121 lines
3.5 KiB
C
121 lines
3.5 KiB
C
/*
|
|
* Copyright (C) 2013 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* @ingroup lavu_murmur3
|
|
* Public header for MurmurHash3 hash function implementation.
|
|
*/
|
|
|
|
#ifndef AVUTIL_MURMUR3_H
|
|
#define AVUTIL_MURMUR3_H
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "version.h"
|
|
|
|
/**
|
|
* @defgroup lavu_murmur3 Murmur3
|
|
* @ingroup lavu_hash
|
|
* MurmurHash3 hash function implementation.
|
|
*
|
|
* MurmurHash3 is a non-cryptographic hash function, of which three
|
|
* incompatible versions were created by its inventor Austin Appleby:
|
|
*
|
|
* - 32-bit output
|
|
* - 128-bit output for 32-bit platforms
|
|
* - 128-bit output for 64-bit platforms
|
|
*
|
|
* FFmpeg only implements the last variant: 128-bit output designed for 64-bit
|
|
* platforms. Even though the hash function was designed for 64-bit platforms,
|
|
* the function in reality works on 32-bit systems too, only with reduced
|
|
* performance.
|
|
*
|
|
* @anchor lavu_murmur3_seedinfo
|
|
* By design, MurmurHash3 requires a seed to operate. In response to this,
|
|
* libavutil provides two functions for hash initiation, one that requires a
|
|
* seed (av_murmur3_init_seeded()) and one that uses a fixed arbitrary integer
|
|
* as the seed, and therefore does not (av_murmur3_init()).
|
|
*
|
|
* To make hashes comparable, you should provide the same seed for all calls to
|
|
* this hash function -- if you are supplying one yourself, that is.
|
|
*
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* Allocate an AVMurMur3 hash context.
|
|
*
|
|
* @return Uninitialized hash context or `NULL` in case of error
|
|
*/
|
|
struct AVMurMur3 *av_murmur3_alloc(void);
|
|
|
|
/**
|
|
* Initialize or reinitialize an AVMurMur3 hash context with a seed.
|
|
*
|
|
* @param[out] c Hash context
|
|
* @param[in] seed Random seed
|
|
*
|
|
* @see av_murmur3_init()
|
|
* @see @ref lavu_murmur3_seedinfo "Detailed description" on a discussion of
|
|
* seeds for MurmurHash3.
|
|
*/
|
|
void av_murmur3_init_seeded(struct AVMurMur3 *c, uint64_t seed);
|
|
|
|
/**
|
|
* Initialize or reinitialize an AVMurMur3 hash context.
|
|
*
|
|
* Equivalent to av_murmur3_init_seeded() with a built-in seed.
|
|
*
|
|
* @param[out] c Hash context
|
|
*
|
|
* @see av_murmur3_init_seeded()
|
|
* @see @ref lavu_murmur3_seedinfo "Detailed description" on a discussion of
|
|
* seeds for MurmurHash3.
|
|
*/
|
|
void av_murmur3_init(struct AVMurMur3 *c);
|
|
|
|
/**
|
|
* Update hash context with new data.
|
|
*
|
|
* @param[out] c Hash context
|
|
* @param[in] src Input data to update hash with
|
|
* @param[in] len Number of bytes to read from `src`
|
|
*/
|
|
#if FF_API_CRYPTO_SIZE_T
|
|
void av_murmur3_update(struct AVMurMur3 *c, const uint8_t *src, int len);
|
|
#else
|
|
void av_murmur3_update(struct AVMurMur3 *c, const uint8_t *src, size_t len);
|
|
#endif
|
|
|
|
/**
|
|
* Finish hashing and output digest value.
|
|
*
|
|
* @param[in,out] c Hash context
|
|
* @param[out] dst Buffer where output digest value is stored
|
|
*/
|
|
void av_murmur3_final(struct AVMurMur3 *c, uint8_t dst[16]);
|
|
|
|
/**
|
|
* @}
|
|
*/
|
|
|
|
#endif /* AVUTIL_MURMUR3_H */
|