diff options
Diffstat (limited to 'dependencies/include/libavutil/murmur3.h')
-rw-r--r-- | dependencies/include/libavutil/murmur3.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/dependencies/include/libavutil/murmur3.h b/dependencies/include/libavutil/murmur3.h new file mode 100644 index 0000000..d90bc2f --- /dev/null +++ b/dependencies/include/libavutil/murmur3.h @@ -0,0 +1,115 @@ +/* + * 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 <stddef.h> +#include <stdint.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` + */ +void av_murmur3_update(struct AVMurMur3 *c, const uint8_t *src, size_t len); + +/** + * 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 */ |