workbench/libs/asyncio/src/ReadCharAsync.c

   1 #include "async.h"
   2
   3
   4 _CALL LONG
   5 ReadCharAsync( _REG( a0 ) AsyncFile *file )
   6 {
   7         UBYTE   ch;
   8
   9         if( file->af_BytesLeft )
  10         {
  11                 /* if there is at least a byte left in the current buffer, get it
  12                  * directly. Also update all counters
  13                  */
  14
  15                 ch = *file->af_Offset;
  16                 --file->af_BytesLeft;
  17                 ++file->af_Offset;
  18
  19                 return( ( LONG ) ch );
  20         }
  21
  22         /* there were no characters in the current buffer, so call the main read
  23          * routine. This has the effect of sending a request to the file system to
  24          * have the current buffer refilled. After that request is done, the
  25          * character is extracted for the alternate buffer, which at that point
  26          * becomes the "current" buffer
  27          */
  28
  29         if( ReadAsync( file, &ch, 1 ) > 0 )
  30         {
  31                 return( ( LONG ) ch );
  32         }
  33
  34         /* We couldn't read above, so fail */
  35
  36         return( -1 );
  37 }