/* * xxHash - Extremely Fast Hash algorithm * Header File * Copyright (C) 2012-2021 Yann Collet * * BSD 2-Clause License (https://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 homepage: https://www.xxhash.com * - xxHash source repository: https://github.com/Cyan4973/xxHash */ /*! * @mainpage xxHash * * xxHash is an extremely fast non-cryptographic hash algorithm, working at RAM speed * limits. * * It is proposed in four flavors, in three families: * 1. @ref XXH32_family * - Classic 32-bit hash function. Simple, compact, and runs on almost all * 32-bit and 64-bit systems. * 2. @ref XXH64_family * - Classic 64-bit adaptation of XXH32. Just as simple, and runs well on most * 64-bit systems (but _not_ 32-bit systems). * 3. @ref XXH3_family * - Modern 64-bit and 128-bit hash function family which features improved * strength and performance across the board, especially on smaller data. * It benefits greatly from SIMD and 64-bit without requiring it. * * Benchmarks * --- * The reference system uses an Intel i7-9700K CPU, and runs Ubuntu x64 20.04. * The open source benchmark program is compiled with clang v10.0 using -O3 flag. * * | Hash Name | ISA ext | Width | Large Data Speed | Small Data Velocity | * | -------------------- | ------- | ----: | ---------------: | ------------------: | * | XXH3_64bits() | @b AVX2 | 64 | 59.4 GB/s | 133.1 | * | MeowHash | AES-NI | 128 | 58.2 GB/s | 52.5 | * | XXH3_128bits() | @b AVX2 | 128 | 57.9 GB/s | 118.1 | * | CLHash | PCLMUL | 64 | 37.1 GB/s | 58.1 | * | XXH3_64bits() | @b SSE2 | 64 | 31.5 GB/s | 133.1 | * | XXH3_128bits() | @b SSE2 | 128 | 29.6 GB/s | 118.1 | * | RAM sequential read | | N/A | 28.0 GB/s | N/A | * | ahash | AES-NI | 64 | 22.5 GB/s | 107.2 | * | City64 | | 64 | 22.0 GB/s | 76.6 | * | T1ha2 | | 64 | 22.0 GB/s | 99.0 | * | City128 | | 128 | 21.7 GB/s | 57.7 | * | FarmHash | AES-NI | 64 | 21.3 GB/s | 71.9 | * | XXH64() | | 64 | 19.4 GB/s | 71.0 | * | SpookyHash | | 64 | 19.3 GB/s | 53.2 | * | Mum | | 64 | 18.0 GB/s | 67.0 | * | CRC32C | SSE4.2 | 32 | 13.0 GB/s | 57.9 | * | XXH32() | | 32 | 9.7 GB/s | 71.9 | * | City32 | | 32 | 9.1 GB/s | 66.0 | * | Blake3* | @b AVX2 | 256 | 4.4 GB/s | 8.1 | * | Murmur3 | | 32 | 3.9 GB/s | 56.1 | * | SipHash* | | 64 | 3.0 GB/s | 43.2 | * | Blake3* | @b SSE2 | 256 | 2.4 GB/s | 8.1 | * | HighwayHash | | 64 | 1.4 GB/s | 6.0 | * | FNV64 | | 64 | 1.2 GB/s | 62.7 | * | Blake2* | | 256 | 1.1 GB/s | 5.1 | * | SHA1* | | 160 | 0.8 GB/s | 5.6 | * | MD5* | | 128 | 0.6 GB/s | 7.8 | * @note * - Hashes which require a specific ISA extension are noted. SSE2 is also noted, * even though it is mandatory on x64. * - Hashes with an asterisk are cryptographic. Note that MD5 is non-cryptographic * by modern standards. * - Small data velocity is a rough average of algorithm's efficiency for small * data. For more accurate information, see the wiki. * - More benchmarks and strength tests are found on the wiki: * https://github.com/Cyan4973/xxHash/wiki * * Usage * ------ * All xxHash variants use a similar API. Changing the algorithm is a trivial * substitution. * * @pre * For functions which take an input and length parameter, the following * requirements are assumed: * - The range from [`input`, `input + length`) is valid, readable memory. * - The only exception is if the `length` is `0`, `input` may be `NULL`. * - For C++, the objects must have the *TriviallyCopyable* property, as the * functions access bytes directly as if it was an array of `unsigned char`. * * @anchor single_shot_example * **Single Shot** * * These functions are stateless functions which hash a contiguous block of memory, * immediately returning the result. They are the easiest and usually the fastest * option. * * XXH32(), XXH64(), XXH3_64bits(), XXH3_128bits() * * @code{.c} * #include <string.h> * #include "xxhash.h" * * // Example for a function which hashes a null terminated string with XXH32(). * XXH32_hash_t hash_string(const char* string, XXH32_hash_t seed) * { * // NULL pointers are only valid if the length is zero * size_t length = (string == NULL) ? 0 : strlen(string); * return XXH32(string, length, seed); * } * @endcode * * @anchor streaming_example * **Streaming** * * These groups of functions allow incremental hashing of unknown size, even * more than what would fit in a size_t. * * XXH32_reset(), XXH64_reset(), XXH3_64bits_reset(), XXH3_128bits_reset() * * @code{.c} * #include <stdio.h> * #include <assert.h> * #include "xxhash.h" * // Example for a function which hashes a FILE incrementally with XXH3_64bits(). * XXH64_hash_t hashFile(FILE* f) * { * // Allocate a state struct. Do not just use malloc() or new. * XXH3_state_t* state = XXH3_createState(); * assert(state != NULL && "Out of memory!"); * // Reset the state to start a new hashing session. * XXH3_64bits_reset(state); * char buffer[4096]; * size_t count; * // Read the file in chunks * while ((count = fread(buffer, 1, sizeof(buffer), f)) != 0) { * // Run update() as many times as necessary to process the data * XXH3_64bits_update(state, buffer, count); * } * // Retrieve the finalized hash. This will not change the state. * XXH64_hash_t result = XXH3_64bits_digest(state); * // Free the state. Do not use free(). * XXH3_freeState(state); * return result; * } * @endcode * * @file xxhash.h * xxHash prototypes and implementation */ #if defined (__cplusplus) extern … /* extern "C" */ #endif
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