65 lines
1.9 KiB
C
65 lines
1.9 KiB
C
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/* Copyright 2013 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Collection of static dictionary words. */
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#ifndef BROTLI_COMMON_DICTIONARY_H_
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#define BROTLI_COMMON_DICTIONARY_H_
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#include <brotli/port.h>
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#include <brotli/types.h>
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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typedef struct BrotliDictionary {
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/**
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* Number of bits to encode index of dictionary word in a bucket.
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*
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* Specification: Appendix A. Static Dictionary Data
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*
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* Words in a dictionary are bucketed by length.
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* @c 0 means that there are no words of a given length.
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* Dictionary consists of words with length of [4..24] bytes.
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* Values at [0..3] and [25..31] indices should not be addressed.
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*/
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const uint8_t size_bits_by_length[32];
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/* assert(offset[i + 1] == offset[i] + (bits[i] ? (i << bits[i]) : 0)) */
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const uint32_t offsets_by_length[32];
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/* assert(data_size == offsets_by_length[31]) */
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const size_t data_size;
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/* Data array is not bound, and should obey to size_bits_by_length values.
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Specified size matches default (RFC 7932) dictionary. Its size is
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defined by data_size */
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const uint8_t* data;
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} BrotliDictionary;
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BROTLI_COMMON_API extern const BrotliDictionary* BrotliGetDictionary(void);
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/**
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* Sets dictionary data.
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*
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* When dictionary data is already set / present, this method is no-op.
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*
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* Dictionary data MUST be provided before BrotliGetDictionary is invoked.
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* This method is used ONLY in multi-client environment (e.g. C + Java),
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* to reduce storage by sharing single dictionary between implementations.
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*/
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BROTLI_COMMON_API void BrotliSetDictionaryData(const uint8_t* data);
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#define BROTLI_MIN_DICTIONARY_WORD_LENGTH 4
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#define BROTLI_MAX_DICTIONARY_WORD_LENGTH 24
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#if defined(__cplusplus) || defined(c_plusplus)
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} /* extern "C" */
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#endif
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#endif /* BROTLI_COMMON_DICTIONARY_H_ */
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