The following code illustrates how to update open file information.

   HMMIO hmmio1;
   MMIOINFO mmioinfo;
   USHORT usFlags = 0;
   USHORT rc;
    ...

   memset( &mmioinfo, '\0', sizeof(MMIOINFO) );
   rc = mmioGetInfo( hmmio1, &mmioinfo, usFlags);
   if (rc)
     /* error */
   else
     /* do some low-level I/O */
    ...

   rc = mmioSetInfo( hmmio1, &mmioinfo, usFlags);

   if (rc)
     /* error */
   else
    ...