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/*
* Generic hashtable
* Copyright (C) 2024 Emma Worley <emma@emma.gg>
*
* 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
*/
#ifndef AVCODEC_HASHTABLE_H
#define AVCODEC_HASHTABLE_H
#include <stddef.h>
/* Implements a hash table using Robin Hood open addressing.
* See: https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf
*
* Keys are placed in the table based on their CRC value and are considered
* equal when they are bytewise-identical.
*/
typedef struct FFHashtableContext FFHashtableContext;
/**
* Create a fixed-sized Robin Hood hash table.
*
* @param ctx context to allocate and initialize
* @param key_size size of key type in bytes
* @param val_size size of value type in bytes
* @param max_entries maximum number of key-value pairs to store
*
* @return zero on success, nonzero on error
*/
int ff_hashtable_alloc(struct FFHashtableContext **ctx, size_t key_size, size_t val_size, size_t max_entries);
/**
* Look up a value from a hash table given a key.
*
* @param ctx hash table context
* @param key pointer to key data
* @param val destination pointer for value data
*
* @return 1 if the key is found, zero if the key is not found
*/
int ff_hashtable_get(const struct FFHashtableContext *ctx, const void *key, void *val);
/**
* Store a value in a hash table given a key.
*
* @param ctx hash table context
* @param key pointer to key data
* @param val pointer for value data
*
* @return 1 if the key is written, zero if the key is not written due to the hash table reaching max capacity
*/
int ff_hashtable_set(struct FFHashtableContext *ctx, const void *key, const void *val);
/**
* Delete a value from a hash table given a key.
*
* @param ctx hash table context
* @param key pointer to key data
*
* @return 1 if the key is deleted, zero if the key is not deleted due to not being found
*/
int ff_hashtable_delete(struct FFHashtableContext *ctx, const void *key);
/**
* Delete all values from a hash table.
*
* @param ctx hash table context
*/
void ff_hashtable_clear(struct FFHashtableContext *ctx);
/**
* Free a hash table.
*
* @param ctx hash table context
*/
void ff_hashtable_freep(struct FFHashtableContext **ctx);
#endif
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