michael@0: // Copyright (c) 2011 Google, Inc.
michael@0: //
michael@0: // Permission is hereby granted, free of charge, to any person obtaining a copy
michael@0: // of this software and associated documentation files (the "Software"), to deal
michael@0: // in the Software without restriction, including without limitation the rights
michael@0: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
michael@0: // copies of the Software, and to permit persons to whom the Software is
michael@0: // furnished to do so, subject to the following conditions:
michael@0: //
michael@0: // The above copyright notice and this permission notice shall be included in
michael@0: // all copies or substantial portions of the Software.
michael@0: //
michael@0: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
michael@0: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
michael@0: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
michael@0: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
michael@0: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
michael@0: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
michael@0: // THE SOFTWARE.
michael@0: //
michael@0: // CityHash Version 1, by Geoff Pike and Jyrki Alakuijala
michael@0: //
michael@0: // This file provides a few functions for hashing strings. On x86-64
michael@0: // hardware in 2011, CityHash64() is faster than other high-quality
michael@0: // hash functions, such as Murmur.  This is largely due to higher
michael@0: // instruction-level parallelism.  CityHash64() and CityHash128() also perform
michael@0: // well on hash-quality tests.
michael@0: //
michael@0: // CityHash128() is optimized for relatively long strings and returns
michael@0: // a 128-bit hash.  For strings more than about 2000 bytes it can be
michael@0: // faster than CityHash64().
michael@0: //
michael@0: // Functions in the CityHash family are not suitable for cryptography.
michael@0: //
michael@0: // WARNING: This code has not been tested on big-endian platforms!
michael@0: // It is known to work well on little-endian platforms that have a small penalty
michael@0: // for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs.
michael@0: //
michael@0: // By the way, for some hash functions, given strings a and b, the hash
michael@0: // of a+b is easily derived from the hashes of a and b.  This property
michael@0: // doesn't hold for any hash functions in this file.
michael@0: 
michael@0: #ifndef CITY_HASH_H_
michael@0: #define CITY_HASH_H_
michael@0: 
michael@0: #include "../CityHash.h" // added by moz, specific to nsis project
michael@0: 
michael@0: #include <stdlib.h>  // for size_t.
michael@0: #include <utility>
michael@0: 
michael@0: typedef unsigned __int8 uint8;
michael@0: typedef unsigned __int32 uint32;
michael@0: typedef unsigned __int64 uint64;
michael@0: typedef std::pair<uint64, uint64> uint128;
michael@0: 
michael@0: inline uint64 Uint128Low64(const uint128& x) { return x.first; }
michael@0: inline uint64 Uint128High64(const uint128& x) { return x.second; }
michael@0: 
michael@0: // Hash function for a byte array.
michael@0: uint64 CityHash64(const char *buf, size_t len);
michael@0: 
michael@0: // Hash function for a byte array.  For convenience, a 64-bit seed is also
michael@0: // hashed into the result.
michael@0: uint64 CityHash64WithSeed(const char *buf, size_t len, uint64 seed);
michael@0: 
michael@0: // Hash function for a byte array.  For convenience, two seeds are also
michael@0: // hashed into the result.
michael@0: uint64 CityHash64WithSeeds(const char *buf, size_t len,
michael@0:                            uint64 seed0, uint64 seed1);
michael@0: 
michael@0: // Hash function for a byte array.
michael@0: uint128 CityHash128(const char *s, size_t len);
michael@0: 
michael@0: // Hash function for a byte array.  For convenience, a 128-bit seed is also
michael@0: // hashed into the result.
michael@0: uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed);
michael@0: 
michael@0: // Hash 128 input bits down to 64 bits of output.
michael@0: // This is intended to be a reasonably good hash function.
michael@0: inline uint64 Hash128to64(const uint128& x) {
michael@0:   // Murmur-inspired hashing.
michael@0:   const uint64 kMul = 0x9ddfea08eb382d69;
michael@0:   uint64 a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
michael@0:   a ^= (a >> 47);
michael@0:   uint64 b = (Uint128High64(x) ^ a) * kMul;
michael@0:   b ^= (b >> 47);
michael@0:   b *= kMul;
michael@0:   return b;
michael@0: }
michael@0: 
michael@0: #endif  // CITY_HASH_H_