ruby-tdb.git  about / heads / tags
Trivial Database bindings for Ruby
blob e8fc030f099117fad81991483c91b903336cff15 4325 bytes (raw)
$ git show HEAD:ext/tdb/murmur3.c	# shows this blob on the CLI

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
 
#include "rbtdb.h"
/*
 * https://sites.google.com/site/murmurhash/
 *
 * MurmurHash3 was written by Austin Appleby, and is placed in the public
 * domain. The author hereby disclaims copyright to this source code.
 *
 * Eric Wong trivially ported this to C for Ruby tdb (32-bit versions only)
 */

#include <stdint.h>

static inline uint32_t rotl32(uint32_t x, int8_t r)
{
	return (x << r) | (x >> (32 - r));
}

#define	ROTL32(x,y)	rotl32(x,y)

#define BIG_CONSTANT(x) (x##LLU)

/* ----------------------------------------------------------------------------
 * Block read - if your platform needs to do endian-swapping or can only
 * handle aligned reads, do the conversion here
 */

static inline uint32_t getblock(const uint32_t * p, int i)
{
	return p[i];
}

/* ----------------------------------------------------------------------------
 * Finalization mix - force all bits of a hash block to avalanche
 */

static inline uint32_t fmix(uint32_t h)
{
	h ^= h >> 16;
	h *= 0x85ebca6b;
	h ^= h >> 13;
	h *= 0xc2b2ae35;
	h ^= h >> 16;

	return h;
}

unsigned int rbtdb_murmur3a(TDB_DATA * key)
{
	const uint8_t *data = key->dptr;
	int len = (int)key->dsize;
	const int nblocks = len / 4;
	static const uint32_t seed;
	uint32_t h1 = seed;
	int i;

	static const uint32_t c1 = 0xcc9e2d51;
	static const uint32_t c2 = 0x1b873593;

	/* body */
	const uint32_t *blocks = (const uint32_t *)(data + nblocks * 4);

	for (i = -nblocks; i; i++) {
		uint32_t k1 = getblock(blocks, i);

		k1 *= c1;
		k1 = ROTL32(k1, 15);
		k1 *= c2;

		h1 ^= k1;
		h1 = ROTL32(h1, 13);
		h1 = h1 * 5 + 0xe6546b64;
	}

	/* tail */
	{
		const uint8_t *tail = (const uint8_t *)(data + nblocks * 4);
		uint32_t k1 = 0;

		switch (len & 3) {
		case 3:
			k1 ^= tail[2] << 16;
		case 2:
			k1 ^= tail[1] << 8;
		case 1:
			k1 ^= tail[0];
			k1 *= c1;
			k1 = ROTL32(k1, 15);
			k1 *= c2;
			h1 ^= k1;
		};
	}

	/* finalization */

	h1 ^= len;

	return fmix(h1);
}

static inline uint64_t rotl64(uint64_t x, int8_t r)
{
	return (x << r) | (x >> (64 - r));
}

#define ROTL64(x,y)	rotl64(x,y)

static inline uint64_t getblock64(const uint64_t * p, int i)
{
	return p[i];
}

static inline uint64_t fmix64(uint64_t k)
{
	k ^= k >> 33;
	k *= BIG_CONSTANT(0xff51afd7ed558ccd);
	k ^= k >> 33;
	k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
	k ^= k >> 33;

	return k;
}

/* this was a 128-bit hash for x86_64, but we only want 32-bits */
unsigned int rbtdb_murmur3f(TDB_DATA * key)
{
	const uint8_t *data = key->dptr;
	int len = (int)key->dsize;
	const int nblocks = len / 16;
	static const uint32_t seed;
	uint64_t h1 = seed;
	uint64_t h2 = seed;
	uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
	uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
	int i;

	/* body */
	const uint64_t *blocks = (const uint64_t *)(data);

	for (i = 0; i < nblocks; i++) {
		uint64_t k1 = getblock64(blocks, i * 2 + 0);
		uint64_t k2 = getblock64(blocks, i * 2 + 1);

		k1 *= c1;
		k1 = ROTL64(k1, 31);
		k1 *= c2;
		h1 ^= k1;

		h1 = ROTL64(h1, 27);
		h1 += h2;
		h1 = h1 * 5 + 0x52dce729;

		k2 *= c2;
		k2 = ROTL64(k2, 33);
		k2 *= c1;
		h2 ^= k2;

		h2 = ROTL64(h2, 31);
		h2 += h1;
		h2 = h2 * 5 + 0x38495ab5;
	}

	/* tail */
	{
		const uint8_t *tail = (const uint8_t *)(data + nblocks * 16);

		uint64_t k1 = 0;
		uint64_t k2 = 0;
		#define CAST64(x) ((uint64_t)(x))

		switch (len & 15) {
		case 15:
			k2 ^= CAST64(tail[14]) << 48;
		case 14:
			k2 ^= CAST64(tail[13]) << 40;
		case 13:
			k2 ^= CAST64(tail[12]) << 32;
		case 12:
			k2 ^= CAST64(tail[11]) << 24;
		case 11:
			k2 ^= CAST64(tail[10]) << 16;
		case 10:
			k2 ^= CAST64(tail[9]) << 8;
		case 9:
			k2 ^= CAST64(tail[8]) << 0;
			k2 *= c2;
			k2 = ROTL64(k2, 33);
			k2 *= c1;
			h2 ^= k2;

		case 8:
			k1 ^= CAST64(tail[7]) << 56;
		case 7:
			k1 ^= CAST64(tail[6]) << 48;
		case 6:
			k1 ^= CAST64(tail[5]) << 40;
		case 5:
			k1 ^= CAST64(tail[4]) << 32;
		case 4:
			k1 ^= CAST64(tail[3]) << 24;
		case 3:
			k1 ^= CAST64(tail[2]) << 16;
		case 2:
			k1 ^= CAST64(tail[1]) << 8;
		case 1:
			k1 ^= CAST64(tail[0]) << 0;
			k1 *= c1;
			k1 = ROTL64(k1, 31);
			k1 *= c2;
			h1 ^= k1;
		};
	}

	/* finalization */

	h1 ^= len;
	h2 ^= len;

	h1 += h2;
	h2 += h1;

	h1 = fmix64(h1);
	h2 = fmix64(h2);

	h1 += h2;

	/* not needed for 32-bit hash */
	/* h2 += h1; */

	return (unsigned int)h1; /* truncate to 32-bits */
}

git clone https://yhbt.net/ruby-tdb.git