| // Copyright (c) 2014 Google, Inc. |
| // |
| // 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. |
| // |
| // FarmHash, by Geoff Pike |
| |
| // |
| // http://code.google.com/p/farmhash/ |
| // |
| // This file provides a few functions for hashing strings and other |
| // data. All of them are high-quality functions in the sense that |
| // they do well on standard tests such as Austin Appleby's SMHasher. |
| // They're also fast. FarmHash is the successor to CityHash. |
| // |
| // Functions in the FarmHash family are not suitable for cryptography. |
| // |
| // WARNING: This code has been only lightly tested on big-endian platforms! |
| // It is known to work well on little-endian platforms that have a small penalty |
| // for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs. |
| // It should work on all 32-bit and 64-bit platforms that allow unaligned reads; |
| // bug reports are welcome. |
| // |
| // By the way, for some hash functions, given strings a and b, the hash |
| // of a+b is easily derived from the hashes of a and b. This property |
| // doesn't hold for any hash functions in this file. |
| |
| #ifndef FARM_HASH_H_ |
| #define FARM_HASH_H_ |
| |
| #include <assert.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| #include <string.h> // for memcpy and memset |
| #include <utility> |
| |
| #ifndef NAMESPACE_FOR_HASH_FUNCTIONS |
| #define NAMESPACE_FOR_HASH_FUNCTIONS util |
| #endif |
| |
| namespace NAMESPACE_FOR_HASH_FUNCTIONS { |
| |
| #if defined(FARMHASH_UINT128_T_DEFINED) |
| inline uint64_t Uint128Low64(const uint128_t x) { |
| return static_cast<uint64_t>(x); |
| } |
| inline uint64_t Uint128High64(const uint128_t x) { |
| return static_cast<uint64_t>(x >> 64); |
| } |
| inline uint128_t Uint128(uint64_t lo, uint64_t hi) { |
| return lo + (((uint128_t)hi) << 64); |
| } |
| #else |
| typedef std::pair<uint64_t, uint64_t> uint128_t; |
| inline uint64_t Uint128Low64(const uint128_t x) { return x.first; } |
| inline uint64_t Uint128High64(const uint128_t x) { return x.second; } |
| inline uint128_t Uint128(uint64_t lo, uint64_t hi) { return uint128_t(lo, hi); } |
| #endif |
| |
| |
| // BASIC STRING HASHING |
| |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| size_t Hash(const char* s, size_t len); |
| |
| // Hash function for a byte array. Most useful in 32-bit binaries. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint32_t Hash32(const char* s, size_t len); |
| |
| // Hash function for a byte array. For convenience, a 32-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint32_t Hash32WithSeed(const char* s, size_t len, uint32_t seed); |
| |
| // Hash 128 input bits down to 64 bits of output. |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint64_t Hash64(const char* s, size_t len); |
| |
| // Hash function for a byte array. For convenience, a 64-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint64_t Hash64WithSeed(const char* s, size_t len, uint64_t seed); |
| |
| // Hash function for a byte array. For convenience, two seeds are also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint64_t Hash64WithSeeds(const char* s, size_t len, |
| uint64_t seed0, uint64_t seed1); |
| |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint128_t Hash128(const char* s, size_t len); |
| |
| // Hash function for a byte array. For convenience, a 128-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| uint128_t Hash128WithSeed(const char* s, size_t len, uint128_t seed); |
| |
| // BASIC NON-STRING HASHING |
| |
| // This is intended to be a reasonably good hash function. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| inline uint64_t Hash128to64(uint128_t x) { |
| // Murmur-inspired hashing. |
| const uint64_t kMul = 0x9ddfea08eb382d69ULL; |
| uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul; |
| a ^= (a >> 47); |
| uint64_t b = (Uint128High64(x) ^ a) * kMul; |
| b ^= (b >> 47); |
| b *= kMul; |
| return b; |
| } |
| |
| // FINGERPRINTING (i.e., good, portable, forever-fixed hash functions) |
| |
| // Fingerprint function for a byte array. Most useful in 32-bit binaries. |
| uint32_t Fingerprint32(const char* s, size_t len); |
| |
| // Fingerprint function for a byte array. |
| uint64_t Fingerprint64(const char* s, size_t len); |
| |
| // Fingerprint function for a byte array. |
| uint128_t Fingerprint128(const char* s, size_t len); |
| |
| // This is intended to be a good fingerprinting primitive. |
| // See below for more overloads. |
| inline uint64_t Fingerprint(uint128_t x) { |
| // Murmur-inspired hashing. |
| const uint64_t kMul = 0x9ddfea08eb382d69ULL; |
| uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul; |
| a ^= (a >> 47); |
| uint64_t b = (Uint128High64(x) ^ a) * kMul; |
| b ^= (b >> 44); |
| b *= kMul; |
| b ^= (b >> 41); |
| b *= kMul; |
| return b; |
| } |
| |
| // This is intended to be a good fingerprinting primitive. |
| inline uint64_t Fingerprint(uint64_t x) { |
| // Murmur-inspired hashing. |
| const uint64_t kMul = 0x9ddfea08eb382d69ULL; |
| uint64_t b = x * kMul; |
| b ^= (b >> 44); |
| b *= kMul; |
| b ^= (b >> 41); |
| b *= kMul; |
| return b; |
| } |
| |
| #ifndef FARMHASH_NO_CXX_STRING |
| |
| // Convenience functions to hash or fingerprint C++ strings. |
| // These require that Str::data() return a pointer to the first char |
| // (as a const char*) and that Str::length() return the string's length; |
| // they work with std::string, for example. |
| |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline size_t Hash(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Hash(s.data(), s.length()); |
| } |
| |
| // Hash function for a byte array. Most useful in 32-bit binaries. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint32_t Hash32(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Hash32(s.data(), s.length()); |
| } |
| |
| // Hash function for a byte array. For convenience, a 32-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint32_t Hash32WithSeed(const Str& s, uint32_t seed) { |
| assert(sizeof(s[0]) == 1); |
| return Hash32WithSeed(s.data(), s.length(), seed); |
| } |
| |
| // Hash 128 input bits down to 64 bits of output. |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint64_t Hash64(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Hash64(s.data(), s.length()); |
| } |
| |
| // Hash function for a byte array. For convenience, a 64-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint64_t Hash64WithSeed(const Str& s, uint64_t seed) { |
| assert(sizeof(s[0]) == 1); |
| return Hash64WithSeed(s.data(), s.length(), seed); |
| } |
| |
| // Hash function for a byte array. For convenience, two seeds are also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint64_t Hash64WithSeeds(const Str& s, uint64_t seed0, uint64_t seed1) { |
| assert(sizeof(s[0]) == 1); |
| return Hash64WithSeeds(s.data(), s.length(), seed0, seed1); |
| } |
| |
| // Hash function for a byte array. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint128_t Hash128(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Hash128(s.data(), s.length()); |
| } |
| |
| // Hash function for a byte array. For convenience, a 128-bit seed is also |
| // hashed into the result. |
| // May change from time to time, may differ on different platforms, may differ |
| // depending on NDEBUG. |
| template <typename Str> |
| inline uint128_t Hash128WithSeed(const Str& s, uint128_t seed) { |
| assert(sizeof(s[0]) == 1); |
| return Hash128(s.data(), s.length(), seed); |
| } |
| |
| // FINGERPRINTING (i.e., good, portable, forever-fixed hash functions) |
| |
| // Fingerprint function for a byte array. Most useful in 32-bit binaries. |
| template <typename Str> |
| inline uint32_t Fingerprint32(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Fingerprint32(s.data(), s.length()); |
| } |
| |
| // Fingerprint 128 input bits down to 64 bits of output. |
| // Fingerprint function for a byte array. |
| template <typename Str> |
| inline uint64_t Fingerprint64(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Fingerprint64(s.data(), s.length()); |
| } |
| |
| // Fingerprint function for a byte array. |
| template <typename Str> |
| inline uint128_t Fingerprint128(const Str& s) { |
| assert(sizeof(s[0]) == 1); |
| return Fingerprint128(s.data(), s.length()); |
| } |
| |
| #endif |
| |
| } // namespace NAMESPACE_FOR_HASH_FUNCTIONS |
| |
| #endif // FARM_HASH_H_ |