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The xxhash library provides a very fast and excellent hash algorithm
suitable for many purposes. It excels at hashing large blocks but is
also extremely fast on small ones. It's distributed under a 2-clause
BSD license (GPL-compatible) so it can be included here. Updates are
distributed here :
https://github.com/Cyan4973/xxHash
157 lines
5.6 KiB
C
157 lines
5.6 KiB
C
/*
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xxHash - Extremely Fast Hash algorithm
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Header File
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Copyright (C) 2012-2014, Yann Collet.
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BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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You can contact the author at :
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- xxHash source repository : http://code.google.com/p/xxhash/
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*/
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/* Notice extracted from xxHash homepage :
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xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
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It also successfully passes all tests from the SMHasher suite.
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Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2 Duo @3GHz)
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Name Speed Q.Score Author
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xxHash 5.4 GB/s 10
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CrapWow 3.2 GB/s 2 Andrew
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MumurHash 3a 2.7 GB/s 10 Austin Appleby
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SpookyHash 2.0 GB/s 10 Bob Jenkins
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SBox 1.4 GB/s 9 Bret Mulvey
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Lookup3 1.2 GB/s 9 Bob Jenkins
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SuperFastHash 1.2 GB/s 1 Paul Hsieh
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CityHash64 1.05 GB/s 10 Pike & Alakuijala
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FNV 0.55 GB/s 5 Fowler, Noll, Vo
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CRC32 0.43 GB/s 9
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MD5-32 0.33 GB/s 10 Ronald L. Rivest
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SHA1-32 0.28 GB/s 10
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Q.Score is a measure of quality of the hash function.
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It depends on successfully passing SMHasher test set.
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10 is a perfect score.
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*/
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#pragma once
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*****************************
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Includes
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*****************************/
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#include <stddef.h> /* size_t */
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/*****************************
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Type
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*****************************/
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typedef enum { XXH_OK=0, XXH_ERROR } XXH_errorcode;
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/*****************************
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Simple Hash Functions
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*****************************/
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unsigned int XXH32 (const void* input, size_t length, unsigned seed);
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unsigned long long XXH64 (const void* input, size_t length, unsigned long long seed);
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/*
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XXH32() :
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Calculate the 32-bits hash of sequence "length" bytes stored at memory address "input".
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The memory between input & input+length must be valid (allocated and read-accessible).
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"seed" can be used to alter the result predictably.
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This function successfully passes all SMHasher tests.
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Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
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XXH64() :
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Calculate the 64-bits hash of sequence of length "len" stored at memory address "input".
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*/
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/*****************************
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Advanced Hash Functions
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*****************************/
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typedef struct { long long ll[ 6]; } XXH32_state_t;
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typedef struct { long long ll[11]; } XXH64_state_t;
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/*
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These structures allow static allocation of XXH states.
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States must then be initialized using XXHnn_reset() before first use.
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If you prefer dynamic allocation, please refer to functions below.
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*/
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XXH32_state_t* XXH32_createState(void);
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XXH_errorcode XXH32_freeState(XXH32_state_t* statePtr);
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XXH64_state_t* XXH64_createState(void);
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XXH_errorcode XXH64_freeState(XXH64_state_t* statePtr);
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/*
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These functions create and release memory for XXH state.
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States must then be initialized using XXHnn_reset() before first use.
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*/
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XXH_errorcode XXH32_reset (XXH32_state_t* statePtr, unsigned seed);
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XXH_errorcode XXH32_update (XXH32_state_t* statePtr, const void* input, size_t length);
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unsigned int XXH32_digest (const XXH32_state_t* statePtr);
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XXH_errorcode XXH64_reset (XXH64_state_t* statePtr, unsigned long long seed);
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XXH_errorcode XXH64_update (XXH64_state_t* statePtr, const void* input, size_t length);
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unsigned long long XXH64_digest (const XXH64_state_t* statePtr);
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/*
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These functions calculate the xxHash of an input provided in multiple smaller packets,
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as opposed to an input provided as a single block.
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XXH state space must first be allocated, using either static or dynamic method provided above.
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Start a new hash by initializing state with a seed, using XXHnn_reset().
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Then, feed the hash state by calling XXHnn_update() as many times as necessary.
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Obviously, input must be valid, meaning allocated and read accessible.
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The function returns an error code, with 0 meaning OK, and any other value meaning there is an error.
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Finally, you can produce a hash anytime, by using XXHnn_digest().
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This function returns the final nn-bits hash.
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You can nonetheless continue feeding the hash state with more input,
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and therefore get some new hashes, by calling again XXHnn_digest().
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When you are done, don't forget to free XXH state space, using typically XXHnn_freeState().
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*/
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#if defined (__cplusplus)
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}
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#endif
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