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// SPDX-License-Identifier: LGPL-2.1+
/*
* MurmurHash3 was written by Austin Appleby, and is placed in the public
* domain. The author hereby disclaims copyright to this source code.
*
* Adapted by John Wiele (jwiele@redhat.com).
*/
#include "murmurhash3.h"
#include <linux/unaligned.h>
static inline u64 rotl64(u64 x, s8 r)
{
return (x << r) | (x >> (64 - r));
}
#define ROTL64(x, y) rotl64(x, y)
/* Finalization mix - force all bits of a hash block to avalanche */
static __always_inline u64 fmix64(u64 k)
{
k ^= k >> 33;
k *= 0xff51afd7ed558ccdLLU;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53LLU;
k ^= k >> 33;
return k;
}
void murmurhash3_128(const void *key, const int len, const u32 seed, void *out)
{
const u8 *data = key;
const int nblocks = len / 16;
u64 h1 = seed;
u64 h2 = seed;
const u64 c1 = 0x87c37b91114253d5LLU;
const u64 c2 = 0x4cf5ad432745937fLLU;
u64 *hash_out = out;
/* body */
const u64 *blocks = (const u64 *)(data);
int i;
for (i = 0; i < nblocks; i++) {
u64 k1 = get_unaligned_le64(&blocks[i * 2]);
u64 k2 = get_unaligned_le64(&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 u8 *tail = (const u8 *)(data + nblocks * 16);
u64 k1 = 0;
u64 k2 = 0;
switch (len & 15) {
case 15:
k2 ^= ((u64)tail[14]) << 48;
fallthrough;
case 14:
k2 ^= ((u64)tail[13]) << 40;
fallthrough;
case 13:
k2 ^= ((u64)tail[12]) << 32;
fallthrough;
case 12:
k2 ^= ((u64)tail[11]) << 24;
fallthrough;
case 11:
k2 ^= ((u64)tail[10]) << 16;
fallthrough;
case 10:
k2 ^= ((u64)tail[9]) << 8;
fallthrough;
case 9:
k2 ^= ((u64)tail[8]) << 0;
k2 *= c2;
k2 = ROTL64(k2, 33);
k2 *= c1;
h2 ^= k2;
fallthrough;
case 8:
k1 ^= ((u64)tail[7]) << 56;
fallthrough;
case 7:
k1 ^= ((u64)tail[6]) << 48;
fallthrough;
case 6:
k1 ^= ((u64)tail[5]) << 40;
fallthrough;
case 5:
k1 ^= ((u64)tail[4]) << 32;
fallthrough;
case 4:
k1 ^= ((u64)tail[3]) << 24;
fallthrough;
case 3:
k1 ^= ((u64)tail[2]) << 16;
fallthrough;
case 2:
k1 ^= ((u64)tail[1]) << 8;
fallthrough;
case 1:
k1 ^= ((u64)tail[0]) << 0;
k1 *= c1;
k1 = ROTL64(k1, 31);
k1 *= c2;
h1 ^= k1;
break;
default:
break;
}
}
/* finalization */
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
put_unaligned_le64(h1, &hash_out[0]);
put_unaligned_le64(h2, &hash_out[1]);
}
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