/*
  * Copyright (C) 2013 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 #include <stdint.h>
 #include "mem.h"
 #include "intreadwrite.h"
 #include "murmur3.h"
 
 typedef struct AVMurMur3 {
     uint64_t h1, h2;
     uint8_t state[16];
     int state_pos;
     uint64_t len;
 } AVMurMur3;
 
 AVMurMur3 *av_murmur3_alloc(void)
 {
     return av_mallocz(sizeof(AVMurMur3));
 }
 
 void av_murmur3_init_seeded(AVMurMur3 *c, uint64_t seed)
 {
     memset(c, 0, sizeof(*c));
     c->h1 = c->h2 = seed;
 }
 
 void av_murmur3_init(AVMurMur3 *c)
 {
     // arbitrary random number as seed
     av_murmur3_init_seeded(c, 0x725acc55daddca55);
 }
 
 static const uint64_t c1 = UINT64_C(0x87c37b91114253d5);
 static const uint64_t c2 = UINT64_C(0x4cf5ad432745937f);
 

 #define ROT(a, b) (((a) << (b)) | ((a) >> (64 - (b))))

 
 static uint64_t inline get_k1(const uint8_t *src)
 {
     uint64_t k = AV_RL64(src);
     k *= c1;
     k = ROT(k, 31);
     k *= c2;
     return k;
 }
 
 static uint64_t inline get_k2(const uint8_t *src)
 {
     uint64_t k = AV_RL64(src + 8);
     k *= c2;
     k = ROT(k, 33);
     k *= c1;
     return k;
 }
 
 static uint64_t inline update_h1(uint64_t k, uint64_t h1, uint64_t h2)
 {
     k ^= h1;
     k = ROT(k, 27);
     k += h2;
     k *= 5;
     k += 0x52dce729;
     return k;
 }
 
 static uint64_t inline update_h2(uint64_t k, uint64_t h1, uint64_t h2)
 {
     k ^= h2;
     k = ROT(k, 31);
     k += h1;
     k *= 5;
     k += 0x38495ab5;
     return k;
 }
 
 void av_murmur3_update(AVMurMur3 *c, const uint8_t *src, int len)
 {
     const uint8_t *end;
     uint64_t h1 = c->h1, h2 = c->h2;
     uint64_t k1, k2;
     if (len <= 0) return;
     c->len += len;
     if (c->state_pos > 0) {
         while (c->state_pos < 16) {
             c->state[c->state_pos++] = *src++;
             if (--len <= 0) return;
         }
         c->state_pos = 0;
         k1 = get_k1(c->state);
         k2 = get_k2(c->state);
         h1 = update_h1(k1, h1, h2);
         h2 = update_h2(k2, h1, h2);
     }
 
     end = src + (len & ~15);
     while (src < end) {
         // These could be done sequentially instead
         // of interleaved, but like this is over 10% faster
         k1 = get_k1(src);
         k2 = get_k2(src);
         h1 = update_h1(k1, h1, h2);
         h2 = update_h2(k2, h1, h2);
         src += 16;
     }
     c->h1 = h1;
     c->h2 = h2;
 
     len &= 15;
     if (len > 0) {
         memcpy(c->state, src, len);
         c->state_pos = len;
     }
 }
 
 static inline uint64_t fmix(uint64_t k)
 {
     k ^= k >> 33;
     k *= UINT64_C(0xff51afd7ed558ccd);
     k ^= k >> 33;
     k *= UINT64_C(0xc4ceb9fe1a85ec53);
     k ^= k >> 33;
     return k;
 }
 
 void av_murmur3_final(AVMurMur3 *c, uint8_t dst[16])
 {
     uint64_t h1 = c->h1, h2 = c->h2;
     memset(c->state + c->state_pos, 0, sizeof(c->state) - c->state_pos);
     h1 ^= get_k1(c->state) ^ c->len;
     h2 ^= get_k2(c->state) ^ c->len;
     h1 += h2;
     h2 += h1;
     h1 = fmix(h1);
     h2 = fmix(h2);
     h1 += h2;
     h2 += h1;
     AV_WL64(dst, h1);
     AV_WL64(dst + 8, h2);
 }