The mmioDescend function descends into a chunk or searches for a chunk, beginning at the current file position. The mmioDescend function requires a pckinfo parameter, which specifies a pointer to a MMCKINFO structure that mmioDescend fills with information on the current chunk. You can also specify the pckinfoParent parameter, which specifies an optional caller-supplied structure that refers to the parent of the chunk that is being searched for. If there is no parent chunk, set pckinfoParent to NULL.
The usFlags parameter specifies options for searching for a chunk. Choose from the following options:
┌─────────────────┬───────────────────────────────────┐ │Flag │Description │ ├─────────────────┼───────────────────────────────────┤ │MMIO_FINDCHUNK │Searches for a chunk with a │ │ │specific chunk ID. The ckid field │ │ │pckinfo should contain the chunk ID│ │ │of the chunk to search for when │ │ │mmioDescend is called. │ ├─────────────────┼───────────────────────────────────┤ │MMIO_FINDRIFF │Searches for a chunk with a RIFF │ │ │chunk ID and with a specific form │ │ │type. The fccType field of pckinfo│ │ │should contain the form type of the│ │ │RIFF chunk to search for when │ │ │mmioDescend is called. │ ├─────────────────┼───────────────────────────────────┤ │MMIO_FINDLIST │Searches for a chunk with a chunk │ │ │ID of LIST and with a specific list│ │ │type. The fccType field of pckinfo│ │ │should contain the list type of the│ │ │LIST chunk to search for when │ │ │mmioDescend is called. │ └─────────────────┴───────────────────────────────────┘
Note: If you do not specify any flags, mmioDescend descends into the chunk that starts at the current file position.
The mmioDescend function fills an MMCKINFO structure with information on the chunk. This information includes the chunk ID (ckid), the size of the data field (ckSize), and the form type, or list type, depending on whether the chunk is a RIFF or LIST chunk. The mmioDescend function assumes that the current file position is the beginning of a chunk header when mmioDescend is called. If pckinfoParent is given, mmioDescend assumes that the current file position is within pckinfoParent (a RIFF or LIST chunk).