| // Copyright 2014 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Functions to convert brotli-related data structures into the |
| // brotli bit stream. The functions here operate under |
| // assumption that there is enough space in the storage, i.e., there are |
| // no out-of-range checks anywhere. |
| // |
| // These functions do bit addressing into a byte array. The byte array |
| // is called "storage" and the index to the bit is called storage_ix |
| // in function arguments. |
| |
| #ifndef BROTLI_ENC_BROTLI_BIT_STREAM_H_ |
| #define BROTLI_ENC_BROTLI_BIT_STREAM_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| #include <vector> |
| |
| #include "./metablock.h" |
| |
| namespace brotli { |
| |
| // All Store functions here will use a storage_ix, which is always the bit |
| // position for the current storage. |
| |
| // Stores a number between 0 and 255. |
| void StoreVarLenUint8(int n, int* storage_ix, uint8_t* storage); |
| |
| // Stores the compressed meta-block header. |
| bool StoreCompressedMetaBlockHeader(bool final_block, |
| size_t length, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| // Stores the uncompressed meta-block header. |
| bool StoreUncompressedMetaBlockHeader(size_t length, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| // Stores a context map where the histogram type is always the block type. |
| void StoreTrivialContextMap(int num_types, |
| int context_bits, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| void StoreHuffmanTreeOfHuffmanTreeToBitMask( |
| const int num_codes, |
| const uint8_t *code_length_bitdepth, |
| int *storage_ix, |
| uint8_t *storage); |
| |
| // Builds a Huffman tree from histogram[0:length] into depth[0:length] and |
| // bits[0:length] and stores the encoded tree to the bit stream. |
| void BuildAndStoreHuffmanTree(const int *histogram, |
| const int length, |
| const int quality, |
| uint8_t* depth, |
| uint16_t* bits, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| // Encodes the given context map to the bit stream. The number of different |
| // histogram ids is given by num_clusters. |
| void EncodeContextMap(const std::vector<int>& context_map, |
| int num_clusters, |
| int* storage_ix, uint8_t* storage); |
| |
| // Data structure that stores everything that is needed to encode each block |
| // switch command. |
| struct BlockSplitCode { |
| std::vector<int> type_code; |
| std::vector<int> length_prefix; |
| std::vector<int> length_nextra; |
| std::vector<int> length_extra; |
| std::vector<uint8_t> type_depths; |
| std::vector<uint16_t> type_bits; |
| std::vector<uint8_t> length_depths; |
| std::vector<uint16_t> length_bits; |
| }; |
| |
| // Builds a BlockSplitCode data structure from the block split given by the |
| // vector of block types and block lengths and stores it to the bit stream. |
| void BuildAndStoreBlockSplitCode(const std::vector<int>& types, |
| const std::vector<int>& lengths, |
| const int num_types, |
| const int quality, |
| BlockSplitCode* code, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| // Stores the block switch command with index block_ix to the bit stream. |
| void StoreBlockSwitch(const BlockSplitCode& code, |
| const int block_ix, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| bool StoreMetaBlock(const uint8_t* input, |
| size_t start_pos, |
| size_t length, |
| size_t mask, |
| bool final_block, |
| int quality, |
| int num_direct_distance_codes, |
| int distance_postfix_bits, |
| int literal_context_mode, |
| const brotli::Command *commands, |
| size_t n_commands, |
| const MetaBlockSplit& mb, |
| int *storage_ix, |
| uint8_t *storage); |
| |
| // This is for storing uncompressed blocks (simple raw storage of |
| // bytes-as-bytes). |
| bool StoreUncompressedMetaBlock(bool final_block, |
| const uint8_t* input, |
| size_t position, size_t mask, |
| size_t len, |
| int* storage_ix, |
| uint8_t* storage); |
| |
| } // namespace brotli |
| |
| #endif // BROTLI_ENC_BROTLI_BIT_STREAM_H_ |