159 lines
2.6 KiB
C
159 lines
2.6 KiB
C
// SPDX-License-Identifier: LGPL-2.1+
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/*
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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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*
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* Adapted by John Wiele (jwiele@redhat.com).
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*/
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#include "murmurhash3.h"
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#include <asm/unaligned.h>
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static inline u64 rotl64(u64 x, s8 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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/* Finalization mix - force all bits of a hash block to avalanche */
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static __always_inline u64 fmix64(u64 k)
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{
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k ^= k >> 33;
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k *= 0xff51afd7ed558ccdLLU;
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k ^= k >> 33;
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k *= 0xc4ceb9fe1a85ec53LLU;
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k ^= k >> 33;
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return k;
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}
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void murmurhash3_128(const void *key, const int len, const u32 seed, void *out)
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{
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const u8 *data = key;
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const int nblocks = len / 16;
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u64 h1 = seed;
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u64 h2 = seed;
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const u64 c1 = 0x87c37b91114253d5LLU;
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const u64 c2 = 0x4cf5ad432745937fLLU;
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u64 *hash_out = out;
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/* body */
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const u64 *blocks = (const u64 *)(data);
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int i;
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for (i = 0; i < nblocks; i++) {
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u64 k1 = get_unaligned_le64(&blocks[i * 2]);
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u64 k2 = get_unaligned_le64(&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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/* tail */
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{
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const u8 *tail = (const u8 *)(data + nblocks * 16);
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u64 k1 = 0;
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u64 k2 = 0;
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switch (len & 15) {
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case 15:
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k2 ^= ((u64)tail[14]) << 48;
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fallthrough;
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case 14:
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k2 ^= ((u64)tail[13]) << 40;
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fallthrough;
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case 13:
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k2 ^= ((u64)tail[12]) << 32;
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fallthrough;
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case 12:
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k2 ^= ((u64)tail[11]) << 24;
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fallthrough;
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case 11:
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k2 ^= ((u64)tail[10]) << 16;
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fallthrough;
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case 10:
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k2 ^= ((u64)tail[9]) << 8;
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fallthrough;
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case 9:
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k2 ^= ((u64)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 ^= ((u64)tail[7]) << 56;
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fallthrough;
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case 7:
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k1 ^= ((u64)tail[6]) << 48;
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fallthrough;
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case 6:
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k1 ^= ((u64)tail[5]) << 40;
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fallthrough;
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case 5:
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k1 ^= ((u64)tail[4]) << 32;
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fallthrough;
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case 4:
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k1 ^= ((u64)tail[3]) << 24;
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fallthrough;
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case 3:
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k1 ^= ((u64)tail[2]) << 16;
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fallthrough;
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case 2:
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k1 ^= ((u64)tail[1]) << 8;
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fallthrough;
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case 1:
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k1 ^= ((u64)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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break;
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default:
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break;
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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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put_unaligned_le64(h1, &hash_out[0]);
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put_unaligned_le64(h2, &hash_out[1]);
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}
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