IMPORT: hash: import xxhash-r39
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
diff --git a/include/import/xxhash.h b/include/import/xxhash.h
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+/*
+ xxHash - Extremely Fast Hash algorithm
+ Header File
+ Copyright (C) 2012-2014, Yann Collet.
+ BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+ copyright notice, this list of conditions and the following disclaimer
+ in the documentation and/or other materials provided with the
+ distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+ You can contact the author at :
+ - xxHash source repository : http://code.google.com/p/xxhash/
+*/
+
+/* Notice extracted from xxHash homepage :
+
+xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
+It also successfully passes all tests from the SMHasher suite.
+
+Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2 Duo @3GHz)
+
+Name Speed Q.Score Author
+xxHash 5.4 GB/s 10
+CrapWow 3.2 GB/s 2 Andrew
+MumurHash 3a 2.7 GB/s 10 Austin Appleby
+SpookyHash 2.0 GB/s 10 Bob Jenkins
+SBox 1.4 GB/s 9 Bret Mulvey
+Lookup3 1.2 GB/s 9 Bob Jenkins
+SuperFastHash 1.2 GB/s 1 Paul Hsieh
+CityHash64 1.05 GB/s 10 Pike & Alakuijala
+FNV 0.55 GB/s 5 Fowler, Noll, Vo
+CRC32 0.43 GB/s 9
+MD5-32 0.33 GB/s 10 Ronald L. Rivest
+SHA1-32 0.28 GB/s 10
+
+Q.Score is a measure of quality of the hash function.
+It depends on successfully passing SMHasher test set.
+10 is a perfect score.
+*/
+
+#pragma once
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+
+/*****************************
+ Includes
+*****************************/
+#include <stddef.h> /* size_t */
+
+
+/*****************************
+ Type
+*****************************/
+typedef enum { XXH_OK=0, XXH_ERROR } XXH_errorcode;
+
+
+
+/*****************************
+ Simple Hash Functions
+*****************************/
+
+unsigned int XXH32 (const void* input, size_t length, unsigned seed);
+unsigned long long XXH64 (const void* input, size_t length, unsigned long long seed);
+
+/*
+XXH32() :
+ Calculate the 32-bits hash of sequence "length" bytes stored at memory address "input".
+ The memory between input & input+length must be valid (allocated and read-accessible).
+ "seed" can be used to alter the result predictably.
+ This function successfully passes all SMHasher tests.
+ Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
+XXH64() :
+ Calculate the 64-bits hash of sequence of length "len" stored at memory address "input".
+*/
+
+
+
+/*****************************
+ Advanced Hash Functions
+*****************************/
+typedef struct { long long ll[ 6]; } XXH32_state_t;
+typedef struct { long long ll[11]; } XXH64_state_t;
+
+/*
+These structures allow static allocation of XXH states.
+States must then be initialized using XXHnn_reset() before first use.
+
+If you prefer dynamic allocation, please refer to functions below.
+*/
+
+XXH32_state_t* XXH32_createState(void);
+XXH_errorcode XXH32_freeState(XXH32_state_t* statePtr);
+
+XXH64_state_t* XXH64_createState(void);
+XXH_errorcode XXH64_freeState(XXH64_state_t* statePtr);
+
+/*
+These functions create and release memory for XXH state.
+States must then be initialized using XXHnn_reset() before first use.
+*/
+
+
+XXH_errorcode XXH32_reset (XXH32_state_t* statePtr, unsigned seed);
+XXH_errorcode XXH32_update (XXH32_state_t* statePtr, const void* input, size_t length);
+unsigned int XXH32_digest (const XXH32_state_t* statePtr);
+
+XXH_errorcode XXH64_reset (XXH64_state_t* statePtr, unsigned long long seed);
+XXH_errorcode XXH64_update (XXH64_state_t* statePtr, const void* input, size_t length);
+unsigned long long XXH64_digest (const XXH64_state_t* statePtr);
+
+/*
+These functions calculate the xxHash of an input provided in multiple smaller packets,
+as opposed to an input provided as a single block.
+
+XXH state space must first be allocated, using either static or dynamic method provided above.
+
+Start a new hash by initializing state with a seed, using XXHnn_reset().
+
+Then, feed the hash state by calling XXHnn_update() as many times as necessary.
+Obviously, input must be valid, meaning allocated and read accessible.
+The function returns an error code, with 0 meaning OK, and any other value meaning there is an error.
+
+Finally, you can produce a hash anytime, by using XXHnn_digest().
+This function returns the final nn-bits hash.
+You can nonetheless continue feeding the hash state with more input,
+and therefore get some new hashes, by calling again XXHnn_digest().
+
+When you are done, don't forget to free XXH state space, using typically XXHnn_freeState().
+*/
+
+
+#if defined (__cplusplus)
+}
+#endif