167 lines
3.3 KiB
C++
167 lines
3.3 KiB
C++
//-----------------------------------------------------------------------------
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// MurmurHash3 was written by Austin Appleby, and is placed in the public
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// domain. The author hereby disclaims copyright to this source code.
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// Note - The x86 and x64 versions do _not_ produce the same results, as the
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// algorithms are optimized for their respective platforms. You can still
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// compile and run any of them on any platform, but your performance with the
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// non-native version will be less than optimal.
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#include "murmur.h"
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#define FORCE_INLINE inline static
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FORCE_INLINE uint64_t rotl64(uint64_t x, int8_t r)
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{
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return (x << r) | (x >> (64 - r));
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}
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#define ROTL64(x, y) rotl64(x, y)
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#define BIG_CONSTANT(x) (x##LLU)
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#define getblock(x, i) (x[i])
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//-----------------------------------------------------------------------------
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// Finalization mix - force all bits of a hash block to avalanche
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FORCE_INLINE uint64_t fmix64(uint64_t k)
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{
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k ^= k >> 33;
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k *= BIG_CONSTANT(0xff51afd7ed558ccd);
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k ^= k >> 33;
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k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
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k ^= k >> 33;
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return k;
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}
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//-----------------------------------------------------------------------------
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void MurmurHash3_x64_128(const void *key, const int len, const uint32_t seed, void *out)
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{
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const uint8_t *data = (const uint8_t *)key;
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const int nblocks = len / 16;
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uint64_t h1 = seed;
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uint64_t h2 = seed;
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uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
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uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
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int i;
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//----------
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// body
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const uint64_t *blocks = (const uint64_t *)(data);
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for (i = 0; i < nblocks; i++)
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{
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uint64_t k1 = getblock(blocks, i * 2 + 0);
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uint64_t k2 = getblock(blocks, i * 2 + 1);
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k1 *= c1;
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k1 = ROTL64(k1, 31);
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k1 *= c2;
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h1 ^= k1;
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h1 = ROTL64(h1, 27);
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h1 += h2;
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h1 = h1 * 5 + 0x52dce729;
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k2 *= c2;
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k2 = ROTL64(k2, 33);
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k2 *= c1;
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h2 ^= k2;
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h2 = ROTL64(h2, 31);
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h2 += h1;
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h2 = h2 * 5 + 0x38495ab5;
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}
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//----------
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// tail
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const uint8_t *tail = (const uint8_t *)(data + nblocks * 16);
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uint64_t k1 = 0;
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uint64_t k2 = 0;
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switch (len & 15)
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{
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case 15:
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k2 ^= ((uint64_t)tail[14]) << 48;
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[[fallthrough]];
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case 14:
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k2 ^= ((uint64_t)tail[13]) << 40;
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[[fallthrough]];
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case 13:
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k2 ^= ((uint64_t)tail[12]) << 32;
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[[fallthrough]];
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case 12:
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k2 ^= ((uint64_t)tail[11]) << 24;
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[[fallthrough]];
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case 11:
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k2 ^= ((uint64_t)tail[10]) << 16;
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[[fallthrough]];
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case 10:
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k2 ^= ((uint64_t)tail[9]) << 8;
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[[fallthrough]];
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case 9:
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k2 ^= ((uint64_t)tail[8]) << 0;
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k2 *= c2;
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k2 = ROTL64(k2, 33);
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k2 *= c1;
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h2 ^= k2;
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[[fallthrough]];
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case 8:
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k1 ^= ((uint64_t)tail[7]) << 56;
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[[fallthrough]];
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case 7:
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k1 ^= ((uint64_t)tail[6]) << 48;
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[[fallthrough]];
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case 6:
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k1 ^= ((uint64_t)tail[5]) << 40;
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[[fallthrough]];
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case 5:
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k1 ^= ((uint64_t)tail[4]) << 32;
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[[fallthrough]];
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case 4:
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k1 ^= ((uint64_t)tail[3]) << 24;
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[[fallthrough]];
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case 3:
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k1 ^= ((uint64_t)tail[2]) << 16;
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[[fallthrough]];
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case 2:
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k1 ^= ((uint64_t)tail[1]) << 8;
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[[fallthrough]];
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case 1:
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k1 ^= ((uint64_t)tail[0]) << 0;
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k1 *= c1;
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k1 = ROTL64(k1, 31);
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k1 *= c2;
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h1 ^= k1;
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}
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//----------
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// finalization
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h1 ^= len;
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h2 ^= len;
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h1 += h2;
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h2 += h1;
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h1 = fmix64(h1);
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h2 = fmix64(h2);
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h1 += h2;
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h2 += h1;
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((uint64_t *)out)[0] = h1;
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((uint64_t *)out)[1] = h2;
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}
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//-----------------------------------------------------------------------------
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