76 lines
3 KiB
C++
76 lines
3 KiB
C++
// Copyright (c) 2011 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.
|
|
//
|
|
// CityHash, by Geoff Pike and Jyrki Alakuijala
|
|
//
|
|
// This file provides a few functions for hashing strings. On x86-64
|
|
// hardware in 2011, CityHash64() is faster than other high-quality
|
|
// hash functions, such as Murmur. This is largely due to higher
|
|
// instruction-level parallelism. CityHash64() and CityHash128() also perform
|
|
// well on hash-quality tests.
|
|
//
|
|
// CityHash128() is optimized for relatively long strings and returns
|
|
// a 128-bit hash. For strings more than about 2000 bytes it can be
|
|
// faster than CityHash64().
|
|
//
|
|
// Functions in the CityHash family are not suitable for cryptography.
|
|
//
|
|
// WARNING: This code has not been 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.
|
|
//
|
|
// 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.
|
|
#pragma once
|
|
|
|
#include <stdlib.h> // for size_t.
|
|
#include <stdint.h>
|
|
#include <utility>
|
|
|
|
namespace fc {
|
|
|
|
template<typename T, size_t N>
|
|
class array;
|
|
class uint128;
|
|
|
|
// Hash function for a byte array.
|
|
uint64_t city_hash64(const char *buf, size_t len);
|
|
|
|
uint32_t city_hash32(const char *buf, size_t len);
|
|
|
|
#if SIZE_MAX > UINT32_MAX
|
|
inline size_t city_hash_size_t(const char *buf, size_t len) { return city_hash64(buf, len); }
|
|
#else
|
|
inline size_t city_hash_size_t(const char *buf, size_t len) { return city_hash32(buf, len); }
|
|
#endif
|
|
|
|
// Hash function for a byte array.
|
|
uint128 city_hash128(const char *s, size_t len);
|
|
|
|
// Hash function for a byte array.
|
|
uint64_t city_hash_crc_64(const char *buf, size_t len);
|
|
|
|
// Hash function for a byte array.
|
|
uint128 city_hash_crc_128(const char *s, size_t len);
|
|
array<uint64_t,4> city_hash_crc_256(const char *s, size_t len);
|
|
|
|
|
|
} // namespace fc
|