From: wavemist AT ix DOT netcom DOT com
Newsgroups: comp.os.msdos.djgpp
Subject: Allegro Bitmap Question 2
Date: Sun, 02 Aug 1998 15:49:11 GMT
Organization: ICGNetcom
Lines: 129
Message-ID: <35c48784.1351913@nntp.ix.netcom.com>
NNTP-Posting-Host: prv-ri2-01.ix.netcom.com
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

Argh!  Ok, so I've learned that an 8 pixel by 8 pixel bitmap takes up
64 bytes in memory...great.  Yet for some reason, even if I feed two
identical tiles into memcmp, it claims that they are different.  Could
someone please look at the following code and tell me what I'm doing
wrong?  This is a program for ripping unique 8 by 8 tiles from a pcx
file.

/**************************** main ********************************/

void main(int argc, char *argv[])
{
   register int i;
   allegro_init();

   /* check that an input file was specified                      */
   if (argc < 2)
   {
      printf("Command syntax is: RIPPER infile1 <infile2>...\n");
      exit(1);
   }

   /* initialize some globals                                     */
   tile_index = 0;
   level_index = 0;
   x2 = y2 = 0;

   tile_storage = create_bitmap(320, 240);
   clear(tile_storage);

   pcx_file = create_bitmap(320, 240);
   clear(pcx_file);

   fresh_tile = create_bitmap(8, 8);
   clear(fresh_tile);

   /* set all the tiles in the level map to 490                   */
   for (i = 0; i < MAXTILES; i++)
       level_map[i] = 490;

   /* rip all the files specified on the command line             */
   for (i = 1; i <= argc; i++)
     rip(argv[i]); 

   /* write the level data and tiles out to disk                  */
   write_level();

   /* check your work -- reconstruct the pictures from the tiles  */
   display_level();

   /* restore the text video mode and exit                        */
   set_gfx_mode(GFX_TEXT, 24, 80, 0, 0);
   allegro_exit();
   exit(0);
}

/***************************** rip ********************************/

int rip(char *filename)
{
   unsigned int i,n;   
   int x,y;
   int status;

   /* if you already have a full screen tiles, return an error    */
   if (tile_index >= TILELIMIT) 
      return(-1);

   /* get  the PCX file       */
   pcx_file = load_pcx(filename, desktop_palette);
   
   x = 0;
   y = 0;

   /* loop on the pcx file, starting at upper left corner, moving
      down the columns in sequence                                */
   for (n = 0; n < TILELIMIT; n++)
   { 

      /* get the new tile bitmap                                  */
      blit(pcx_file, fresh_tile, x, y, 0, 0, 8, 8);

      /* compare the new tile to all the ripper tiles             */
      for (i = 0; i < tile_index; i++)
      {

         status = memcmp(fresh_tile, stored_tile[i], 64);

         if(status == 0)
            {
               /* a duplicate tile is found, update the level map
*/
               level_map[level_index] = i;             
               break;
            }
      }

      /* no match was found, therefore the tile must be unique    */
      if (level_map[level_index] == 490)
      {
         /* hold the array in RAM for later comparisons           */
         stored_tile[i] = create_bitmap(8, 8);
         clear(stored_tile[i]);

         blit(fresh_tile, stored_tile[i], 0, 0, 0, 0, 8, 8);

         /* build the level map with the tile index               */
         level_map[level_index] = tile_index;

         /* we can't have more than 480 unique tiles              */
         tile_index++;
         if (tile_index >= TILELIMIT)
            break;
      }

      y = y + 8;

      if(y > 240)
      {
          y = 0;
          x = x + 8;
      }

      level_index++;
   }

   return (0);
}