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Add xxhash header.

This commit is contained in:
BearOso 2023-02-21 16:25:40 -06:00
parent 8907541f28
commit e9ca336028
1 changed files with 99 additions and 0 deletions
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external/xxh64/xxh64.hpp vendored Normal file
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/*
* Copyright (c) 2015 Daniel Kirchner
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef XXH64_HPP
#define XXH64_HPP
#include <cstdint>
struct xxh64 {
static constexpr uint64_t hash (const char *p, uint64_t len, uint64_t seed) {
return finalize ((len >= 32 ? h32bytes (p, len, seed) : seed + PRIME5) + len, p + (len & ~0x1F), len & 0x1F);
}
private:
static constexpr uint64_t PRIME1 = 11400714785074694791ULL;
static constexpr uint64_t PRIME2 = 14029467366897019727ULL;
static constexpr uint64_t PRIME3 = 1609587929392839161ULL;
static constexpr uint64_t PRIME4 = 9650029242287828579ULL;
static constexpr uint64_t PRIME5 = 2870177450012600261ULL;
static constexpr uint64_t rotl (uint64_t x, int r) {
return ((x << r) | (x >> (64 - r)));
}
static constexpr uint64_t mix1 (const uint64_t h, const uint64_t prime, int rshift) {
return (h ^ (h >> rshift)) * prime;
}
static constexpr uint64_t mix2 (const uint64_t p, const uint64_t v = 0) {
return rotl (v + p * PRIME2, 31) * PRIME1;
}
static constexpr uint64_t mix3 (const uint64_t h, const uint64_t v) {
return (h ^ mix2 (v)) * PRIME1 + PRIME4;
}
#ifdef XXH64_BIG_ENDIAN
static constexpr uint32_t endian32 (const char *v) {
return uint32_t(uint8_t(v[3]))|(uint32_t(uint8_t(v[2]))<<8)
|(uint32_t(uint8_t(v[1]))<<16)|(uint32_t(uint8_t(v[0]))<<24);
}
static constexpr uint64_t endian64 (const char *v)
{
return uint64_t(uint8_t(v[7]))|(uint64_t(uint8_t(v[6]))<<8)
|(uint64_t(uint8_t(v[5]))<<16)|(uint64_t(uint8_t(v[4]))<<24)
|(uint64_t(uint8_t(v[3]))<<32)|(uint64_t(uint8_t(v[2]))<<40)
|(uint64_t(uint8_t(v[1]))<<48)|(uint64_t(uint8_t(v[0]))<<56);
}
#else
static constexpr uint32_t endian32 (const char *v) {
return uint32_t(uint8_t(v[0]))|(uint32_t(uint8_t(v[1]))<<8)
|(uint32_t(uint8_t(v[2]))<<16)|(uint32_t(uint8_t(v[3]))<<24);
}
static constexpr uint64_t endian64 (const char *v) {
return uint64_t(uint8_t(v[0]))|(uint64_t(uint8_t(v[1]))<<8)
|(uint64_t(uint8_t(v[2]))<<16)|(uint64_t(uint8_t(v[3]))<<24)
|(uint64_t(uint8_t(v[4]))<<32)|(uint64_t(uint8_t(v[5]))<<40)
|(uint64_t(uint8_t(v[6]))<<48)|(uint64_t(uint8_t(v[7]))<<56);
}
#endif
static constexpr uint64_t fetch64 (const char *p, const uint64_t v = 0) {
return mix2 (endian64 (p), v);
}
static constexpr uint64_t fetch32 (const char *p) {
return uint64_t (endian32 (p)) * PRIME1;
}
static constexpr uint64_t fetch8 (const char *p) {
return uint8_t (*p) * PRIME5;
}
static constexpr uint64_t finalize (const uint64_t h, const char *p, uint64_t len) {
return (len >= 8) ? (finalize (rotl (h ^ fetch64 (p), 27) * PRIME1 + PRIME4, p + 8, len - 8)) :
((len >= 4) ? (finalize (rotl (h ^ fetch32 (p), 23) * PRIME2 + PRIME3, p + 4, len - 4)) :
((len > 0) ? (finalize (rotl (h ^ fetch8 (p), 11) * PRIME1, p + 1, len - 1)) :
(mix1 (mix1 (mix1 (h, PRIME2, 33), PRIME3, 29), 1, 32))));
}
static constexpr uint64_t h32bytes (const char *p, uint64_t len, const uint64_t v1,const uint64_t v2, const uint64_t v3, const uint64_t v4) {
return (len >= 32) ? h32bytes (p + 32, len - 32, fetch64 (p, v1), fetch64 (p + 8, v2), fetch64 (p + 16, v3), fetch64 (p + 24, v4)) :
mix3 (mix3 (mix3 (mix3 (rotl (v1, 1) + rotl (v2, 7) + rotl (v3, 12) + rotl (v4, 18), v1), v2), v3), v4);
}
static constexpr uint64_t h32bytes (const char *p, uint64_t len, const uint64_t seed) {
return h32bytes (p, len, seed + PRIME1 + PRIME2, seed + PRIME2, seed, seed - PRIME1);
}
};
#endif /* !defined XXH64_HPP */