xxhash.h revision 262395
1/* 2 xxHash - Fast Hash algorithm 3 Header File 4 Copyright (C) 2012-2013, Yann Collet. 5 BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) 6 7 Redistribution and use in source and binary forms, with or without 8 modification, are permitted provided that the following conditions are 9 met: 10 11 * Redistributions of source code must retain the above copyright 12 notice, this list of conditions and the following disclaimer. 13 * Redistributions in binary form must reproduce the above 14 copyright notice, this list of conditions and the following disclaimer 15 in the documentation and/or other materials provided with the 16 distribution. 17 18 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 You can contact the author at : 31 - xxHash source repository : http://code.google.com/p/xxhash/ 32*/ 33 34/* Notice extracted from xxHash homepage : 35 36xxHash is an extremely fast Hash algorithm, running at RAM speed limits. 37It also successfully passes all tests from the SMHasher suite. 38 39Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2 Duo @3GHz) 40 41Name Speed Q.Score Author 42xxHash 5.4 GB/s 10 43CrapWow 3.2 GB/s 2 Andrew 44MumurHash 3a 2.7 GB/s 10 Austin Appleby 45SpookyHash 2.0 GB/s 10 Bob Jenkins 46SBox 1.4 GB/s 9 Bret Mulvey 47Lookup3 1.2 GB/s 9 Bob Jenkins 48SuperFastHash 1.2 GB/s 1 Paul Hsieh 49CityHash64 1.05 GB/s 10 Pike & Alakuijala 50FNV 0.55 GB/s 5 Fowler, Noll, Vo 51CRC32 0.43 GB/s 9 52MD5-32 0.33 GB/s 10 Ronald L. Rivest 53SHA1-32 0.28 GB/s 10 54 55Q.Score is a measure of quality of the hash function. 56It depends on successfully passing SMHasher test set. 5710 is a perfect score. 58*/ 59 60#pragma once 61 62#if defined (__cplusplus) 63extern "C" { 64#endif 65 66 67//**************************** 68// Type 69//**************************** 70typedef enum { XXH_OK=0, XXH_ERROR } XXH_errorcode; 71 72 73 74//**************************** 75// Simple Hash Functions 76//**************************** 77 78unsigned int XXH32 (const void* input, int len, unsigned int seed); 79 80/* 81XXH32() : 82 Calculate the 32-bits hash of sequence of length "len" stored at memory address "input". 83 The memory between input & input+len must be valid (allocated and read-accessible). 84 "seed" can be used to alter the result predictably. 85 This function successfully passes all SMHasher tests. 86 Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s 87 Note that "len" is type "int", which means it is limited to 2^31-1. 88 If your data is larger, use the advanced functions below. 89*/ 90 91 92 93//**************************** 94// Advanced Hash Functions 95//**************************** 96 97void* XXH32_init (unsigned int seed); 98XXH_errorcode XXH32_update (void* state, const void* input, int len); 99unsigned int XXH32_digest (void* state); 100 101/* 102These functions calculate the xxhash of an input provided in several small packets, 103as opposed to an input provided as a single block. 104 105It must be started with : 106void* XXH32_init() 107The function returns a pointer which holds the state of calculation. 108 109This pointer must be provided as "void* state" parameter for XXH32_update(). 110XXH32_update() can be called as many times as necessary. 111The user must provide a valid (allocated) input. 112The function returns an error code, with 0 meaning OK, and any other value meaning there is an error. 113Note that "len" is type "int", which means it is limited to 2^31-1. 114If your data is larger, it is recommended to chunk your data into blocks 115of size for example 2^30 (1GB) to avoid any "int" overflow issue. 116 117Finally, you can end the calculation anytime, by using XXH32_digest(). 118This function returns the final 32-bits hash. 119You must provide the same "void* state" parameter created by XXH32_init(). 120Memory will be freed by XXH32_digest(). 121*/ 122 123 124int XXH32_sizeofState(void); 125XXH_errorcode XXH32_resetState(void* state, unsigned int seed); 126 127#define XXH32_SIZEOFSTATE 48 128typedef struct { long long ll[(XXH32_SIZEOFSTATE+(sizeof(long long)-1))/sizeof(long long)]; } XXH32_stateSpace_t; 129/* 130These functions allow user application to make its own allocation for state. 131 132XXH32_sizeofState() is used to know how much space must be allocated for the xxHash 32-bits state. 133Note that the state must be aligned to access 'long long' fields. Memory must be allocated and referenced by a pointer. 134This pointer must then be provided as 'state' into XXH32_resetState(), which initializes the state. 135 136For static allocation purposes (such as allocation on stack, or freestanding systems without malloc()), 137use the structure XXH32_stateSpace_t, which will ensure that memory space is large enough and correctly aligned to access 'long long' fields. 138*/ 139 140 141unsigned int XXH32_intermediateDigest (void* state); 142/* 143This function does the same as XXH32_digest(), generating a 32-bit hash, 144but preserve memory context. 145This way, it becomes possible to generate intermediate hashes, and then continue feeding data with XXH32_update(). 146To free memory context, use XXH32_digest(), or free(). 147*/ 148 149 150 151//**************************** 152// Deprecated function names 153//**************************** 154// The following translations are provided to ease code transition 155// You are encouraged to no longer this function names 156#define XXH32_feed XXH32_update 157#define XXH32_result XXH32_digest 158#define XXH32_getIntermediateResult XXH32_intermediateDigest 159 160 161 162#if defined (__cplusplus) 163} 164#endif 165