Searching for a Subchunk

The following example uses the mmioDescend52B.0WE function to search for the  FMT  chunk in the  RIFF  chunk of the previous example.

// Find the format chunk (form type "FMT"); it should be

// a subchunk of the "RIFF" parent chunk.

mmckinfoSubchunk.ckid = mmioFOURCC('f', 'm', 't', ' ');

if (mmioDescend(hmmio, &mmckinfoSubchunk, &mmckinfoParent,

    MMIO_FINDCHUNK))

    // Error, cannot find the "FMT" chunk.

else

    // "FMT" chunk found.

To search for a subchunk (that is, any chunk other than a  RIFF  or  LIST  chunk), identify its parent chunk in the lpckParent parameter of the mmioDescend52B.0WE function.

If you do not specify a parent chunk, the current file position should be at the beginning of a chunk before you call the mmioDescend function. If you do specify a parent chunk, the current file position can be anywhere in that chunk.

If the search for a subchunk fails, the current file position is undefined. You can use the mmioSeek205J4W5 function and the dwDataOffset member of the MMCKINFO2NZM4LP structure describing the parent chunk to seek back to the beginning of the parent chunk, as in the following example:

mmioSeek(hmmio, mmckinfoParent.dwDataOffset + 4, SEEK_SET);

Because dwDataOffset specifies the offset to the beginning of the data portion of the chunk, you must seek 4 bytes past dwDataOffset to set the file position after the form type.