329 lines
11 KiB
C++
329 lines
11 KiB
C++
// Copyright (c) 2014 Google, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// FarmHash, by Geoff Pike
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//
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// http://code.google.com/p/farmhash/
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//
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// This file provides a few functions for hashing strings and other
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// data. All of them are high-quality functions in the sense that
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// they do well on standard tests such as Austin Appleby's SMHasher.
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// They're also fast. FarmHash is the successor to CityHash.
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//
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// Functions in the FarmHash family are not suitable for cryptography.
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//
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// WARNING: This code has been only lightly tested on big-endian platforms!
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// It is known to work well on little-endian platforms that have a small penalty
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// for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs.
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// It should work on all 32-bit and 64-bit platforms that allow unaligned reads;
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// bug reports are welcome.
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//
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// By the way, for some hash functions, given strings a and b, the hash
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// of a+b is easily derived from the hashes of a and b. This property
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// doesn't hold for any hash functions in this file.
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#ifndef FARM_HASH_H_
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#define FARM_HASH_H_
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#include <assert.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h> // for memcpy and memset
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#include <utility>
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#ifndef NAMESPACE_FOR_HASH_FUNCTIONS
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#define NAMESPACE_FOR_HASH_FUNCTIONS util
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#endif
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namespace NAMESPACE_FOR_HASH_FUNCTIONS {
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#if defined(FARMHASH_UINT128_T_DEFINED)
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#if defined(__clang__)
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#if !defined(uint128_t)
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#define uint128_t __uint128_t
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#endif
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#endif
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inline uint64_t Uint128Low64(const uint128_t x) {
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return static_cast<uint64_t>(x);
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}
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inline uint64_t Uint128High64(const uint128_t x) {
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return static_cast<uint64_t>(x >> 64);
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}
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inline uint128_t Uint128(uint64_t lo, uint64_t hi) {
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return lo + (((uint128_t)hi) << 64);
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}
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#else
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typedef std::pair<uint64_t, uint64_t> uint128_t;
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inline uint64_t Uint128Low64(const uint128_t x) { return x.first; }
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inline uint64_t Uint128High64(const uint128_t x) { return x.second; }
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inline uint128_t Uint128(uint64_t lo, uint64_t hi) { return uint128_t(lo, hi); }
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#endif
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// BASIC STRING HASHING
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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size_t Hash(const char* s, size_t len);
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// Hash function for a byte array. Most useful in 32-bit binaries.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint32_t Hash32(const char* s, size_t len);
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// Hash function for a byte array. For convenience, a 32-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint32_t Hash32WithSeed(const char* s, size_t len, uint32_t seed);
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint64_t Hash64(const char* s, size_t len);
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// Hash function for a byte array. For convenience, a 64-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint64_t Hash64WithSeed(const char* s, size_t len, uint64_t seed);
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// Hash function for a byte array. For convenience, two seeds are also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint64_t Hash64WithSeeds(const char* s, size_t len,
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uint64_t seed0, uint64_t seed1);
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint128_t Hash128(const char* s, size_t len);
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// Hash function for a byte array. For convenience, a 128-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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uint128_t Hash128WithSeed(const char* s, size_t len, uint128_t seed);
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// BASIC NON-STRING HASHING
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// Hash 128 input bits down to 64 bits of output.
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// This is intended to be a reasonably good hash function.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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inline uint64_t Hash128to64(uint128_t x) {
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// Murmur-inspired hashing.
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const uint64_t kMul = 0x9ddfea08eb382d69ULL;
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uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
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a ^= (a >> 47);
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uint64_t b = (Uint128High64(x) ^ a) * kMul;
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b ^= (b >> 47);
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b *= kMul;
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return b;
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}
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// FINGERPRINTING (i.e., good, portable, forever-fixed hash functions)
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// Fingerprint function for a byte array. Most useful in 32-bit binaries.
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uint32_t Fingerprint32(const char* s, size_t len);
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// Fingerprint function for a byte array.
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uint64_t Fingerprint64(const char* s, size_t len);
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// Fingerprint function for a byte array.
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uint128_t Fingerprint128(const char* s, size_t len);
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// This is intended to be a good fingerprinting primitive.
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// See below for more overloads.
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inline uint64_t Fingerprint(uint128_t x) {
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// Murmur-inspired hashing.
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const uint64_t kMul = 0x9ddfea08eb382d69ULL;
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uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
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a ^= (a >> 47);
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uint64_t b = (Uint128High64(x) ^ a) * kMul;
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b ^= (b >> 44);
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b *= kMul;
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b ^= (b >> 41);
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b *= kMul;
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return b;
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}
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// This is intended to be a good fingerprinting primitive.
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inline uint64_t Fingerprint(uint64_t x) {
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// Murmur-inspired hashing.
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const uint64_t kMul = 0x9ddfea08eb382d69ULL;
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uint64_t b = x * kMul;
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b ^= (b >> 44);
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b *= kMul;
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b ^= (b >> 41);
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b *= kMul;
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return b;
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}
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#ifndef FARMHASH_NO_CXX_STRING
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// Convenience functions to hash or fingerprint C++ strings.
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// These require that Str::data() return a pointer to the first char
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// (as a const char*) and that Str::length() return the string's length;
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// they work with std::string, for example.
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline size_t Hash(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Hash(s.data(), s.length());
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}
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// Hash function for a byte array. Most useful in 32-bit binaries.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint32_t Hash32(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Hash32(s.data(), s.length());
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}
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// Hash function for a byte array. For convenience, a 32-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint32_t Hash32WithSeed(const Str& s, uint32_t seed) {
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assert(sizeof(s[0]) == 1);
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return Hash32WithSeed(s.data(), s.length(), seed);
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}
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// Hash 128 input bits down to 64 bits of output.
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint64_t Hash64(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Hash64(s.data(), s.length());
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}
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// Hash function for a byte array. For convenience, a 64-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint64_t Hash64WithSeed(const Str& s, uint64_t seed) {
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assert(sizeof(s[0]) == 1);
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return Hash64WithSeed(s.data(), s.length(), seed);
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}
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// Hash function for a byte array. For convenience, two seeds are also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint64_t Hash64WithSeeds(const Str& s, uint64_t seed0, uint64_t seed1) {
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assert(sizeof(s[0]) == 1);
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return Hash64WithSeeds(s.data(), s.length(), seed0, seed1);
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}
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// Hash function for a byte array.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint128_t Hash128(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Hash128(s.data(), s.length());
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}
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// Hash function for a byte array. For convenience, a 128-bit seed is also
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// hashed into the result.
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// May change from time to time, may differ on different platforms, may differ
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// depending on NDEBUG.
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template <typename Str>
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inline uint128_t Hash128WithSeed(const Str& s, uint128_t seed) {
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assert(sizeof(s[0]) == 1);
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return Hash128(s.data(), s.length(), seed);
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}
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// FINGERPRINTING (i.e., good, portable, forever-fixed hash functions)
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// Fingerprint function for a byte array. Most useful in 32-bit binaries.
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template <typename Str>
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inline uint32_t Fingerprint32(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Fingerprint32(s.data(), s.length());
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}
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// Fingerprint 128 input bits down to 64 bits of output.
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// Fingerprint function for a byte array.
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template <typename Str>
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inline uint64_t Fingerprint64(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Fingerprint64(s.data(), s.length());
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}
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// Fingerprint function for a byte array.
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template <typename Str>
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inline uint128_t Fingerprint128(const Str& s) {
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assert(sizeof(s[0]) == 1);
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return Fingerprint128(s.data(), s.length());
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}
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#endif
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} // namespace NAMESPACE_FOR_HASH_FUNCTIONS
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/* gently define FARMHASH_BIG_ENDIAN when detected big-endian machine */
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#if defined(__BIG_ENDIAN__)
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#if !defined(FARMHASH_BIG_ENDIAN)
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#define FARMHASH_BIG_ENDIAN
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#endif
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#elif defined(__LITTLE_ENDIAN__)
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// nothing for little-endian
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#elif defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && (__BYTE_ORDER == __ORDER_LITTLE_ENDIAN__)
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// nothing for little-endian
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#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && (__BYTE_ORDER == __ORDER_BIG_ENDIAN__)
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#if !defined(FARMHASH_BIG_ENDIAN)
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#define FARMHASH_BIG_ENDIAN
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#endif
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#elif defined(__linux__) || defined(__CYGWIN__) || defined( __GNUC__ ) && !defined(_WIN32) || defined( __GNU_LIBRARY__ )
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#include <endian.h> // libc6-dev, GLIBC
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#if BYTE_ORDER == BIG_ENDIAN
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#if !defined(FARMHASH_BIG_ENDIAN)
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#define FARMHASH_BIG_ENDIAN
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#endif
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#endif
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#elif defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__) || defined(__s390x__)
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#include <sys/endian.h>
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#if BYTE_ORDER == BIG_ENDIAN
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#if !defined(FARMHASH_BIG_ENDIAN)
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#define FARMHASH_BIG_ENDIAN
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#endif
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#endif
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#elif defined(_WIN32)
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// Windows is (currently) little-endian
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#else
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#error "Unable to determine endianness!"
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#endif /* __BIG_ENDIAN__ */
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#endif // FARM_HASH_H_
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