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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#include "misc/MurmurHash.h"
using namespace antlr4::misc;
// A variation of the MurmurHash3 implementation (https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp)
// Here we unrolled the loop used there into individual calls to update(), as we usually hash object fields
// instead of entire buffers.
// Platform-specific functions and macros
// Microsoft Visual Studio
#if defined(_MSC_VER)
#define FORCE_INLINE __forceinline
#include <stdlib.h>
#define ROTL32(x,y) _rotl(x,y)
#define ROTL64(x,y) _rotl64(x,y)
#define BIG_CONSTANT(x) (x)
#else // defined(_MSC_VER)
// Other compilers
#define FORCE_INLINE inline __attribute__((always_inline))
inline uint32_t rotl32 (uint32_t x, int8_t r)
{
return (x << r) | (x >> (32 - r));
}
inline uint64_t rotl64 (uint64_t x, int8_t r)
{
return (x << r) | (x >> (64 - r));
}
#define ROTL32(x,y) rotl32(x,y)
#define ROTL64(x,y) rotl64(x,y)
#define BIG_CONSTANT(x) (x##LLU)
#endif // !defined(_MSC_VER)
size_t MurmurHash::initialize() {
return initialize(DEFAULT_SEED);
}
size_t MurmurHash::initialize(size_t seed) {
return seed;
}
#if defined(_WIN32) || defined(_WIN64)
#if _WIN64
#define ENVIRONMENT64
#else
#define ENVIRONMENT32
#endif
#endif
#if defined(__GNUC__)
#if defined(__x86_64__) || defined(__ppc64__)
#define ENVIRONMENT64
#else
#define ENVIRONMENT32
#endif
#endif
#if defined(ENVIRONMENT32)
size_t MurmurHash::update(size_t hash, size_t value) {
static const size_t c1 = 0xCC9E2D51;
static const size_t c2 = 0x1B873593;
size_t k1 = value;
k1 *= c1;
k1 = ROTL32(k1, 15);
k1 *= c2;
hash ^= k1;
hash = ROTL32(hash, 13);
hash = hash * 5 + 0xE6546B64;
return hash;
}
size_t MurmurHash::finish(size_t hash, size_t entryCount) {
hash ^= entryCount * 4;
hash ^= hash >> 16;
hash *= 0x85EBCA6B;
hash ^= hash >> 13;
hash *= 0xC2B2AE35;
hash ^= hash >> 16;
return hash;
}
#else
size_t MurmurHash::update(size_t hash, size_t value) {
static const size_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
static const size_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
size_t k1 = value;
k1 *= c1;
k1 = ROTL64(k1, 31);
k1 *= c2;
hash ^= k1;
hash = ROTL64(hash, 27);
hash = hash * 5 + 0x52dce729;
return hash;
}
size_t MurmurHash::finish(size_t hash, size_t entryCount) {
hash ^= entryCount * 8;
hash ^= hash >> 33;
hash *= 0xff51afd7ed558ccd;
hash ^= hash >> 33;
hash *= 0xc4ceb9fe1a85ec53;
hash ^= hash >> 33;
return hash;
}
#endif
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