crc/fnv.c

   1 #include "fnv.h"
   2
   3 #define FNV_PRIME       0x100000001b3ULL
   4
   5 /*
   6  * 64-bit fnv, but don't require 64-bit multiples of data. Use bytes
   7  * for the last unaligned chunk.
   8  */
   9 uint64_t fnv(const void *buf, uint32_t len, uint64_t hval)
  10 {
  11         const uint64_t *ptr = buf;
  12
  13         while (len) {
  14                 hval *= FNV_PRIME;
  15                 if (len >= sizeof(uint64_t)) {
  16                         hval ^= (uint64_t) *ptr++;
  17                         len -= sizeof(uint64_t);
  18                         continue;
  19                 } else {
  20                         const uint8_t *ptr8 = (const uint8_t *) ptr;
  21                         uint64_t val = 0;
  22                         int i;
  23
  24                         for (i = 0; i < len; i++) {
  25                                 val <<= 8;
  26                                 val |= (uint8_t) *ptr8++;
  27                         }
  28                         hval ^= val;
  29                         break;
  30                 }
  31         }
  32
  33         return hval;
  34 }