TOOLS/compare.c

   1 /*
   2  * Simple file compare program, it finds the number of rounding errors
   3  * and dies if there is too large an error ( ABS(a-b)>1 ).
   4  *
   5  * copyright (c) 2001 Michael Niedermayer
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20  */
  21
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24
  25 // FIXME: No checks but it is just for debugging so who cares ;)
  26
  27 int main(int argc, char **argv)
  28 {
  29         FILE *f0, *f1;
  30         int dif=0;
  31
  32         if(argc!=3)
  33         {
  34                 printf("compare <file1> <file2>\n");
  35                 exit(2);
  36         }
  37
  38         f0= fopen(argv[1], "rb");
  39         f1= fopen(argv[2], "rb");
  40
  41         for(;;)
  42         {
  43                 short c0;
  44                 short c1;
  45                 int d;
  46
  47                 int e0= fread(&c0, 2, 1, f0);
  48                 int e1= fread(&c1, 2, 1, f1);
  49
  50                 d=c0-c1;
  51                 if(e0==0 && e1==0) break;
  52                 if(e0==0 || e1==0)
  53                 {
  54                         printf("FATAL error, files have different size!\n");
  55                         exit(1);
  56                 }
  57
  58                 if(d<0) d=-d; // ABS
  59                 if(d>1)
  60                 {
  61                         printf("FATAL error, too large a difference found (%d)!\n", d);
  62                         exit(1);
  63                 }
  64
  65                 if(d) dif++;
  66         }
  67
  68         fclose(f0);
  69         fclose(f1);
  70
  71         printf("%d (+/-1)differences found\n", dif);
  72         exit(0);
  73 }