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67 lines
2.2 KiB
C
67 lines
2.2 KiB
C
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/*
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Copyright 2011 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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Author: lode.vandevenne@gmail.com (Lode Vandevenne)
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Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
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*/
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/*
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The cache that speeds up ZopfliFindLongestMatch of lz77.c.
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*/
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#ifndef ZOPFLI_CACHE_H_
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#define ZOPFLI_CACHE_H_
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#include "util.h"
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#ifdef ZOPFLI_LONGEST_MATCH_CACHE
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/*
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Cache used by ZopfliFindLongestMatch to remember previously found length/dist
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values.
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This is needed because the squeeze runs will ask these values multiple times for
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the same position.
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Uses large amounts of memory, since it has to remember the distance belonging
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to every possible shorter-than-the-best length (the so called "sublen" array).
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*/
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typedef struct ZopfliLongestMatchCache {
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unsigned short* length;
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unsigned short* dist;
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unsigned char* sublen;
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} ZopfliLongestMatchCache;
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/* Initializes the ZopfliLongestMatchCache. */
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void ZopfliInitCache(size_t blocksize, ZopfliLongestMatchCache* lmc);
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/* Frees up the memory of the ZopfliLongestMatchCache. */
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void ZopfliCleanCache(ZopfliLongestMatchCache* lmc);
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/* Stores sublen array in the cache. */
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void ZopfliSublenToCache(const unsigned short* sublen,
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size_t pos, size_t length,
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ZopfliLongestMatchCache* lmc);
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/* Extracts sublen array from the cache. */
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void ZopfliCacheToSublen(const ZopfliLongestMatchCache* lmc,
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size_t pos, size_t length,
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unsigned short* sublen);
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/* Returns the length up to which could be stored in the cache. */
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unsigned ZopfliMaxCachedSublen(const ZopfliLongestMatchCache* lmc,
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size_t pos, size_t length);
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#endif /* ZOPFLI_LONGEST_MATCH_CACHE */
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#endif /* ZOPFLI_CACHE_H_ */
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