Blender  V3.3
hash_mm2a.c
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1 /* SPDX-License-Identifier: GPL-2.0-or-later
2  * Copyright 2014 Blender Foundation. */
3 
20 #include "BLI_compiler_attrs.h"
21 
22 #include "BLI_hash_mm2a.h" /* own include */
23 
24 /* Helpers. */
25 #define MM2A_M 0x5bd1e995
26 
27 #define MM2A_MIX(h, k) \
28  { \
29  (k) *= MM2A_M; \
30  (k) ^= (k) >> 24; \
31  (k) *= MM2A_M; \
32  (h) = ((h)*MM2A_M) ^ (k); \
33  } \
34  (void)0
35 
36 #define MM2A_MIX_FINALIZE(h) \
37  { \
38  (h) ^= (h) >> 13; \
39  (h) *= MM2A_M; \
40  (h) ^= (h) >> 15; \
41  } \
42  (void)0
43 
44 static void mm2a_mix_tail(BLI_HashMurmur2A *mm2, const unsigned char **data, size_t *len)
45 {
46  while (*len && ((*len < 4) || mm2->count)) {
47  mm2->tail |= (uint32_t)(**data) << (mm2->count * 8);
48 
49  mm2->count++;
50  (*len)--;
51  (*data)++;
52 
53  if (mm2->count == 4) {
54  MM2A_MIX(mm2->hash, mm2->tail);
55  mm2->tail = 0;
56  mm2->count = 0;
57  }
58  }
59 }
60 
62 {
63  mm2->hash = seed;
64  mm2->tail = 0;
65  mm2->count = 0;
66  mm2->size = 0;
67 }
68 
69 void BLI_hash_mm2a_add(BLI_HashMurmur2A *mm2, const unsigned char *data, size_t len)
70 {
71  mm2->size += (uint32_t)len;
72 
73  mm2a_mix_tail(mm2, &data, &len);
74 
75  for (; len >= 4; data += 4, len -= 4) {
76  uint32_t k = *(const uint32_t *)data;
77 
78  MM2A_MIX(mm2->hash, k);
79  }
80 
81  mm2a_mix_tail(mm2, &data, &len);
82 }
83 
85 {
86  BLI_hash_mm2a_add(mm2, (const unsigned char *)&data, sizeof(data));
87 }
88 
90 {
91  MM2A_MIX(mm2->hash, mm2->tail);
92  MM2A_MIX(mm2->hash, mm2->size);
93 
94  MM2A_MIX_FINALIZE(mm2->hash);
95 
96  return mm2->hash;
97 }
98 
99 uint32_t BLI_hash_mm2(const unsigned char *data, size_t len, uint32_t seed)
100 {
101  /* Initialize the hash to a 'random' value */
102  uint32_t h = seed ^ len;
103 
104  /* Mix 4 bytes at a time into the hash */
105  for (; len >= 4; data += 4, len -= 4) {
106  uint32_t k = *(uint32_t *)data;
107 
108  MM2A_MIX(h, k);
109  }
110 
111  /* Handle the last few bytes of the input array */
112  switch (len) {
113  case 3:
114  h ^= data[2] << 16;
116  case 2:
117  h ^= data[1] << 8;
119  case 1:
120  h ^= data[0];
121  h *= MM2A_M;
122  }
123 
124  /* Do a few final mixes of the hash to ensure the last few bytes are well-incorporated. */
126 
127  return h;
128 }
#define ATTR_FALLTHROUGH
static unsigned long seed
Definition: btSoftBody.h:39
int len
Definition: draw_manager.c:108
void BLI_hash_mm2a_init(BLI_HashMurmur2A *mm2, uint32_t seed)
Definition: hash_mm2a.c:61
static void mm2a_mix_tail(BLI_HashMurmur2A *mm2, const unsigned char **data, size_t *len)
Definition: hash_mm2a.c:44
void BLI_hash_mm2a_add(BLI_HashMurmur2A *mm2, const unsigned char *data, size_t len)
Definition: hash_mm2a.c:69
void BLI_hash_mm2a_add_int(BLI_HashMurmur2A *mm2, int data)
Definition: hash_mm2a.c:84
uint32_t BLI_hash_mm2a_end(BLI_HashMurmur2A *mm2)
Definition: hash_mm2a.c:89
#define MM2A_MIX_FINALIZE(h)
Definition: hash_mm2a.c:36
#define MM2A_M
Definition: hash_mm2a.c:25
#define MM2A_MIX(h, k)
Definition: hash_mm2a.c:27
uint32_t BLI_hash_mm2(const unsigned char *data, size_t len, uint32_t seed)
Definition: hash_mm2a.c:99
unsigned int uint32_t
Definition: stdint.h:80