apps/plugins/zxbox/compr.c

   1 /*
   2  * Copyright (C) 1996-1998 Szeredi Miklos
   3  * Email: mszeredi@inf.bme.hu
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version. See the file COPYING.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  *
  19  */
  20
  21 #include "compr.h"
  22
  23 void compr(void)
  24 {
  25   int j, c, lc, lled, rep, num;
  26
  27   rep = 0;
  28
  29   c = compr_read_byte();
  30   lc = 0;
  31   num = 0;
  32
  33   while(c >= 0) {
  34     if(lc == 0xED) lled = 1;
  35     else lled = 0;
  36
  37     lc = c;
  38     c = compr_read_byte();
  39     if(c == lc && num != 255 && (!lled || rep)) {
  40       if(!rep) {
  41     num = 1;
  42     rep = 1;
  43       }
  44       num++;
  45     }
  46     else {
  47       if(rep) {
  48     if(num < 5 && lc != 0xED) for(j = 0; j < num; j++) compr_put_byte(lc);
  49     else{
  50       compr_put_byte(0xED);
  51       compr_put_byte(0xED);
  52       compr_put_byte(num);
  53       compr_put_byte(lc);
  54       num = 0;
  55     }
  56     rep = 0;
  57       }
  58       else compr_put_byte(lc);
  59     }
  60   }
  61
  62   compr_put_byte(0x00);
  63   compr_put_byte(0xED);
  64   compr_put_byte(0xED);
  65   compr_put_byte(0x00);
  66 }
  67