2.9BSD - /usr/src/cmd/sum.c

   1: /*
   2:  * Sum bytes in file mod 2^16
   3:  */
   4: 
   5: #include <stdio.h>
   6: 
   7: main(argc,argv)
   8: char **argv;
   9: {
  10:     register unsigned sum;
  11:     register i, c;
  12:     register FILE *f;
  13:     register long nbytes;
  14:     int errflg = 0;
  15: 
  16:     i = 1;
  17:     do {
  18:         if(i < argc) {
  19:             if ((f = fopen(argv[i], "r")) == NULL) {
  20:                 fprintf(stderr, "sum: Can't open %s\n", argv[i]);
  21:                 errflg += 10;
  22:                 continue;
  23:             }
  24:         } else
  25:             f = stdin;
  26:         sum = 0;
  27:         nbytes = 0;
  28:         while ((c = getc(f)) != EOF) {
  29:             nbytes++;
  30:             if (sum&01)
  31:                 sum = (sum>>1) + 0x8000;
  32:             else
  33:                 sum >>= 1;
  34:             sum += c;
  35:             sum &= 0xFFFF;
  36:         }
  37:         if (ferror(f)) {
  38:             errflg++;
  39:             fprintf(stderr, "sum: read error on %s\n", argc>1?argv[i]:"-");
  40:         }
  41:         printf("%05u%6ld", sum, (nbytes+BUFSIZ-1)/BUFSIZ);
  42:         if(argc > 2)
  43:             printf(" %s", argv[i]);
  44:         printf("\n");
  45:         fclose(f);
  46:     } while(++i < argc);
  47:     exit(errflg);
  48: }

Defined functions