97 lines
3.4 KiB
C++
97 lines
3.4 KiB
C++
/* Copyright 2017 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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/* (Opaque) Shared Dictionary definition and utilities. */
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#ifndef BROTLI_COMMON_SHARED_DICTIONARY_H_
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#define BROTLI_COMMON_SHARED_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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#define SHARED_BROTLI_MIN_DICTIONARY_WORD_LENGTH 4
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#define SHARED_BROTLI_MAX_DICTIONARY_WORD_LENGTH 31
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#define SHARED_BROTLI_NUM_DICTIONARY_CONTEXTS 64
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#define SHARED_BROTLI_MAX_COMPOUND_DICTS 15
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/**
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* Opaque structure that holds shared dictionary data.
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*
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* Allocated and initialized with ::BrotliSharedDictionaryCreateInstance.
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* Cleaned up and deallocated with ::BrotliSharedDictionaryDestroyInstance.
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*/
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typedef struct BrotliSharedDictionaryStruct BrotliSharedDictionary;
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/**
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* Input data type for ::BrotliSharedDictionaryAttach.
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*/
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typedef enum BrotliSharedDictionaryType {
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/** Raw LZ77 prefix dictionary. */
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BROTLI_SHARED_DICTIONARY_RAW = 0,
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/** Serialized shared dictionary. */
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BROTLI_SHARED_DICTIONARY_SERIALIZED = 1
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} BrotliSharedDictionaryType;
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/**
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* Creates an instance of ::BrotliSharedDictionary.
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*
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* Fresh instance has default word dictionary and transforms
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* and no LZ77 prefix dictionary.
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*
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* @p alloc_func and @p free_func @b MUST be both zero or both non-zero. In the
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* case they are both zero, default memory allocators are used. @p opaque is
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* passed to @p alloc_func and @p free_func when they are called. @p free_func
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* has to return without doing anything when asked to free a NULL pointer.
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*
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* @param alloc_func custom memory allocation function
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* @param free_func custom memory free function
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* @param opaque custom memory manager handle
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* @returns @c 0 if instance can not be allocated or initialized
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* @returns pointer to initialized ::BrotliSharedDictionary otherwise
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*/
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BROTLI_COMMON_API BrotliSharedDictionary* BrotliSharedDictionaryCreateInstance(
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brotli_alloc_func alloc_func, brotli_free_func free_func, void* opaque);
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/**
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* Deinitializes and frees ::BrotliSharedDictionary instance.
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*
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* @param dict shared dictionary instance to be cleaned up and deallocated
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*/
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BROTLI_COMMON_API void BrotliSharedDictionaryDestroyInstance(
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BrotliSharedDictionary* dict);
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/**
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* Attaches dictionary to a given instance of ::BrotliSharedDictionary.
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*
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* Dictionary to be attached is represented in a serialized format as a region
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* of memory.
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*
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* Provided data it partially referenced by a resulting (compound) dictionary,
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* and should be kept untouched, while at least one compound dictionary uses it.
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* This way memory overhead is kept minimal by the cost of additional resource
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* management.
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*
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* @param dict dictionary to extend
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* @param type type of dictionary to attach
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* @param data_size size of @p data
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* @param data serialized dictionary of type @p type, with at least @p data_size
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* addressable bytes
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* @returns ::BROTLI_TRUE if provided dictionary is successfully attached
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* @returns ::BROTLI_FALSE otherwise
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*/
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BROTLI_COMMON_API BROTLI_BOOL BrotliSharedDictionaryAttach(
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BrotliSharedDictionary* dict, BrotliSharedDictionaryType type,
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size_t data_size, const uint8_t data[BROTLI_ARRAY_PARAM(data_size)]);
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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_SHARED_DICTIONARY_H_ */
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