/*
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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 hash for ZopfliFindLongestMatch of lz77.c.
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*/
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#ifndef ZOPFLI_HASH_H_
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#define ZOPFLI_HASH_H_
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#include "util.h"
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typedef struct ZopfliHash {
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int* head; /* Hash value to index of its most recent occurance. */
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unsigned short* prev; /* Index to index of prev. occurance of same hash. */
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int* hashval; /* Index to hash value at this index. */
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int val; /* Current hash value. */
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#ifdef ZOPFLI_HASH_SAME_HASH
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/* Fields with similar purpose as the above hash, but for the second hash with
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a value that is calculated differently. */
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int* head2; /* Hash value to index of its most recent occurance. */
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unsigned short* prev2; /* Index to index of prev. occurance of same hash. */
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int* hashval2; /* Index to hash value at this index. */
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int val2; /* Current hash value. */
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#endif
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#ifdef ZOPFLI_HASH_SAME
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unsigned short* same; /* Amount of repetitions of same byte after this .*/
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#endif
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} ZopfliHash;
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/* Allocates and initializes all fields of ZopfliHash. */
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void ZopfliInitHash(size_t window_size, ZopfliHash* h);
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/* Frees all fields of ZopfliHash. */
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void ZopfliCleanHash(ZopfliHash* h);
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/*
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Updates the hash values based on the current position in the array. All calls
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to this must be made for consecutive bytes.
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*/
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void ZopfliUpdateHash(const unsigned char* array, size_t pos, size_t end,
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ZopfliHash* h);
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/*
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Prepopulates hash:
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Fills in the initial values in the hash, before ZopfliUpdateHash can be used
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correctly.
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*/
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void ZopfliWarmupHash(const unsigned char* array, size_t pos, size_t end,
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ZopfliHash* h);
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#endif /* ZOPFLI_HASH_H_ */
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