Method validateChecksum

src/OpenLoco/src/S5/SawyerStream.cpp:55–88

}

bool SawyerStreamReader::validateChecksum()
{
    auto valid = false;
    auto backupPos = _stream.getPosition();
    auto fileLength = static_cast<uint32_t>(_stream.getLength());
    if (fileLength >= 4)
    {
        // Read checksum
        uint32_t checksum;
        _stream.setPosition(fileLength - 4);
        _stream.read(&checksum, sizeof(checksum));

        // Calculate checksum
        uint32_t actualChecksum = 0;
        _stream.setPosition(0);
        uint8_t buffer[2048];
        for (uint32_t i = 0; i < fileLength - 4; i += sizeof(buffer))
        {
            auto readLength = std::min<size_t>(sizeof(buffer), fileLength - 4 - i);
            _stream.read(buffer, readLength);
            for (size_t j = 0; j < readLength; j++)
            {
                actualChecksum += buffer[j];
            }
        }

        valid = checksum == actualChecksum;
    }

    // Restore position
    _stream.setPosition(backupPos);

    return valid;
}

std::span<const std::byte> SawyerStreamReader::decode(SawyerEncoding encoding, std::span<const std::byte> data)
{