Method StartDataRead

engine/Poseidon/Audio/Core/Format/WaveFile.cpp:148–196

Must run before Read: scans forward from just after the format to the 'data' chunk to descend into, skipping leading chunks such as 'fact'.

// Must run before Read: scans forward from just after the format to the 'data'
// chunk to descend into, skipping leading chunks such as 'fact'.
void WaveFile::StartDataRead()
{
    if (error)
    {
        return;
    }

    RiffChunk chunk;
    int lastPos = -1;
    for (;;)
    {
        // A huge/overflowing chunk length can leave the cursor at or before its prior
        // position (the seeks below clamp or fail), looping the search forever; bail
        // if an iteration made no forward progress.
        const int pos = _file.tellg();
        if (pos <= lastPos)
        {
            error = true;
            break;
        }
        lastPos = pos;
        _file.read(&chunk, sizeof(chunk));
        if (_file.fail())
        {
            error = true;
            break;
        }
        if (chunk.id == RIFF_fact)
        {
            DWORD fact;
            _file.read(&fact, sizeof(fact));
            _file.seekg(chunk.len - sizeof(fact), QIOS::cur);
            _samples = fact;
        }
        else if (chunk.id == RIFF_data)
        {
            _dataSize = chunk.len;
            _dataRest = chunk.len;
            _dataOffset = _file.tellg();
            break;
        }
        else
        {
            // skip chunk
            _file.seekg(chunk.len, QIOS::cur);
            continue;
        }
    }
}

// Reads from the data chunk; StartDataRead must have descended into it first.
UINT WaveFile::Read(UINT cbRead, char* Dest)