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Diffstat (limited to 'third-party/tommyds/tommyhash.h')
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diff --git a/third-party/tommyds/tommyhash.h b/third-party/tommyds/tommyhash.h new file mode 100644 index 0000000..738e33d --- /dev/null +++ b/third-party/tommyds/tommyhash.h @@ -0,0 +1,140 @@ +/* + * Copyright (c) 2010, Andrea Mazzoleni. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. 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. + */ + +/** \file + * Hash functions for the use with ::tommy_hashtable, ::tommy_hashdyn and ::tommy_hashlin. + */ + +#ifndef __TOMMYHASH_H +#define __TOMMYHASH_H + +#include "tommytypes.h" + +/******************************************************************************/ +/* hash */ + +/** + * Hash type used in hashtables. + */ +typedef tommy_key_t tommy_hash_t; + +/** + * Hash function with a 32 bits result. + * Implementation of the Robert Jenkins "lookup3" hash 32 bits version, + * from http://www.burtleburtle.net/bob/hash/doobs.html, function hashlittle(). + * + * This hash is designed to provide a good overall performance in all platforms, + * including 32 bits. If you target only 64 bits, you can use faster hashes, + * like SpookyHash or FarmHash. + * + * \param init_val Initialization value. + * Using a different initialization value, you can generate a completely different set of hash values. + * Use 0 if not relevant. + * \param void_key Pointer to the data to hash. + * \param key_len Size of the data to hash. + * \note + * This function is endianess independent. + * \return The hash value of 32 bits. + */ +tommy_uint32_t tommy_hash_u32(tommy_uint32_t init_val, const void* void_key, tommy_size_t key_len); + +/** + * Hash function with a 64 bits result. + * Implementation of the Robert Jenkins "lookup3" hash 64 bits versions, + * from http://www.burtleburtle.net/bob/hash/doobs.html, function hashlittle2(). + * + * This hash is designed to provide a good overall performance in all platforms, + * including 32 bits. If you target only 64 bits, you can use faster hashes, + * like SpookyHash or FarmHash. + * + * \param init_val Initialization value. + * Using a different initialization value, you can generate a completely different set of hash values. + * Use 0 if not relevant. + * \param void_key Pointer to the data to hash. + * \param key_len Size of the data to hash. + * \note + * This function is endianess independent. + * \return The hash value of 64 bits. + */ +tommy_uint64_t tommy_hash_u64(tommy_uint64_t init_val, const void* void_key, tommy_size_t key_len); + +/** + * String hash function with a 32 bits result. + * Implementation is based on the the Robert Jenkins "lookup3" hash 32 bits version, + * from http://www.burtleburtle.net/bob/hash/doobs.html, function hashlittle(). + * + * This hash is designed to handle strings with an unknown length. If you + * know the string length, the other hash functions are surely faster. + * + * \param init_val Initialization value. + * Using a different initialization value, you can generate a completely different set of hash values. + * Use 0 if not relevant. + * \param void_key Pointer to the string to hash. It has to be 0 terminated. + * \note + * This function is endianess independent. + * \return The hash value of 32 bits. + */ +tommy_uint32_t tommy_strhash_u32(tommy_uint64_t init_val, const void* void_key); + +/** + * Integer reversible hash function for 32 bits. + * Implementation of the Robert Jenkins "4-byte Integer Hashing", + * from http://burtleburtle.net/bob/hash/integer.html + */ +tommy_inline tommy_uint32_t tommy_inthash_u32(tommy_uint32_t key) +{ + key -= key << 6; + key ^= key >> 17; + key -= key << 9; + key ^= key << 4; + key -= key << 3; + key ^= key << 10; + key ^= key >> 15; + + return key; +} + +/** + * Integer reversible hash function for 64 bits. + * Implementation of the Thomas Wang "Integer Hash Function", + * from http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm + */ +tommy_inline tommy_uint64_t tommy_inthash_u64(tommy_uint64_t key) +{ + key = ~key + (key << 21); + key = key ^ (key >> 24); + key = key + (key << 3) + (key << 8); + key = key ^ (key >> 14); + key = key + (key << 2) + (key << 4); + key = key ^ (key >> 28); + key = key + (key << 31); + + return key; +} + +#endif + |