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6fdb54ddee
Adds a generic hash table with the DXV encoder as an initial use case. Signed-off-by: Emma Worley <emma@emma.gg>
95 lines
2.9 KiB
C
95 lines
2.9 KiB
C
/*
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* Generic hashtable
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* Copyright (C) 2024 Emma Worley <emma@emma.gg>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_HASHTABLE_H
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#define AVCODEC_HASHTABLE_H
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#include <stddef.h>
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/* Implements a hash table using Robin Hood open addressing.
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* See: https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf
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*
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* Keys are placed in the table based on their CRC value and are considered
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* equal when they are bytewise-identical.
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*/
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typedef struct FFHashtableContext FFHashtableContext;
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/**
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* Create a fixed-sized Robin Hood hash table.
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*
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* @param ctx context to allocate and initialize
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* @param key_size size of key type in bytes
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* @param val_size size of value type in bytes
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* @param max_entries maximum number of key-value pairs to store
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*
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* @return zero on success, nonzero on error
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*/
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int ff_hashtable_alloc(struct FFHashtableContext **ctx, size_t key_size, size_t val_size, size_t max_entries);
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/**
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* Look up a value from a hash table given a key.
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*
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* @param ctx hash table context
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* @param key pointer to key data
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* @param val destination pointer for value data
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*
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* @return 1 if the key is found, zero if the key is not found
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*/
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int ff_hashtable_get(const struct FFHashtableContext *ctx, const void *key, void *val);
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/**
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* Store a value in a hash table given a key.
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*
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* @param ctx hash table context
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* @param key pointer to key data
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* @param val pointer for value data
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*
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* @return 1 if the key is written, zero if the key is not written due to the hash table reaching max capacity
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*/
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int ff_hashtable_set(struct FFHashtableContext *ctx, const void *key, const void *val);
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/**
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* Delete a value from a hash table given a key.
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*
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* @param ctx hash table context
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* @param key pointer to key data
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*
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* @return 1 if the key is deleted, zero if the key is not deleted due to not being found
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*/
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int ff_hashtable_delete(struct FFHashtableContext *ctx, const void *key);
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/**
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* Delete all values from a hash table.
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*
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* @param ctx hash table context
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*/
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void ff_hashtable_clear(struct FFHashtableContext *ctx);
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/**
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* Free a hash table.
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*
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* @param ctx hash table context
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*/
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void ff_hashtable_freep(struct FFHashtableContext **ctx);
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#endif
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