The following code illustrates how to read from a file.

   HMMIO hmmio1;
   PCHAR pchBuffer;
   LONG  cBytes;
   LONG  lBytesRead;
    ...

   lBytesRead = mmioRead(hmmio1, pchBuffer, cBytes);

   if (lBytesRead < 0L)
     /* error */
   else
    ...