinttypes>

#include "EnumNameMap.hh"
#include "Error.hh"
#include "Report.hh"
#include "Stats.hh"

namespace sta {

// Very imprecise syntax definition
// https://en.wikipedia.org/wiki/Value_change_dump#Structure.2FSyntax
// Much better syntax definition
// https://web.archive.org/web/20120323132708/http://www.beyondttl.com/vcd.php

void
VcdParse::read(const char *filename,
               VcdReader *reader,
               VcdTime begin_time,
               VcdTime end_time)
{
  begin_time_ = begin_time;
  end_time_ = end_time;

  stream_ = gzopen(filename, "r");
  if (stream_) {
    Stats stats(debug_, report_);
    filename_ = filename;
    reader_ = reader;
    file_line_ = 0;
    stmt_line_ = 0;

    // If user specified a start time, set it now.
    if (begin_time != vcd_null_time) {
      reader_->setTimeMin(begin_time);
    }
    std::string token = getToken();
    while (!token.empty()) {
      if (token == "$date")
        reader_->setDate(readStmtString());
      else if (token == "$comment")
        reader_->setComment(readStmtString());
      else if (token == "$version")
        reader_->setVersion(readStmtString());
      else if (token == "$timescale")
        parseTimescale();
      else if (token == "$var")
        parseVar();
      else if (token == "$scope")
        parseScope();
      else if (token == "$upscope")
        parseUpscope();
      else if (token == "$enddefinitions")
        // empty body
        readStmtString();
      else if (token == "$dumpall")
        // Ignore dumpall body.
        readStmtTokens();
      // Read initial values
      else if (token == "$dumpvars")
        // Initial values.
        parseVarValues();
      else if (token[0] == '#') {
        try {
          time_ = stoll(token.substr(1));
        } catch (std::invalid_argument &error) {
          report_->fileError(805, filename_, file_line_, "invalid time {}",
                             token.substr(1));
        } catch (std::out_of_range &error) {
          report_->fileError(806, filename_, file_line_, "time out of range {}",
                             token.substr(1));
        }
        // Set time min to start time if it is not set at beginning
        if (begin_time == vcd_null_time) {
          reader_->setTimeMin(time_);
        }
        prev_time_ = time_;
      }
      else if (token[0] == '$')
        report_->fileError(800, filename_, file_line_, "unknown vcd command.");
      else
        parseVarValues();

      token = getToken();
    }
    gzclose(stream_);
    stats.report("Read VCD");
  }
  else
    throw FileNotReadable(filename);
}

VcdParse::VcdParse(Report *report,
                   Debug *debug) :
  report_(report),
  debug_(debug)
{
}

void
VcdParse::parseTimescale()
{
  std::vector<std::string> tokens = readStmtTokens();
  if (tokens.size() == 1) {
    size_t last;
    double time_scale = std::stod(tokens[0], &last);
    setTimeUnit(tokens[0].substr(last), time_scale);
  }
  else if (tokens.size() == 2) {
    double time_scale = std::stod(tokens[0]);
    setTimeUnit(tokens[1], time_scale);
  }
  else
    report_->fileError(801, filename_, file_line_, "timescale syntax error.");
}

void
VcdParse::setTimeUnit(std::string_view time_unit,
                      double time_scale)
{
  double time_unit_scale = 1.0;
  if (time_unit == "fs")
    time_unit_scale = 1e-15;
  else if (time_unit == "ps")
    time_unit_scale = 1e-12;
  else if (time_unit == "ns")
    time_unit_scale = 1e-9;
  else
    report_->fileError(802, filename_, file_line_, "Unknown timescale unit.");
  reader_->setTimeUnit(time_unit, time_unit_scale, time_scale);
}

static EnumNameMap<VcdVarType> vcd_var_type_map = {
    {VcdVarType::wire, "wire"},
    {VcdVarType::reg, "reg"},
    {VcdVarType::parameter, "parameter"},
    {VcdVarType::integer, "integer"},
    {VcdVarType::real, "real"},
    {VcdVarType::supply0, "supply0"},
    {VcdVarType::supply1, "supply1"},
    {VcdVarType::time, "time"},
    {VcdVarType::tri, "tri"},
    {VcdVarType::triand, "triand"},
    {VcdVarType::trior, "trior"},
    {VcdVarType::trireg, "trireg"},
    {VcdVarType::tri0, "tri0"},
    {VcdVarType::tri1, "tri1"},
    {VcdVarType::wand, "wand"},
    {VcdVarType::wor, "wor"}};

void
VcdParse::parseVar()
{
  std::vector<std::string> tokens = readStmtTokens();
  if (tokens.size() == 4 || tokens.size() == 5) {
    std::string &type_name = tokens[0];
    VcdVarType type = vcd_var_type_map.find(type_name, VcdVarType::unknown);
    if (type == VcdVarType::unknown)
      report_->fileWarn(809, filename_, file_line_, "Unknown variable type {}.",
                        type_name);
    else {
      size_t width = std::stoi(tokens[1]);
      std::string &id = tokens[2];
      std::string &name = tokens[3];
      // iverilog separates bus base name from bit range.
      if (tokens.size() == 5) {
        // Preserve space after esacaped name.
        if (name[0] == '\\')
          name += ' ';
        name += tokens[4];
      }
      reader_->makeVar(scope_, name, type, width, id);
    }
  }
  else
    report_->fileError(804, filename_, file_line_, "Variable syntax error.");
}

void
VcdParse::parseScope()
{
  std::vector<std::string> tokens = readStmtTokens();
  std::string &scope = tokens[1];
  scope_.push_back(scope);
}

void
VcdParse::parseUpscope()
{
  readStmtTokens();
  scope_.pop_back();
}

void
VcdParse::parseVarValues()
{
  std::string token = getToken();
  while (!token.empty()) {
    char char0 = toupper(token[0]);
    if (char0 == '#' && token.size() > 1) {
      VcdTime time = std::stoll(token.substr(1));
      prev_time_ = time_;
      time_ = time;
      if (time_ > prev_time_)
        reader_->varMinDeltaTime(time_ - prev_time_);
    }
    else if (char0 == '0' || char0 == '1' || char0 == 'X' || char0 == 'U'
             || char0 == 'Z') {
      std::string id = token.substr(1);
      if (!reader_->varIdValid(id))
        report_->fileError(808, filename_, file_line_, "unknown variable {}", id);
      reader_->varAppendValue(id, time_, char0);
    }
    else if (char0 == 'B') {
      std::string bus_value = token.substr(1);
      std::string id = getToken();
      if (!reader_->varIdValid(id))
        report_->fileError(807, filename_, file_line_, "unknown variable {}", id);
      else {
        // Reverse the bus value to match the bit order in the VCD file.
        std::ranges::reverse(bus_value);
        reader_->varAppendBusValue(id, time_, bus_value);
      }
    }
    token = getToken();
  }

  // Set time_max to end_time if specified, otherwise use actual parsed time
  if (end_time_ != vcd_null_time) {
    reader_->setTimeMax(end_time_);
  } else {
    reader_->setTimeMax(time_);
  }
}

std::string
VcdParse::readStmtString()
{
  stmt_line_ = file_line_;
  std::string line;
  std::string token = getToken();
  while (!token.empty() && token != "$end") {
    if (!line.empty())
      line += " ";
    line += token;
    token = getToken();
  }
  return line;
}

std::vector<std::string>
VcdParse::readStmtTokens()
{
  stmt_line_ = file_line_;
  std::vector<std::string> tokens;
  std::string token = getToken();
  while (!token.empty() && token != "$end") {
    tokens.push_back(token);
    token = getToken();
  }
  return tokens;
}

std::string
VcdParse::getToken()
{
  std::string token;
  int ch = gzgetc(stream_);
  // skip whitespace
  while (ch != EOF && std::isspace(ch)) {
    if (ch == '\n')
      file_line_++;
    ch = gzgetc(stream_);
  }
  while (ch != EOF && !std::isspace(ch)) {
    token.push_back(ch);
    ch = gzgetc(stream_);
  }
  if (ch == '\n')
    file_line_++;
  if (ch == EOF)
    return "";
  else
    return token;
}

////////////////////////////////////////////////////////////////

char
VcdValue::value(int value_bit) const
{
  if (value_ == '\0')
    return ((bus_value_ >> value_bit) & 0x1) ? '1' : '0';
  else
    return value_;
}

void
VcdValue::setValue(VcdTime time,
                   char value)
{
  time_ = time;
  value_ = value;
}

}  // namespace sta