misc/crcgen.c

   1 #include <inttypes.h>
   2 #include <stdio.h>
   3
   4 int main(int argc, char *argv[])
   5 {
   6     /* Polynomial in bit-reversed notation */
   7     uint64_t poly;
   8     uint64_t crctab[256], v;
   9     int i, j;
  10
  11     poly = strtoumax(argv[1], NULL, 0);
  12
  13     printf("/* C */\n");
  14     printf("static const uint64_t crc64_tab[256] = {\n");
  15     for (i = 0; i < 256; i++) {
  16         v = i;
  17         for (j = 0; j < 8; j++)
  18             v = (v >> 1) ^ ((v & 1) ? poly : 0);
  19         crctab[i] = v;
  20     }
  21
  22     for (i = 0; i < 256; i += 2) {
  23         printf("    /* %02x */ UINT64_C(0x%016"PRIx64"), "
  24                "UINT64_C(0x%016"PRIx64")%s\n",
  25                i, crctab[i], crctab[i+1], (i == 254) ? "" : ",");
  26     }
  27     printf("};\n\n");
  28
  29     printf("# perl\n");
  30     printf("@crc64_tab = (\n");
  31     for (i = 0; i < 256; i += 2) {
  32         printf("    [0x%08"PRIx32", 0x%08"PRIx32"], "
  33                "[0x%08"PRIx32", 0x%08"PRIx32"]%-1s    # %02x\n",
  34                (uint32_t)(crctab[i] >> 32),
  35                (uint32_t)(crctab[i]),
  36                (uint32_t)(crctab[i+1] >> 32),
  37                (uint32_t)(crctab[i+1]),
  38                (i == 254) ? "" : ",",
  39                i);
  40     }
  41     printf(");\n");
  42
  43     return 0;
  44 }