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48 lines
781 B
48 lines
781 B
/* |
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* Copyright (c) 2022, Meta |
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* |
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* SPDX-License-Identifier: Apache-2.0 |
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*/ |
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#include <stddef.h> |
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#include <stdint.h> |
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static inline uint32_t murmur_32_scramble(uint32_t k) |
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{ |
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k *= 0xcc9e2d51; |
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k = (k << 15) | (k >> 17); |
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k *= 0x1b873593; |
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return k; |
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} |
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uint32_t sys_hash32_murmur3(const char *str, size_t n) |
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{ |
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uint32_t k; |
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/* seed of 0 */ |
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uint32_t h = 0; |
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const size_t len = n; |
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for (; n >= sizeof(uint32_t); n -= sizeof(uint32_t), str += sizeof(uint32_t)) { |
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k = *(const uint32_t *)str; |
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h ^= murmur_32_scramble(k); |
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h = (h << 13) | (h >> 19); |
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h = h * 5 + 0xe6546b64; |
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} |
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for (k = 0; n != 0; --n, ++str) { |
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k <<= 8; |
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k |= *str; |
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} |
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h ^= murmur_32_scramble(k); |
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h ^= len; |
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h ^= h >> 16; |
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h *= 0x85ebca6b; |
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h ^= h >> 13; |
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h *= 0xc2b2ae35; |
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h ^= h >> 16; |
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return h; |
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}
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