0afc8bc29a
Summary: Originally: https://github.com/facebook/rocksdb/pull/87/files I'm taking over to apply some finishing touches Test Plan: will add tests Reviewers: dhruba, haobo, sdong, yhchiang, ljin Reviewed By: yhchiang CC: leveldb Differential Revision: https://reviews.facebook.net/D18315
165 lines
6.2 KiB
C
165 lines
6.2 KiB
C
/*
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xxHash - 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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// 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, int len, unsigned int seed);
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/*
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XXH32() :
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Calculate the 32-bits hash of sequence of length "len" stored at memory address "input".
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The memory between input & input+len 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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Note that "len" is type "int", which means it is limited to 2^31-1.
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If your data is larger, use the advanced functions below.
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*/
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//****************************
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// Advanced Hash Functions
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//****************************
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void* XXH32_init (unsigned int seed);
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XXH_errorcode XXH32_update (void* state, const void* input, int len);
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unsigned int XXH32_digest (void* state);
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/*
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These functions calculate the xxhash of an input provided in several small packets,
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as opposed to an input provided as a single block.
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It must be started with :
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void* XXH32_init()
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The function returns a pointer which holds the state of calculation.
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This pointer must be provided as "void* state" parameter for XXH32_update().
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XXH32_update() can be called as many times as necessary.
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The user must provide a valid (allocated) input.
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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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Note that "len" is type "int", which means it is limited to 2^31-1.
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If your data is larger, it is recommended to chunk your data into blocks
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of size for example 2^30 (1GB) to avoid any "int" overflow issue.
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Finally, you can end the calculation anytime, by using XXH32_digest().
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This function returns the final 32-bits hash.
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You must provide the same "void* state" parameter created by XXH32_init().
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Memory will be freed by XXH32_digest().
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*/
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int XXH32_sizeofState();
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XXH_errorcode XXH32_resetState(void* state, unsigned int seed);
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#define XXH32_SIZEOFSTATE 48
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typedef struct { long long ll[(XXH32_SIZEOFSTATE+(sizeof(long long)-1))/sizeof(long long)]; } XXH32_stateSpace_t;
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/*
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These functions allow user application to make its own allocation for state.
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XXH32_sizeofState() is used to know how much space must be allocated for the xxHash 32-bits state.
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Note that the state must be aligned to access 'long long' fields. Memory must be allocated and referenced by a pointer.
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This pointer must then be provided as 'state' into XXH32_resetState(), which initializes the state.
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For static allocation purposes (such as allocation on stack, or freestanding systems without malloc()),
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use the structure XXH32_stateSpace_t, which will ensure that memory space is large enough and correctly aligned to access 'long long' fields.
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*/
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unsigned int XXH32_intermediateDigest (void* state);
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/*
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This function does the same as XXH32_digest(), generating a 32-bit hash,
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but preserve memory context.
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This way, it becomes possible to generate intermediate hashes, and then continue feeding data with XXH32_update().
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To free memory context, use XXH32_digest(), or free().
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*/
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//****************************
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// Deprecated function names
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//****************************
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// The following translations are provided to ease code transition
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// You are encouraged to no longer this function names
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#define XXH32_feed XXH32_update
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#define XXH32_result XXH32_digest
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#define XXH32_getIntermediateResult XXH32_intermediateDigest
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#if defined (__cplusplus)
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}
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#endif
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