This function fills and empties the contents of an I/O buffer of a file set up for direct I/O buffer manipulation by mmioGetInfo.

#define INCL_MMIOOS2
#include <os2.h>

HMMIO        hmmio;      /*  Open file handle. */
PMMIOINFO    pmmioinfo;  /*  Pointer to MMIOINFO. */
USHORT       usFlags;    /*  Flags. */
USHORT       rc;         /*  Return codes. */

rc = mmioAdvance(hmmio, pmmioinfo, usFlags);