MdeModulePkg/Library/BrotliCustomDecompressLib/common/dictionary.h

   1 /* Copyright 2013 Google Inc. All Rights Reserved.
   2
   3    Distributed under MIT license.
   4    See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
   5 */
   6
   7 /* Collection of static dictionary words. */
   8
   9 #ifndef BROTLI_COMMON_DICTIONARY_H_
  10 #define BROTLI_COMMON_DICTIONARY_H_
  11
  12 #include <brotli/port.h>
  13 #include <brotli/types.h>
  14
  15 #if defined(__cplusplus) || defined(c_plusplus)
  16 extern "C" {
  17 #endif
  18
  19 typedef struct BrotliDictionary {
  20   /**
  21    * Number of bits to encode index of dictionary word in a bucket.
  22    *
  23    * Specification: Appendix A. Static Dictionary Data
  24    *
  25    * Words in a dictionary are bucketed by length.
  26    * @c 0 means that there are no words of a given length.
  27    * Dictionary consists of words with length of [4..24] bytes.
  28    * Values at [0..3] and [25..31] indices should not be addressed.
  29    */
  30   uint8_t size_bits_by_length[32];
  31
  32   /* assert(offset[i + 1] == offset[i] + (bits[i] ? (i << bits[i]) : 0)) */
  33   uint32_t offsets_by_length[32];
  34
  35   /* assert(data_size == offsets_by_length[31]) */
  36   size_t data_size;
  37
  38   /* Data array is not bound, and should obey to size_bits_by_length values.
  39      Specified size matches default (RFC 7932) dictionary. Its size is
  40      defined by data_size */
  41   const uint8_t* data;
  42 } BrotliDictionary;
  43
  44 BROTLI_COMMON_API const BrotliDictionary* BrotliGetDictionary(void);
  45
  46 /**
  47  * Sets dictionary data.
  48  *
  49  * When dictionary data is already set / present, this method is no-op.
  50  *
  51  * Dictionary data MUST be provided before BrotliGetDictionary is invoked.
  52  * This method is used ONLY in multi-client environment (e.g. C + Java),
  53  * to reduce storage by sharing single dictionary between implementations.
  54  */
  55 BROTLI_COMMON_API void BrotliSetDictionaryData(const uint8_t* data);
  56
  57 #define BROTLI_MIN_DICTIONARY_WORD_LENGTH 4
  58 #define BROTLI_MAX_DICTIONARY_WORD_LENGTH 24
  59
  60 #if defined(__cplusplus) || defined(c_plusplus)
  61 }  /* extern "C" */
  62 #endif
  63
  64 #endif  /* BROTLI_COMMON_DICTIONARY_H_ */