commands/crc/crc.c

   1 /* Compute checksum                     Author: Johan W. Stevenson */
   2
   3 /* Copyright 1988 by Johan W. Stevenson */
   4
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <stdio.h>
   8 #include <string.h>
   9 #include <errno.h>
  10
  11 int errs;
  12
  13 #if __STDC__
  14 int main(int argc, char **argv);
  15 void crc(char *fname);
  16 #else
  17 void crc();
  18 #endif
  19
  20 int main(argc, argv)
  21 int argc;
  22 char **argv;
  23 {
  24   char line[256];
  25
  26   if (argc <= 1)
  27         crc((char *) 0);
  28   else if (argc == 2 && strcmp(argv[1], "-") == 0)
  29         while (fgets(line, sizeof line, stdin) != NULL) {
  30                 if (line[strlen(line) - 1] == '\n')
  31                         line[strlen(line) - 1] = '\0';
  32                 crc(line);
  33         }
  34   else
  35         do {
  36                 crc(argv[1]);
  37                 argv++;
  38                 argc--;
  39         } while (argc > 1);
  40   return(errs != 0);
  41 }
  42
  43 /* Crctab calculated by Mark G. Mendel, Network Systems Corporation */
  44 static unsigned short crctab[256] = {
  45        0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
  46        0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
  47        0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
  48        0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
  49        0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
  50        0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
  51        0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
  52        0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
  53        0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
  54        0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
  55        0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
  56        0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
  57        0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
  58        0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
  59        0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
  60        0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
  61        0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
  62        0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
  63        0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
  64        0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
  65        0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
  66        0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
  67        0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
  68        0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
  69        0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
  70        0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
  71        0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
  72        0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
  73        0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
  74        0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
  75        0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
  76         0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
  77 };
  78
  79 /* Updcrc macro derived from article Copyright (C) 1986 Stephen Satchell.
  80  *  NOTE: First argument must be in range 0 to 255.
  81  *        Second argument is referenced twice.
  82  *
  83  * Programmers may incorporate any or all code into their programs,
  84  * giving proper credit within the source. Publication of the
  85  * source routines is permitted so long as proper credit is given
  86  * to Stephen Satchell, Satchell Evaluations and Chuck Forsberg,
  87  * Omen Technology.
  88  */
  89
  90 #define updcrc(cp, crc) ( crctab[((crc >> 8) & 255)] ^ (crc << 8) ^ cp)
  91
  92 void crc(fname)
  93 char *fname;
  94 {
  95   register int c;
  96   register long len = 0;
  97   register unsigned short crc = 0;
  98   register FILE *fp;
  99
 100   if (fname == NULL)
 101         fp = stdin;
 102   else if ((fp = fopen(fname, "r")) == NULL) {
 103         fprintf(stderr, "crc: Can't open %s: %s\n", fname, strerror(errno));
 104         errs++;
 105         return;
 106   }
 107   while ((c = getc(fp)) != EOF) {
 108         len++;
 109         crc = updcrc(c, crc);
 110   }
 111   printf("%05u %6ld", crc, len);
 112   if (fname) {
 113         printf(" %s", fname);
 114         fclose(fp);
 115   }
 116   printf("\n");
 117 }