118 lines
2.6 KiB
C++
118 lines
2.6 KiB
C++
/* SPDX-FileCopyrightText: 2018-2022 Blender Foundation
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0 */
|
|
|
|
/* This is taken from alShaders/Cryptomatte/MurmurHash3.h:
|
|
*
|
|
* MurmurHash3 was written by Austin Appleby, and is placed in the public
|
|
* domain. The author hereby disclaims copyright to this source code.
|
|
*/
|
|
|
|
#include <cstdlib>
|
|
#include <cstring>
|
|
|
|
#include "util/math.h"
|
|
#include "util/murmurhash.h"
|
|
|
|
#if defined(_MSC_VER)
|
|
# define ROTL32(x, y) _rotl(x, y)
|
|
# define ROTL64(x, y) _rotl64(x, y)
|
|
# define BIG_CONSTANT(x) (x)
|
|
#else
|
|
ccl_device_inline uint32_t rotl32(const uint32_t x, int8_t r)
|
|
{
|
|
return (x << r) | (x >> (32 - r));
|
|
}
|
|
# define ROTL32(x, y) rotl32(x, y)
|
|
# define BIG_CONSTANT(x) (x##LLU)
|
|
#endif
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
/* Block read - if your platform needs to do endian-swapping or can only
|
|
* handle aligned reads, do the conversion here. */
|
|
ccl_device_inline uint32_t mm_hash_getblock32(const uint32_t *p, const int i)
|
|
{
|
|
return p[i];
|
|
}
|
|
|
|
/* Finalization mix - force all bits of a hash block to avalanche */
|
|
ccl_device_inline uint32_t mm_hash_fmix32(uint32_t h)
|
|
{
|
|
h ^= h >> 16;
|
|
h *= 0x85ebca6b;
|
|
h ^= h >> 13;
|
|
h *= 0xc2b2ae35;
|
|
h ^= h >> 16;
|
|
return h;
|
|
}
|
|
|
|
uint32_t util_murmur_hash3(const void *key, const int len, const uint32_t seed)
|
|
{
|
|
const uint8_t *data = (const uint8_t *)key;
|
|
const int nblocks = len / 4;
|
|
|
|
uint32_t h1 = seed;
|
|
|
|
const uint32_t c1 = 0xcc9e2d51;
|
|
const uint32_t c2 = 0x1b873593;
|
|
|
|
const uint32_t *blocks = (const uint32_t *)(data + nblocks * 4);
|
|
|
|
for (int i = -nblocks; i; i++) {
|
|
uint32_t k1 = mm_hash_getblock32(blocks, i);
|
|
|
|
k1 *= c1;
|
|
k1 = ROTL32(k1, 15);
|
|
k1 *= c2;
|
|
|
|
h1 ^= k1;
|
|
h1 = ROTL32(h1, 13);
|
|
h1 = h1 * 5 + 0xe6546b64;
|
|
}
|
|
|
|
const uint8_t *tail = (const uint8_t *)(data + nblocks * 4);
|
|
|
|
uint32_t k1 = 0;
|
|
|
|
switch (len & 3) {
|
|
case 3:
|
|
k1 ^= tail[2] << 16;
|
|
ATTR_FALLTHROUGH;
|
|
case 2:
|
|
k1 ^= tail[1] << 8;
|
|
ATTR_FALLTHROUGH;
|
|
case 1:
|
|
k1 ^= tail[0];
|
|
k1 *= c1;
|
|
k1 = ROTL32(k1, 15);
|
|
k1 *= c2;
|
|
h1 ^= k1;
|
|
ATTR_FALLTHROUGH;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
h1 ^= len;
|
|
h1 = mm_hash_fmix32(h1);
|
|
return h1;
|
|
}
|
|
|
|
/* This is taken from the cryptomatte specification 1.0 */
|
|
float util_hash_to_float(const uint32_t hash)
|
|
{
|
|
const uint32_t mantissa = hash & ((1 << 23) - 1);
|
|
uint32_t exponent = (hash >> 23) & ((1 << 8) - 1);
|
|
exponent = max(exponent, (uint32_t)1);
|
|
exponent = min(exponent, (uint32_t)254);
|
|
exponent = exponent << 23;
|
|
uint32_t sign = (hash >> 31);
|
|
sign = sign << 31;
|
|
uint32_t float_bits = sign | exponent | mantissa;
|
|
float f;
|
|
memcpy(&f, &float_bits, sizeof(uint32_t));
|
|
return f;
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|