source/modules/lilv/sord-0.16.0/src/zix/digest.c

   1 /*
   2   Copyright 2012-2014 David Robillard <http://drobilla.net>
   3
   4   Permission to use, copy, modify, and/or distribute this software for any
   5   purpose with or without fee is hereby granted, provided that the above
   6   copyright notice and this permission notice appear in all copies.
   7
   8   THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 */
  16
  17 #include "zix/digest.h"
  18
  19 #ifdef __SSE4_2__
  20 #    include <smmintrin.h>
  21 #endif
  22
  23 ZIX_API uint32_t
  24 zix_digest_start(void)
  25 {
  26 #ifdef __SSE4_2__
  27         return 1;  // CRC32 initial value
  28 #else
  29         return 5381;  // DJB hash initial value
  30 #endif
  31 }
  32
  33 ZIX_API uint32_t
  34 zix_digest_add(uint32_t hash, const void* const buf, const size_t len)
  35 {
  36         const uint8_t* str = (const uint8_t*)buf;
  37 #ifdef __SSE4_2__
  38         // SSE 4.2 CRC32
  39         for (size_t i = 0; i < (len / sizeof(uint32_t)); ++i) {
  40                 hash = _mm_crc32_u32(hash, *(const uint32_t*)str);
  41                 str += sizeof(uint32_t);
  42         }
  43         if (len & sizeof(uint16_t)) {
  44                 hash = _mm_crc32_u16(hash, *(const uint16_t*)str);
  45                 str += sizeof(uint16_t);
  46         }
  47         if (len & sizeof(uint8_t)) {
  48                 hash = _mm_crc32_u8(hash, *(const uint8_t*)str);
  49         }
  50 #else
  51         // Classic DJB hash
  52         for (size_t i = 0; i < len; ++i) {
  53                 hash = (hash << 5) + hash + str[i];
  54         }
  55 #endif
  56         return hash;
  57 }