m_pwfx = NULL;

    if( ( 0 != mmioDescend( m_hmmio, &m_ckRiff, NULL, 0 ) ) )
        return DXTRACE_ERR( TEXT("mmioDescend"), E_FAIL );

    // Check to make sure this is a valid wave file
    if( (m_ckRiff.ckid != FOURCC_RIFF) ||
        (m_ckRiff.fccType != mmioFOURCC('W', 'A', 'V', 'E') ) )
        return DXTRACE_ERR_NOMSGBOX( TEXT("mmioFOURCC"), E_FAIL ); 

    // Search the input file for for the 'fmt ' chunk.
    ckIn.ckid = mmioFOURCC('f', 'm', 't', ' ');
    if( 0 != mmioDescend( m_hmmio, &ckIn, &m_ckRiff, MMIO_FINDCHUNK ) )
        return DXTRACE_ERR( TEXT("mmioDescend"), E_FAIL );

    // Expect the 'fmt' chunk to be at least as large as <PCMWAVEFORMAT>;
    // if there are extra parameters at the end, we'll ignore them
       if( ckIn.cksize < (LONG) sizeof(PCMWAVEFORMAT) )
           return DXTRACE_ERR( TEXT("sizeof(PCMWAVEFORMAT)"), E_FAIL );

    // Read the 'fmt ' chunk into <pcmWaveFormat>.
    if( mmioRead( m_hmmio, (HPSTR) &pcmWaveFormat, 
                  sizeof(pcmWaveFormat)) != sizeof(pcmWaveFormat) )
        return DXTRACE_ERR( TEXT("mmioRead"), E_FAIL );

    // Allocate the waveformatex, but if its not pcm format, read the next
    // word, and thats how many extra bytes to allocate.
    if( pcmWaveFormat.wf.wFormatTag == WAVE_FORMAT_PCM )
    {
        m_pwfx = (WAVEFORMATEX*)new CHAR[ sizeof(WAVEFORMATEX) ];
        if( NULL == m_pwfx )
            return DXTRACE_ERR( TEXT("m_pwfx"), E_FAIL );

        // Copy the bytes from the pcm structure to the waveformatex structure
        memcpy( m_pwfx, &pcmWaveFormat, sizeof(pcmWaveFormat) );
        m_pwfx->cbSize = 0;
    }
    else
    {
        // Read in length of extra bytes.
        WORD cbExtraBytes = 0L;
        if( mmioRead( m_hmmio, (CHAR*)&cbExtraBytes, sizeof(WORD)) != sizeof(WORD) )
            return DXTRACE_ERR( TEXT("mmioRead"), E_FAIL );

        m_pwfx = (WAVEFORMATEX*)new CHAR[ sizeof(WAVEFORMATEX) + cbExtraBytes ];
        if( NULL == m_pwfx )
            return DXTRACE_ERR( TEXT("new"), E_FAIL );

        // Copy the bytes from the pcm structure to the waveformatex structure
        memcpy( m_pwfx, &pcmWaveFormat, sizeof(pcmWaveFormat) );
        m_pwfx->cbSize = cbExtraBytes;

        // Now, read those extra bytes into the structure, if cbExtraAlloc != 0.
        if( mmioRead( m_hmmio, (CHAR*)(((BYTE*)&(m_pwfx->cbSize))+sizeof(WORD)),
                      cbExtraBytes ) != cbExtraBytes )
        {
            SAFE_DELETE( m_pwfx );
            return DXTRACE_ERR( TEXT("mmioRead"), E_FAIL );
        }
    }

    // Ascend the input file out of the 'fmt ' chunk.
    if( 0 != mmioAscend( m_hmmio, &ckIn, 0 ) )
    {
        SAFE_DELETE( m_pwfx );
        return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
    }

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::GetSize()
// Desc: Retuns the size of the read access wave file 
//-----------------------------------------------------------------------------
DWORD CWaveFile::GetSize()
{
    return m_dwSize;
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::ResetFile()
// Desc: Resets the internal m_ck pointer so reading starts from the 
//       beginning of the file again 
//-----------------------------------------------------------------------------
HRESULT CWaveFile::ResetFile()
{
    if( m_bIsReadingFromMemory )
    {
        m_pbDataCur = m_pbData;
    }
    else 
    {
        if( m_hmmio == NULL )
            return CO_E_NOTINITIALIZED;

        if( m_dwFlags == WAVEFILE_READ )
        {
            // Seek to the data
            if( -1 == mmioSeek( m_hmmio, m_ckRiff.dwDataOffset + sizeof(FOURCC),
                            SEEK_SET ) )
                return DXTRACE_ERR( TEXT("mmioSeek"), E_FAIL );

            // Search the input file for the 'data' chunk.
            m_ck.ckid = mmioFOURCC('d', 'a', 't', 'a');
            if( 0 != mmioDescend( m_hmmio, &m_ck, &m_ckRiff, MMIO_FINDCHUNK ) )
              return DXTRACE_ERR( TEXT("mmioDescend"), E_FAIL );
        }
        else
        {
            // Create the 'data' chunk that holds the waveform samples.  
            m_ck.ckid = mmioFOURCC('d', 'a', 't', 'a');
            m_ck.cksize = 0;

            if( 0 != mmioCreateChunk( m_hmmio, &m_ck, 0 ) ) 
                return DXTRACE_ERR( TEXT("mmioCreateChunk"), E_FAIL );

            if( 0 != mmioGetInfo( m_hmmio, &m_mmioinfoOut, 0 ) )
                return DXTRACE_ERR( TEXT("mmioGetInfo"), E_FAIL );
        }
    }
    
    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::Read()
// Desc: Reads section of data from a wave file into pBuffer and returns 
//       how much read in pdwSizeRead, reading not more than dwSizeToRead.
//       This uses m_ck to determine where to start reading from.  So 
//       subsequent calls will be continue where the last left off unless 
//       Reset() is called.
//-----------------------------------------------------------------------------
HRESULT CWaveFile::Read( BYTE* pBuffer, DWORD dwSizeToRead, DWORD* pdwSizeRead )
{
    if( m_bIsReadingFromMemory )
    {
        if( m_pbDataCur == NULL )
            return CO_E_NOTINITIALIZED;
        if( pdwSizeRead != NULL )
            *pdwSizeRead = 0;

        if( (BYTE*)(m_pbDataCur + dwSizeToRead) > 
            (BYTE*)(m_pbData + m_ulDataSize) )
        {
            dwSizeToRead = m_ulDataSize - (DWORD)(m_pbDataCur - m_pbData);
        }
        
        CopyMemory( pBuffer, m_pbDataCur, dwSizeToRead );
        
        if( pdwSizeRead != NULL )
            *pdwSizeRead = dwSizeToRead;

        return S_OK;
    }
    else 
    {
        MMIOINFO mmioinfoIn; // current status of m_hmmio

        if( m_hmmio == NULL )
            return CO_E_NOTINITIALIZED;
        if( pBuffer == NULL || pdwSizeRead == NULL )
            return E_INVALIDARG;

        if( pdwSizeRead != NULL )
            *pdwSizeRead = 0;

        if( 0 != mmioGetInfo( m_hmmio, &mmioinfoIn, 0 ) )
            return DXTRACE_ERR( TEXT("mmioGetInfo"), E_FAIL );
                
        UINT cbDataIn = dwSizeToRead;
        if( cbDataIn > m_ck.cksize ) 
            cbDataIn = m_ck.cksize;       

        m_ck.cksize -= cbDataIn;
    
        for( DWORD cT = 0; cT < cbDataIn; cT++ )
        {
            // Copy the bytes from the io to the buffer.
            if( mmioinfoIn.pchNext == mmioinfoIn.pchEndRead )
            {
                if( 0 != mmioAdvance( m_hmmio, &mmioinfoIn, MMIO_READ ) )
                    return DXTRACE_ERR( TEXT("mmioAdvance"), E_FAIL );

                if( mmioinfoIn.pchNext == mmioinfoIn.pchEndRead )
                    return DXTRACE_ERR( TEXT("mmioinfoIn.pchNext"), E_FAIL );
            }

            // Actual copy.
            *((BYTE*)pBuffer+cT) = *((BYTE*)mmioinfoIn.pchNext);
            mmioinfoIn.pchNext++;
        }

        if( 0 != mmioSetInfo( m_hmmio, &mmioinfoIn, 0 ) )
            return DXTRACE_ERR( TEXT("mmioSetInfo"), E_FAIL );

        if( pdwSizeRead != NULL )
            *pdwSizeRead = cbDataIn;

        return S_OK;
    }
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::Close()
// Desc: Closes the wave file 
//-----------------------------------------------------------------------------
HRESULT CWaveFile::Close()
{
    if( m_dwFlags == WAVEFILE_READ )
    {
        mmioClose( m_hmmio, 0 );
        m_hmmio = NULL;
    }
    else
    {
        m_mmioinfoOut.dwFlags |= MMIO_DIRTY;

        if( m_hmmio == NULL )
            return CO_E_NOTINITIALIZED;

        if( 0 != mmioSetInfo( m_hmmio, &m_mmioinfoOut, 0 ) )
            return DXTRACE_ERR( TEXT("mmioSetInfo"), E_FAIL );
    
        // Ascend the output file out of the 'data' chunk -- this will cause
        // the chunk size of the 'data' chunk to be written.
        if( 0 != mmioAscend( m_hmmio, &m_ck, 0 ) )
            return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
    
        // Do this here instead...
        if( 0 != mmioAscend( m_hmmio, &m_ckRiff, 0 ) )
            return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
        
        mmioSeek( m_hmmio, 0, SEEK_SET );

        if( 0 != (INT)mmioDescend( m_hmmio, &m_ckRiff, NULL, 0 ) )
            return DXTRACE_ERR( TEXT("mmioDescend"), E_FAIL );
    
        m_ck.ckid = mmioFOURCC('f', 'a', 'c', 't');

        if( 0 == mmioDescend( m_hmmio, &m_ck, &m_ckRiff, MMIO_FINDCHUNK ) ) 
        {
            DWORD dwSamples = 0;
            mmioWrite( m_hmmio, (HPSTR)&dwSamples, sizeof(DWORD) );
            mmioAscend( m_hmmio, &m_ck, 0 ); 
        }
    
        // Ascend the output file out of the 'RIFF' chunk -- this will cause
        // the chunk size of the 'RIFF' chunk to be written.
        if( 0 != mmioAscend( m_hmmio, &m_ckRiff, 0 ) )
            return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
    
        mmioClose( m_hmmio, 0 );
        m_hmmio = NULL;
    }

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::WriteMMIO()
// Desc: Support function for reading from a multimedia I/O stream
//       pwfxDest is the WAVEFORMATEX for this new wave file.  
//       m_hmmio must be valid before calling.  This function uses it to
//       update m_ckRiff, and m_ck.  
//-----------------------------------------------------------------------------
HRESULT CWaveFile::WriteMMIO( WAVEFORMATEX *pwfxDest )
{
    DWORD    dwFactChunk; // Contains the actual fact chunk. Garbage until WaveCloseWriteFile.
    MMCKINFO ckOut1;
    
    dwFactChunk = (DWORD)-1;

    // Create the output file RIFF chunk of form type 'WAVE'.
    m_ckRiff.fccType = mmioFOURCC('W', 'A', 'V', 'E');       
    m_ckRiff.cksize = 0;

    if( 0 != mmioCreateChunk( m_hmmio, &m_ckRiff, MMIO_CREATERIFF ) )
        return DXTRACE_ERR( TEXT("mmioCreateChunk"), E_FAIL );
    
    // We are now descended into the 'RIFF' chunk we just created.
    // Now create the 'fmt ' chunk. Since we know the size of this chunk,
    // specify it in the MMCKINFO structure so MMIO doesn't have to seek
    // back and set the chunk size after ascending from the chunk.
    m_ck.ckid = mmioFOURCC('f', 'm', 't', ' ');
    m_ck.cksize = sizeof(PCMWAVEFORMAT);   

    if( 0 != mmioCreateChunk( m_hmmio, &m_ck, 0 ) )
        return DXTRACE_ERR( TEXT("mmioCreateChunk"), E_FAIL );
    
    // Write the PCMWAVEFORMAT structure to the 'fmt ' chunk if its that type. 
    if( pwfxDest->wFormatTag == WAVE_FORMAT_PCM )
    {
        if( mmioWrite( m_hmmio, (HPSTR) pwfxDest, 
                       sizeof(PCMWAVEFORMAT)) != sizeof(PCMWAVEFORMAT))
            return DXTRACE_ERR( TEXT("mmioWrite"), E_FAIL );
    }   
    else 
    {
        // Write the variable length size.
        if( (UINT)mmioWrite( m_hmmio, (HPSTR) pwfxDest, 
                             sizeof(*pwfxDest) + pwfxDest->cbSize ) != 
                             ( sizeof(*pwfxDest) + pwfxDest->cbSize ) )
            return DXTRACE_ERR( TEXT("mmioWrite"), E_FAIL );
    }  
    
    // Ascend out of the 'fmt ' chunk, back into the 'RIFF' chunk.
    if( 0 != mmioAscend( m_hmmio, &m_ck, 0 ) )
        return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
    
    // Now create the fact chunk, not required for PCM but nice to have.  This is filled
    // in when the close routine is called.
    ckOut1.ckid = mmioFOURCC('f', 'a', 'c', 't');
    ckOut1.cksize = 0;

    if( 0 != mmioCreateChunk( m_hmmio, &ckOut1, 0 ) )
        return DXTRACE_ERR( TEXT("mmioCreateChunk"), E_FAIL );
    
    if( mmioWrite( m_hmmio, (HPSTR)&dwFactChunk, sizeof(dwFactChunk)) != 
                    sizeof(dwFactChunk) )
         return DXTRACE_ERR( TEXT("mmioWrite"), E_FAIL );
    
    // Now ascend out of the fact chunk...
    if( 0 != mmioAscend( m_hmmio, &ckOut1, 0 ) )
        return DXTRACE_ERR( TEXT("mmioAscend"), E_FAIL );
       
    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CWaveFile::Write()
// Desc: Writes data to the open wave file
//-----------------------------------------------------------------------------
HRESULT CWaveFile::Write( UINT nSizeToWrite, BYTE* pbSrcData, UINT* pnSizeWrote )
{
    UINT cT;

    if( m_bIsReadingFromMemory )
        return E_NOTIMPL;
    if( m_hmmio == NULL )
        return CO_E_NOTINITIALIZED;
    if( pnSizeWrote == NULL || pbSrcData == NULL )
        return E_INVALIDARG;

    *pnSizeWrote = 0;
    
    for( cT = 0; cT < nSizeToWrite; cT++ )
    {       
        if( m_mmioinfoOut.pchNext == m_mmioinfoOut.pchEndWrite )
        {
            m_mmioinfoOut.dwFlags |= MMIO_DIRTY;
            if( 0 != mmioAdvance( m_hmmio, &m_mmioinfoOut, MMIO_WRITE ) )
                return DXTRACE_ERR( TEXT("mmioAdvance"), E_FAIL );
        }

        *((BYTE*)m_mmioinfoOut.pchNext) = *((BYTE*)pbSrcData+cT);
        (BYTE*)m_mmioinfoOut.pchNext++;

        (*pnSizeWrote)++;
    }

    return S_OK;
}