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//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.
// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.
#if defined(_MSC_VER)
#define ROTL32(x,y) _rotl(x,y)
#define ROTL64(x,y) _rotl64(x,y)
#else
gb_inline u32 rotl32(u32 x, i8 r) {
return (x << r) | (x >> (32-r));
}
gb_inline u64 rotl64(u64 x, i8 r) {
return (x << r) | (x >> (64-r));
}
#define ROTL32(x,y) rotl32(x,y)
#define ROTL64(x,y) rotl64(x,y)
#endif
gb_inline u32 fmix32(u32 h) {
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
gb_inline u64 fmix64(u64 k) {
k ^= k >> 33;
k *= 0xff51afd7ed558ccdULL;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53ULL;
k ^= k >> 33;
return k;
}
gb_inline u32 mm3_getblock32(u32 const *p, isize i) {
return p[i];
}
gb_inline u64 mm3_getblock64(u64 const *p, isize i) {
return p[i];
}
void MurmurHash3_x64_128(void const *key, isize len, u32 seed, void *out) {
u8 const * data = cast(u8 const *)key;
isize nblocks = len / 16;
u64 h1 = seed;
u64 h2 = seed;
u64 const c1 = 0x87c37b91114253d5ULL;
u64 const c2 = 0x4cf5ad432745937fULL;
u64 const * blocks = cast(u64 const *)data;
for (isize i = 0; i < nblocks; i++) {
u64 k1 = mm3_getblock64(blocks, i*2 + 0);
u64 k2 = mm3_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;
}
u8 const * tail = cast(u8 const *)(data + nblocks*16);
u64 k1 = 0;
u64 k2 = 0;
switch(len & 15) {
case 15: k2 ^= ((u64)tail[14]) << 48;
case 14: k2 ^= ((u64)tail[13]) << 40;
case 13: k2 ^= ((u64)tail[12]) << 32;
case 12: k2 ^= ((u64)tail[11]) << 24;
case 11: k2 ^= ((u64)tail[10]) << 16;
case 10: k2 ^= ((u64)tail[ 9]) << 8;
case 9: k2 ^= ((u64)tail[ 8]) << 0;
k2 *= c2; k2 = ROTL64(k2,33); k2 *= c1; h2 ^= k2;
case 8: k1 ^= ((u64)tail[ 7]) << 56;
case 7: k1 ^= ((u64)tail[ 6]) << 48;
case 6: k1 ^= ((u64)tail[ 5]) << 40;
case 5: k1 ^= ((u64)tail[ 4]) << 32;
case 4: k1 ^= ((u64)tail[ 3]) << 24;
case 3: k1 ^= ((u64)tail[ 2]) << 16;
case 2: k1 ^= ((u64)tail[ 1]) << 8;
case 1: k1 ^= ((u64)tail[ 0]) << 0;
k1 *= c1; k1 = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
}
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
((u64 *)out)[0] = h1;
((u64 *)out)[1] = h2;
}
void MurmurHash3_x86_128(void const *key, isize len, u32 seed, void *out) {
u8 const * data = cast(u8 * const)key;
isize nblocks = len / 16;
u32 h1 = seed;
u32 h2 = seed;
u32 h3 = seed;
u32 h4 = seed;
u32 const c1 = 0x239b961b;
u32 const c2 = 0xab0e9789;
u32 const c3 = 0x38b34ae5;
u32 const c4 = 0xa1e38b93;
//----------
// body
u32 const * blocks = cast(u32 const *)(data + nblocks*16);
for (isize i = -nblocks; i != 0; i++) {
u32 k1 = mm3_getblock32(blocks, i*4 + 0);
u32 k2 = mm3_getblock32(blocks, i*4 + 1);
u32 k3 = mm3_getblock32(blocks, i*4 + 2);
u32 k4 = mm3_getblock32(blocks, i*4 + 3);
k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
h1 = ROTL32(h1,19); h1 += h2; h1 = h1*5+0x561ccd1b;
k2 *= c2; k2 = ROTL32(k2,16); k2 *= c3; h2 ^= k2;
h2 = ROTL32(h2,17); h2 += h3; h2 = h2*5+0x0bcaa747;
k3 *= c3; k3 = ROTL32(k3,17); k3 *= c4; h3 ^= k3;
h3 = ROTL32(h3,15); h3 += h4; h3 = h3*5+0x96cd1c35;
k4 *= c4; k4 = ROTL32(k4,18); k4 *= c1; h4 ^= k4;
h4 = ROTL32(h4,13); h4 += h1; h4 = h4*5+0x32ac3b17;
}
//----------
// tail
u8 const * tail = cast(u8 const *)(data + nblocks*16);
u32 k1 = 0;
u32 k2 = 0;
u32 k3 = 0;
u32 k4 = 0;
switch(len & 15) {
case 15: k4 ^= tail[14] << 16;
case 14: k4 ^= tail[13] << 8;
case 13: k4 ^= tail[12] << 0;
k4 *= c4; k4 = ROTL32(k4,18); k4 *= c1; h4 ^= k4;
case 12: k3 ^= tail[11] << 24;
case 11: k3 ^= tail[10] << 16;
case 10: k3 ^= tail[ 9] << 8;
case 9: k3 ^= tail[ 8] << 0;
k3 *= c3; k3 = ROTL32(k3,17); k3 *= c4; h3 ^= k3;
case 8: k2 ^= tail[ 7] << 24;
case 7: k2 ^= tail[ 6] << 16;
case 6: k2 ^= tail[ 5] << 8;
case 5: k2 ^= tail[ 4] << 0;
k2 *= c2; k2 = ROTL32(k2,16); k2 *= c3; h2 ^= k2;
case 4: k1 ^= tail[ 3] << 24;
case 3: k1 ^= tail[ 2] << 16;
case 2: k1 ^= tail[ 1] << 8;
case 1: k1 ^= tail[ 0] << 0;
k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
};
//----------
// finalization
h1 ^= len; h2 ^= len; h3 ^= len; h4 ^= len;
h1 += h2; h1 += h3; h1 += h4;
h2 += h1; h3 += h1; h4 += h1;
h1 = fmix32(h1);
h2 = fmix32(h2);
h3 = fmix32(h3);
h4 = fmix32(h4);
h1 += h2; h1 += h3; h1 += h4;
h2 += h1; h3 += h1; h4 += h1;
((u32 *)out)[0] = h1;
((u32 *)out)[1] = h2;
((u32 *)out)[2] = h3;
((u32 *)out)[3] = h4;
}
// gb_inline u128 MurmurHash3_128(void const *key, isize len, u32 seed) {
// u128 res;
// #if defined(GB_ARCH_64_BIT)
// MurmurHash3_x64_128(key, len, seed, &res);
// #else
// MurmurHash3_x86_128(key, len, seed, &res);
// #endif
// return res;
// }
gb_internal gb_inline u32 murmur_32_scramble(u32 k) {
k *= 0xcc9e2d51;
k = (k << 15) | (k >> 17);
k *= 0x1b873593;
return k;
}
u32 murmur3_32(u8 const *key, isize len, u32 seed) {
u32 h = seed;
u32 k;
for (size_t i = len >> 2; i; i--) {
memcpy(&k, key, sizeof(u32));
key += sizeof(u32);
h ^= murmur_32_scramble(k);
h = (h << 13) | (h >> 19);
h = h * 5 + 0xe6546b64;
}
k = 0;
for (size_t i = len & 3; i; i--) {
k <<= 8;
k |= key[i - 1];
}
h ^= murmur_32_scramble(k);
h ^= len;
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
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