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420 lines
10 KiB
C++
420 lines
10 KiB
C++
#ifndef HASHFUNCS_H
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#define HASHFUNCS_H
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/*************************************************************************/
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/* hashfuncs.h */
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/* From https://github.com/Relintai/pandemonium_engine (MIT) */
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/*************************************************************************/
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//--STRIP
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#include "core/math_defs.h"
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#include "core/math_funcs.h"
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#include "core/string_name.h"
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#include "core/ustring.h"
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#include "core/typedefs.h"
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//--STRIP
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/**
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* Hashing functions
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*/
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/**
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* DJB2 Hash function
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* @param C String
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* @return 32-bits hashcode
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*/
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static inline uint32_t hash_djb2(const char *p_cstr) {
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const unsigned char *chr = (const unsigned char *)p_cstr;
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uint32_t hash = 5381;
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uint32_t c;
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while ((c = *chr++)) {
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hash = ((hash << 5) + hash) ^ c; /* hash * 33 ^ c */
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}
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return hash;
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}
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static inline uint32_t hash_djb2_buffer(const uint8_t *p_buff, int p_len, uint32_t p_prev = 5381) {
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uint32_t hash = p_prev;
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for (int i = 0; i < p_len; i++) {
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hash = ((hash << 5) + hash) ^ p_buff[i]; /* hash * 33 ^ c */
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}
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return hash;
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}
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static inline uint32_t hash_djb2_one_32(uint32_t p_in, uint32_t p_prev = 5381) {
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return ((p_prev << 5) + p_prev) ^ p_in;
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}
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/**
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* Thomas Wang's 64-bit to 32-bit Hash function:
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* https://web.archive.org/web/20071223173210/https:/www.concentric.net/~Ttwang/tech/inthash.htm
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*
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* @param p_int - 64-bit unsigned integer key to be hashed
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* @return unsigned 32-bit value representing hashcode
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*/
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static inline uint32_t hash_one_uint64(const uint64_t p_int) {
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uint64_t v = p_int;
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v = (~v) + (v << 18); // v = (v << 18) - v - 1;
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v = v ^ (v >> 31);
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v = v * 21; // v = (v + (v << 2)) + (v << 4);
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v = v ^ (v >> 11);
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v = v + (v << 6);
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v = v ^ (v >> 22);
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return (uint32_t)v;
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}
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#define HASH_MURMUR3_SEED 0x7F07C65
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// Murmurhash3 32-bit version.
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// All MurmurHash versions are public domain software, and the author disclaims all copyright to their code.
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static _FORCE_INLINE_ uint32_t hash_murmur3_one_32(uint32_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED) {
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p_in *= 0xcc9e2d51;
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p_in = (p_in << 15) | (p_in >> 17);
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p_in *= 0x1b873593;
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p_seed ^= p_in;
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p_seed = (p_seed << 13) | (p_seed >> 19);
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p_seed = p_seed * 5 + 0xe6546b64;
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return p_seed;
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}
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static _FORCE_INLINE_ uint32_t hash_murmur3_one_float(float p_in, uint32_t p_seed = HASH_MURMUR3_SEED) {
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union {
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float f;
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uint32_t i;
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} u;
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// Normalize +/- 0.0 and NaN values so they hash the same.
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if (p_in == 0.0f) {
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u.f = 0.0;
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} else if (Math::is_nan(p_in)) {
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u.f = NAN;
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} else {
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u.f = p_in;
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}
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return hash_murmur3_one_32(u.i, p_seed);
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}
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static _FORCE_INLINE_ uint32_t hash_murmur3_one_64(uint64_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED) {
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p_seed = hash_murmur3_one_32(p_in & 0xFFFFFFFF, p_seed);
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return hash_murmur3_one_32(p_in >> 32, p_seed);
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}
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static _FORCE_INLINE_ uint32_t hash_murmur3_one_double(double p_in, uint32_t p_seed = HASH_MURMUR3_SEED) {
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union {
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double d;
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uint64_t i;
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} u;
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// Normalize +/- 0.0 and NaN values so they hash the same.
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if (p_in == 0.0f) {
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u.d = 0.0;
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} else if (Math::is_nan(p_in)) {
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u.d = NAN;
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} else {
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u.d = p_in;
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}
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return hash_murmur3_one_64(u.i, p_seed);
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}
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static _FORCE_INLINE_ uint32_t hash_murmur3_one_real(real_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED) {
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#ifdef REAL_T_IS_DOUBLE
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return hash_murmur3_one_double(p_in, p_seed);
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#else
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return hash_murmur3_one_float(p_in, p_seed);
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#endif
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}
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static _FORCE_INLINE_ uint32_t hash_rotl32(uint32_t x, int8_t r) {
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return (x << r) | (x >> (32 - r));
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}
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static _FORCE_INLINE_ uint32_t hash_fmix32(uint32_t h) {
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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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static _FORCE_INLINE_ uint32_t hash_murmur3_buffer(const void *key, int length, const uint32_t seed = HASH_MURMUR3_SEED) {
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// Although not required, this is a random prime number.
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const uint8_t *data = (const uint8_t *)key;
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const int nblocks = length / 4;
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uint32_t h1 = seed;
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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const uint32_t *blocks = (const uint32_t *)(data + nblocks * 4);
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for (int i = -nblocks; i; i++) {
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uint32_t k1 = blocks[i];
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k1 *= c1;
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k1 = hash_rotl32(k1, 15);
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k1 *= c2;
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h1 ^= k1;
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h1 = hash_rotl32(h1, 13);
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h1 = h1 * 5 + 0xe6546b64;
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}
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const uint8_t *tail = (const uint8_t *)(data + nblocks * 4);
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uint32_t k1 = 0;
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switch (length & 3) {
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case 3:
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k1 ^= tail[2] << 16;
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FALLTHROUGH;
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case 2:
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k1 ^= tail[1] << 8;
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FALLTHROUGH;
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case 1:
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k1 ^= tail[0];
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k1 *= c1;
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k1 = hash_rotl32(k1, 15);
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k1 *= c2;
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h1 ^= k1;
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};
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// Finalize with additional bit mixing.
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h1 ^= length;
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return hash_fmix32(h1);
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}
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static inline uint32_t hash_djb2_one_float(double p_in, uint32_t p_prev = 5381) {
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union {
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double d;
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uint64_t i;
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} u;
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// Normalize +/- 0.0 and NaN values so they hash the same.
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if (p_in == 0.0f) {
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u.d = 0.0;
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} else if (Math::is_nan(p_in)) {
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u.d = Math_NAN;
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} else {
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u.d = p_in;
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}
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return ((p_prev << 5) + p_prev) + hash_one_uint64(u.i);
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}
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template <class T>
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static inline uint32_t make_uint32_t(T p_in) {
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union {
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T t;
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uint32_t _u32;
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} _u;
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_u._u32 = 0;
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_u.t = p_in;
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return _u._u32;
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}
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static _FORCE_INLINE_ uint64_t hash_djb2_one_float_64(double p_in, uint64_t p_prev = 5381) {
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union {
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double d;
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uint64_t i;
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} u;
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// Normalize +/- 0.0 and NaN values so they hash the same.
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if (p_in == 0.0f) {
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u.d = 0.0;
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} else if (Math::is_nan(p_in)) {
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u.d = NAN;
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} else {
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u.d = p_in;
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}
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return ((p_prev << 5) + p_prev) + u.i;
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}
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static _FORCE_INLINE_ uint64_t hash_djb2_one_64(uint64_t p_in, uint64_t p_prev = 5381) {
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return ((p_prev << 5) + p_prev) ^ p_in;
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}
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template <class T>
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static _FORCE_INLINE_ uint64_t hash_make_uint64_t(T p_in) {
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union {
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T t;
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uint64_t _u64;
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} _u;
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_u._u64 = 0; // in case p_in is smaller
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_u.t = p_in;
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return _u._u64;
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}
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template <class T>
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static inline uint64_t make_uint64_t(T p_in) {
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union {
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T t;
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uint64_t _u64;
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} _u;
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_u._u64 = 0; // in case p_in is smaller
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_u.t = p_in;
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return _u._u64;
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}
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template <class T>
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class Ref;
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struct HashMapHasherDefault {
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// Generic hash function for any type.
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template <class T>
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static _FORCE_INLINE_ uint32_t hash(const T *p_pointer) { return hash_one_uint64((uint64_t)p_pointer); }
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template <class T>
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static _FORCE_INLINE_ uint32_t hash(const Ref<T> &p_ref) { return hash_one_uint64((uint64_t)p_ref.operator->()); }
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static _FORCE_INLINE_ uint32_t hash(const String &p_string) { return p_string.hash(); }
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static _FORCE_INLINE_ uint32_t hash(const char *p_cstr) { return hash_djb2(p_cstr); }
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static _FORCE_INLINE_ uint32_t hash(const wchar_t p_wchar) { return hash_fmix32(p_wchar); }
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static _FORCE_INLINE_ uint32_t hash(const char16_t p_uchar) { return hash_fmix32(p_uchar); }
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static _FORCE_INLINE_ uint32_t hash(const char32_t p_uchar) { return hash_fmix32(p_uchar); }
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static _FORCE_INLINE_ uint32_t hash(const StringName &p_string_name) { return p_string_name.hash(); }
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static _FORCE_INLINE_ uint32_t hash(const uint64_t p_int) { return hash_one_uint64(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const int64_t p_int) { return hash_one_uint64(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const float p_float) { return hash_murmur3_one_float(p_float); }
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static _FORCE_INLINE_ uint32_t hash(const double p_double) { return hash_murmur3_one_double(p_double); }
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static _FORCE_INLINE_ uint32_t hash(const uint32_t p_int) { return hash_fmix32(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const int32_t p_int) { return hash_fmix32(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const uint16_t p_int) { return hash_fmix32(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const int16_t p_int) { return hash_fmix32(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const uint8_t p_int) { return hash_fmix32(p_int); }
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static _FORCE_INLINE_ uint32_t hash(const int8_t p_int) { return hash_fmix32(p_int); }
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};
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template <typename T>
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struct HashMapComparatorDefault {
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static bool compare(const T &p_lhs, const T &p_rhs) {
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return p_lhs == p_rhs;
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}
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};
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template <>
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struct HashMapComparatorDefault<float> {
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static bool compare(const float &p_lhs, const float &p_rhs) {
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return (p_lhs == p_rhs) || (Math::is_nan(p_lhs) && Math::is_nan(p_rhs));
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}
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};
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template <>
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struct HashMapComparatorDefault<double> {
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static bool compare(const double &p_lhs, const double &p_rhs) {
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return (p_lhs == p_rhs) || (Math::is_nan(p_lhs) && Math::is_nan(p_rhs));
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}
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};
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constexpr uint32_t HASH_TABLE_SIZE_MAX = 29;
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const uint32_t hash_table_size_primes[HASH_TABLE_SIZE_MAX] = {
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5,
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13,
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23,
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47,
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97,
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193,
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389,
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769,
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1543,
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3079,
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6151,
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12289,
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24593,
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49157,
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98317,
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196613,
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393241,
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786433,
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1572869,
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3145739,
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6291469,
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12582917,
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25165843,
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50331653,
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100663319,
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201326611,
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402653189,
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805306457,
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1610612741,
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};
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// Computed with elem_i = UINT64_C (0 x FFFFFFFF FFFFFFFF ) / d_i + 1, where d_i is the i-th element of the above array.
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const uint64_t hash_table_size_primes_inv[HASH_TABLE_SIZE_MAX] = {
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3689348814741910324,
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1418980313362273202,
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802032351030850071,
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392483916461905354,
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190172619316593316,
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95578984837873325,
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47420935922132524,
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23987963684927896,
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11955116055547344,
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5991147799191151,
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2998982941588287,
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1501077717772769,
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750081082979285,
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375261795343686,
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187625172388393,
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93822606204624,
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46909513691883,
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23456218233098,
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11728086747027,
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5864041509391,
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2932024948977,
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1466014921160,
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733007198436,
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366503839517,
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183251896093,
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91625960335,
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45812983922,
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22906489714,
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11453246088
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};
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/**
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* Fastmod computes ( n mod d ) given the precomputed c much faster than n % d.
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* The implementation of fastmod is based on the following paper by Daniel Lemire et al.
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* Faster Remainder by Direct Computation: Applications to Compilers and Software Libraries
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* https://arxiv.org/abs/1902.01961
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*/
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static _FORCE_INLINE_ uint32_t fastmod(const uint32_t n, const uint64_t c, const uint32_t d) {
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#if defined(_MSC_VER)
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// Returns the upper 64 bits of the product of two 64-bit unsigned integers.
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// This intrinsic function is required since MSVC does not support unsigned 128-bit integers.
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#if defined(_M_X64) || defined(_M_ARM64)
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return __umulh(c * n, d);
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#else
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// Fallback to the slower method for 32-bit platforms.
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return n % d;
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#endif // _M_X64 || _M_ARM64
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#else
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#ifdef __SIZEOF_INT128__
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// Prevent compiler warning, because we know what we are doing.
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uint64_t lowbits = c * n;
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__extension__ typedef unsigned __int128 uint128;
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return static_cast<uint64_t>(((uint128)lowbits * d) >> 64);
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#else
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// Fallback to the slower method if no 128-bit unsigned integer type is available.
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return n % d;
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#endif // __SIZEOF_INT128__
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#endif // _MSC_VER
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}
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#endif // HASHFUNCS_H
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