/* Copyright 2014 Google Inc. All Rights Reserved. Distributed under MIT license. See file LICENSE for detail or copy at https://opensource.org/licenses/MIT */ /* Brotli bit stream functions to support the low level format. There are no compression algorithms here, just the right ordering of bits to match the specs. */ #include "brotli_bit_stream.h" #include /* memcpy, memset */ #include #include "../common/constants.h" #include "../common/context.h" #include "../common/platform.h" #include "entropy_encode.h" #include "entropy_encode_static.h" #include "fast_log.h" #include "histogram.h" #include "memory.h" #include "write_bits.h" #if defined(__cplusplus) || defined(c_plusplus) extern "C" { #endif #define MAX_HUFFMAN_TREE_SIZE (2 * BROTLI_NUM_COMMAND_SYMBOLS + 1) /* The maximum size of Huffman dictionary for distances assuming that NPOSTFIX = 0 and NDIRECT = 0. */ #define MAX_SIMPLE_DISTANCE_ALPHABET_SIZE \ BROTLI_DISTANCE_ALPHABET_SIZE(0, 0, BROTLI_LARGE_MAX_DISTANCE_BITS) /* MAX_SIMPLE_DISTANCE_ALPHABET_SIZE == 140 */ static BROTLI_INLINE uint32_t BlockLengthPrefixCode(uint32_t len) { uint32_t code = (len >= 177) ? (len >= 753 ? 20 : 14) : (len >= 41 ? 7 : 0); while (code < (BROTLI_NUM_BLOCK_LEN_SYMBOLS - 1) && len >= _kBrotliPrefixCodeRanges[code + 1].offset) ++code; return code; } static BROTLI_INLINE void GetBlockLengthPrefixCode(uint32_t len, size_t* code, uint32_t* n_extra, uint32_t* extra) { *code = BlockLengthPrefixCode(len); *n_extra = _kBrotliPrefixCodeRanges[*code].nbits; *extra = len - _kBrotliPrefixCodeRanges[*code].offset; } typedef struct BlockTypeCodeCalculator { size_t last_type; size_t second_last_type; } BlockTypeCodeCalculator; static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) { self->last_type = 1; self->second_last_type = 0; } static BROTLI_INLINE size_t NextBlockTypeCode( BlockTypeCodeCalculator* calculator, uint8_t type) { size_t type_code = (type == calculator->last_type + 1) ? 1u : (type == calculator->second_last_type) ? 0u : type + 2u; calculator->second_last_type = calculator->last_type; calculator->last_type = type; return type_code; } /* |nibblesbits| represents the 2 bits to encode MNIBBLES (0-3) REQUIRES: length > 0 REQUIRES: length <= (1 << 24) */ static void BrotliEncodeMlen(size_t length, uint64_t* bits, size_t* numbits, uint64_t* nibblesbits) { size_t lg = (length == 1) ? 1 : Log2FloorNonZero((uint32_t)(length - 1)) + 1; size_t mnibbles = (lg < 16 ? 16 : (lg + 3)) / 4; BROTLI_DCHECK(length > 0); BROTLI_DCHECK(length <= (1 << 24)); BROTLI_DCHECK(lg <= 24); *nibblesbits = mnibbles - 4; *numbits = mnibbles * 4; *bits = length - 1; } static BROTLI_INLINE void StoreCommandExtra( const Command* cmd, size_t* storage_ix, uint8_t* storage) { uint32_t copylen_code = CommandCopyLenCode(cmd); uint16_t inscode = GetInsertLengthCode(cmd->insert_len_); uint16_t copycode = GetCopyLengthCode(copylen_code); uint32_t insnumextra = GetInsertExtra(inscode); uint64_t insextraval = cmd->insert_len_ - GetInsertBase(inscode); uint64_t copyextraval = copylen_code - GetCopyBase(copycode); uint64_t bits = (copyextraval << insnumextra) | insextraval; BrotliWriteBits( insnumextra + GetCopyExtra(copycode), bits, storage_ix, storage); } /* Data structure that stores almost everything that is needed to encode each block switch command. */ typedef struct BlockSplitCode { BlockTypeCodeCalculator type_code_calculator; uint8_t type_depths[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; uint16_t type_bits[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; uint8_t length_depths[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; uint16_t length_bits[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; } BlockSplitCode; /* Stores a number between 0 and 255. */ static void StoreVarLenUint8(size_t n, size_t* storage_ix, uint8_t* storage) { if (n == 0) { BrotliWriteBits(1, 0, storage_ix, storage); } else { size_t nbits = Log2FloorNonZero(n); BrotliWriteBits(1, 1, storage_ix, storage); BrotliWriteBits(3, nbits, storage_ix, storage); BrotliWriteBits(nbits, n - ((size_t)1 << nbits), storage_ix, storage); } } /* Stores the compressed meta-block header. REQUIRES: length > 0 REQUIRES: length <= (1 << 24) */ static void StoreCompressedMetaBlockHeader(BROTLI_BOOL is_final_block, size_t length, size_t* storage_ix, uint8_t* storage) { uint64_t lenbits; size_t nlenbits; uint64_t nibblesbits; /* Write ISLAST bit. */ BrotliWriteBits(1, (uint64_t)is_final_block, storage_ix, storage); /* Write ISEMPTY bit. */ if (is_final_block) { BrotliWriteBits(1, 0, storage_ix, storage); } BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); BrotliWriteBits(2, nibblesbits, storage_ix, storage); BrotliWriteBits(nlenbits, lenbits, storage_ix, storage); if (!is_final_block) { /* Write ISUNCOMPRESSED bit. */ BrotliWriteBits(1, 0, storage_ix, storage); } } /* Stores the uncompressed meta-block header. REQUIRES: length > 0 REQUIRES: length <= (1 << 24) */ static void BrotliStoreUncompressedMetaBlockHeader(size_t length, size_t* storage_ix, uint8_t* storage) { uint64_t lenbits; size_t nlenbits; uint64_t nibblesbits; /* Write ISLAST bit. Uncompressed block cannot be the last one, so set to 0. */ BrotliWriteBits(1, 0, storage_ix, storage); BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); BrotliWriteBits(2, nibblesbits, storage_ix, storage); BrotliWriteBits(nlenbits, lenbits, storage_ix, storage); /* Write ISUNCOMPRESSED bit. */ BrotliWriteBits(1, 1, storage_ix, storage); } static void BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask( const int num_codes, const uint8_t* code_length_bitdepth, size_t* storage_ix, uint8_t* storage) { static const uint8_t kStorageOrder[BROTLI_CODE_LENGTH_CODES] = { 1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15 }; /* The bit lengths of the Huffman code over the code length alphabet are compressed with the following static Huffman code: Symbol Code ------ ---- 0 00 1 1110 2 110 3 01 4 10 5 1111 */ static const uint8_t kHuffmanBitLengthHuffmanCodeSymbols[6] = { 0, 7, 3, 2, 1, 15 }; static const uint8_t kHuffmanBitLengthHuffmanCodeBitLengths[6] = { 2, 4, 3, 2, 2, 4 }; size_t skip_some = 0; /* skips none. */ /* Throw away trailing zeros: */ size_t codes_to_store = BROTLI_CODE_LENGTH_CODES; if (num_codes > 1) { for (; codes_to_store > 0; --codes_to_store) { if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) { break; } } } if (code_length_bitdepth[kStorageOrder[0]] == 0 && code_length_bitdepth[kStorageOrder[1]] == 0) { skip_some = 2; /* skips two. */ if (code_length_bitdepth[kStorageOrder[2]] == 0) { skip_some = 3; /* skips three. */ } } BrotliWriteBits(2, skip_some, storage_ix, storage); { size_t i; for (i = skip_some; i < codes_to_store; ++i) { size_t l = code_length_bitdepth[kStorageOrder[i]]; BrotliWriteBits(kHuffmanBitLengthHuffmanCodeBitLengths[l], kHuffmanBitLengthHuffmanCodeSymbols[l], storage_ix, storage); } } } static void BrotliStoreHuffmanTreeToBitMask( const size_t huffman_tree_size, const uint8_t* huffman_tree, const uint8_t* huffman_tree_extra_bits, const uint8_t* code_length_bitdepth, const uint16_t* code_length_bitdepth_symbols, size_t* BROTLI_RESTRICT storage_ix, uint8_t* BROTLI_RESTRICT storage) { size_t i; for (i = 0; i < huffman_tree_size; ++i) { size_t ix = huffman_tree[i]; BrotliWriteBits(code_length_bitdepth[ix], code_length_bitdepth_symbols[ix], storage_ix, storage); /* Extra bits */ switch (ix) { case BROTLI_REPEAT_PREVIOUS_CODE_LENGTH: BrotliWriteBits(2, huffman_tree_extra_bits[i], storage_ix, storage); break; case BROTLI_REPEAT_ZERO_CODE_LENGTH: BrotliWriteBits(3, huffman_tree_extra_bits[i], storage_ix, storage); break; } } } static void StoreSimpleHuffmanTree(const uint8_t* depths, size_t symbols[4], size_t num_symbols, size_t max_bits, size_t* storage_ix, uint8_t* storage) { /* value of 1 indicates a simple Huffman code */ BrotliWriteBits(2, 1, storage_ix, storage); BrotliWriteBits(2, num_symbols - 1, storage_ix, storage); /* NSYM - 1 */ { /* Sort */ size_t i; for (i = 0; i < num_symbols; i++) { size_t j; for (j = i + 1; j < num_symbols; j++) { if (depths[symbols[j]] < depths[symbols[i]]) { BROTLI_SWAP(size_t, symbols, j, i); } } } } if (num_symbols == 2) { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); } else if (num_symbols == 3) { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); } else { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); BrotliWriteBits(max_bits, symbols[3], storage_ix, storage); /* tree-select */ BrotliWriteBits(1, depths[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); } } /* num = alphabet size depths = symbol depths */ void BrotliStoreHuffmanTree(const uint8_t* depths, size_t num, HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) { /* Write the Huffman tree into the brotli-representation. The command alphabet is the largest, so this allocation will fit all alphabets. */ /* TODO(eustas): fix me */ uint8_t huffman_tree[BROTLI_NUM_COMMAND_SYMBOLS]; uint8_t huffman_tree_extra_bits[BROTLI_NUM_COMMAND_SYMBOLS]; size_t huffman_tree_size = 0; uint8_t code_length_bitdepth[BROTLI_CODE_LENGTH_CODES] = { 0 }; uint16_t code_length_bitdepth_symbols[BROTLI_CODE_LENGTH_CODES]; uint32_t huffman_tree_histogram[BROTLI_CODE_LENGTH_CODES] = { 0 }; size_t i; int num_codes = 0; size_t code = 0; BROTLI_DCHECK(num <= BROTLI_NUM_COMMAND_SYMBOLS); BrotliWriteHuffmanTree(depths, num, &huffman_tree_size, huffman_tree, huffman_tree_extra_bits); /* Calculate the statistics of the Huffman tree in brotli-representation. */ for (i = 0; i < huffman_tree_size; ++i) { ++huffman_tree_histogram[huffman_tree[i]]; } for (i = 0; i < BROTLI_CODE_LENGTH_CODES; ++i) { if (huffman_tree_histogram[i]) { if (num_codes == 0) { code = i; num_codes = 1; } else if (num_codes == 1) { num_codes = 2; break; } } } /* Calculate another Huffman tree to use for compressing both the earlier Huffman tree with. */ BrotliCreateHuffmanTree(huffman_tree_histogram, BROTLI_CODE_LENGTH_CODES, 5, tree, code_length_bitdepth); BrotliConvertBitDepthsToSymbols(code_length_bitdepth, BROTLI_CODE_LENGTH_CODES, code_length_bitdepth_symbols); /* Now, we have all the data, let's start storing it */ BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(num_codes, code_length_bitdepth, storage_ix, storage); if (num_codes == 1) { code_length_bitdepth[code] = 0; } /* Store the real Huffman tree now. */ BrotliStoreHuffmanTreeToBitMask(huffman_tree_size, huffman_tree, huffman_tree_extra_bits, code_length_bitdepth, code_length_bitdepth_symbols, storage_ix, 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. */ static void BuildAndStoreHuffmanTree(const uint32_t* histogram, const size_t histogram_length, const size_t alphabet_size, HuffmanTree* tree, uint8_t* depth, uint16_t* bits, size_t* storage_ix, uint8_t* storage) { size_t count = 0; size_t s4[4] = { 0 }; size_t i; size_t max_bits = 0; for (i = 0; i < histogram_length; i++) { if (histogram[i]) { if (count < 4) { s4[count] = i; } else if (count > 4) { break; } count++; } } { size_t max_bits_counter = alphabet_size - 1; while (max_bits_counter) { max_bits_counter >>= 1; ++max_bits; } } if (count <= 1) { BrotliWriteBits(4, 1, storage_ix, storage); BrotliWriteBits(max_bits, s4[0], storage_ix, storage); depth[s4[0]] = 0; bits[s4[0]] = 0; return; } memset(depth, 0, histogram_length * sizeof(depth[0])); BrotliCreateHuffmanTree(histogram, histogram_length, 15, tree, depth); BrotliConvertBitDepthsToSymbols(depth, histogram_length, bits); if (count <= 4) { StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage); } else { BrotliStoreHuffmanTree(depth, histogram_length, tree, storage_ix, storage); } } static BROTLI_INLINE BROTLI_BOOL SortHuffmanTree( const HuffmanTree* v0, const HuffmanTree* v1) { return TO_BROTLI_BOOL(v0->total_count_ < v1->total_count_); } void BrotliBuildAndStoreHuffmanTreeFast(HuffmanTree* tree, const uint32_t* histogram, const size_t histogram_total, const size_t max_bits, uint8_t* depth, uint16_t* bits, size_t* storage_ix, uint8_t* storage) { size_t count = 0; size_t symbols[4] = { 0 }; size_t length = 0; size_t total = histogram_total; while (total != 0) { if (histogram[length]) { if (count < 4) { symbols[count] = length; } ++count; total -= histogram[length]; } ++length; } if (count <= 1) { BrotliWriteBits(4, 1, storage_ix, storage); BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); depth[symbols[0]] = 0; bits[symbols[0]] = 0; return; } memset(depth, 0, length * sizeof(depth[0])); { uint32_t count_limit; for (count_limit = 1; ; count_limit *= 2) { HuffmanTree* node = tree; size_t l; for (l = length; l != 0;) { --l; if (histogram[l]) { if (BROTLI_PREDICT_TRUE(histogram[l] >= count_limit)) { InitHuffmanTree(node, histogram[l], -1, (int16_t)l); } else { InitHuffmanTree(node, count_limit, -1, (int16_t)l); } ++node; } } { const int n = (int)(node - tree); HuffmanTree sentinel; int i = 0; /* Points to the next leaf node. */ int j = n + 1; /* Points to the next non-leaf node. */ int k; SortHuffmanTreeItems(tree, (size_t)n, SortHuffmanTree); /* The nodes are: [0, n): the sorted leaf nodes that we start with. [n]: we add a sentinel here. [n + 1, 2n): new parent nodes are added here, starting from (n+1). These are naturally in ascending order. [2n]: we add a sentinel at the end as well. There will be (2n+1) elements at the end. */ InitHuffmanTree(&sentinel, BROTLI_UINT32_MAX, -1, -1); *node++ = sentinel; *node++ = sentinel; for (k = n - 1; k > 0; --k) { int left, right; if (tree[i].total_count_ <= tree[j].total_count_) { left = i; ++i; } else { left = j; ++j; } if (tree[i].total_count_ <= tree[j].total_count_) { right = i; ++i; } else { right = j; ++j; } /* The sentinel node becomes the parent node. */ node[-1].total_count_ = tree[left].total_count_ + tree[right].total_count_; node[-1].index_left_ = (int16_t)left; node[-1].index_right_or_value_ = (int16_t)right; /* Add back the last sentinel node. */ *node++ = sentinel; } if (BrotliSetDepth(2 * n - 1, tree, depth, 14)) { /* We need to pack the Huffman tree in 14 bits. If this was not successful, add fake entities to the lowest values and retry. */ break; } } } } BrotliConvertBitDepthsToSymbols(depth, length, bits); if (count <= 4) { size_t i; /* value of 1 indicates a simple Huffman code */ BrotliWriteBits(2, 1, storage_ix, storage); BrotliWriteBits(2, count - 1, storage_ix, storage); /* NSYM - 1 */ /* Sort */ for (i = 0; i < count; i++) { size_t j; for (j = i + 1; j < count; j++) { if (depth[symbols[j]] < depth[symbols[i]]) { BROTLI_SWAP(size_t, symbols, j, i); } } } if (count == 2) { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); } else if (count == 3) { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); } else { BrotliWriteBits(max_bits, symbols[0], storage_ix, storage); BrotliWriteBits(max_bits, symbols[1], storage_ix, storage); BrotliWriteBits(max_bits, symbols[2], storage_ix, storage); BrotliWriteBits(max_bits, symbols[3], storage_ix, storage); /* tree-select */ BrotliWriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); } } else { uint8_t previous_value = 8; size_t i; /* Complex Huffman Tree */ StoreStaticCodeLengthCode(storage_ix, storage); /* Actual RLE coding. */ for (i = 0; i < length;) { const uint8_t value = depth[i]; size_t reps = 1; size_t k; for (k = i + 1; k < length && depth[k] == value; ++k) { ++reps; } i += reps; if (value == 0) { BrotliWriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps], storage_ix, storage); } else { if (previous_value != value) { BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], storage_ix, storage); --reps; } if (reps < 3) { while (reps != 0) { reps--; BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], storage_ix, storage); } } else { reps -= 3; BrotliWriteBits(kNonZeroRepsDepth[reps], kNonZeroRepsBits[reps], storage_ix, storage); } previous_value = value; } } } } static size_t IndexOf(const uint8_t* v, size_t v_size, uint8_t value) { size_t i = 0; for (; i < v_size; ++i) { if (v[i] == value) return i; } return i; } static void MoveToFront(uint8_t* v, size_t index) { uint8_t value = v[index]; size_t i; for (i = index; i != 0; --i) { v[i] = v[i - 1]; } v[0] = value; } static void MoveToFrontTransform(const uint32_t* BROTLI_RESTRICT v_in, const size_t v_size, uint32_t* v_out) { size_t i; uint8_t mtf[256]; uint32_t max_value; if (v_size == 0) { return; } max_value = v_in[0]; for (i = 1; i < v_size; ++i) { if (v_in[i] > max_value) max_value = v_in[i]; } BROTLI_DCHECK(max_value < 256u); for (i = 0; i <= max_value; ++i) { mtf[i] = (uint8_t)i; } { size_t mtf_size = max_value + 1; for (i = 0; i < v_size; ++i) { size_t index = IndexOf(mtf, mtf_size, (uint8_t)v_in[i]); BROTLI_DCHECK(index < mtf_size); v_out[i] = (uint32_t)index; MoveToFront(mtf, index); } } } /* Finds runs of zeros in v[0..in_size) and replaces them with a prefix code of the run length plus extra bits (lower 9 bits is the prefix code and the rest are the extra bits). Non-zero values in v[] are shifted by *max_length_prefix. Will not create prefix codes bigger than the initial value of *max_run_length_prefix. The prefix code of run length L is simply Log2Floor(L) and the number of extra bits is the same as the prefix code. */ static void RunLengthCodeZeros(const size_t in_size, uint32_t* BROTLI_RESTRICT v, size_t* BROTLI_RESTRICT out_size, uint32_t* BROTLI_RESTRICT max_run_length_prefix) { uint32_t max_reps = 0; size_t i; uint32_t max_prefix; for (i = 0; i < in_size;) { uint32_t reps = 0; for (; i < in_size && v[i] != 0; ++i) ; for (; i < in_size && v[i] == 0; ++i) { ++reps; } max_reps = BROTLI_MAX(uint32_t, reps, max_reps); } max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0; max_prefix = BROTLI_MIN(uint32_t, max_prefix, *max_run_length_prefix); *max_run_length_prefix = max_prefix; *out_size = 0; for (i = 0; i < in_size;) { BROTLI_DCHECK(*out_size <= i); if (v[i] != 0) { v[*out_size] = v[i] + *max_run_length_prefix; ++i; ++(*out_size); } else { uint32_t reps = 1; size_t k; for (k = i + 1; k < in_size && v[k] == 0; ++k) { ++reps; } i += reps; while (reps != 0) { if (reps < (2u << max_prefix)) { uint32_t run_length_prefix = Log2FloorNonZero(reps); const uint32_t extra_bits = reps - (1u << run_length_prefix); v[*out_size] = run_length_prefix + (extra_bits << 9); ++(*out_size); break; } else { const uint32_t extra_bits = (1u << max_prefix) - 1u; v[*out_size] = max_prefix + (extra_bits << 9); reps -= (2u << max_prefix) - 1u; ++(*out_size); } } } } } #define SYMBOL_BITS 9 typedef struct EncodeContextMapArena { uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS]; } EncodeContextMapArena; static void EncodeContextMap(MemoryManager* m, EncodeContextMapArena* arena, const uint32_t* context_map, size_t context_map_size, size_t num_clusters, HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) { size_t i; uint32_t* rle_symbols; uint32_t max_run_length_prefix = 6; size_t num_rle_symbols = 0; uint32_t* BROTLI_RESTRICT const histogram = arena->histogram; static const uint32_t kSymbolMask = (1u << SYMBOL_BITS) - 1u; uint8_t* BROTLI_RESTRICT const depths = arena->depths; uint16_t* BROTLI_RESTRICT const bits = arena->bits; StoreVarLenUint8(num_clusters - 1, storage_ix, storage); if (num_clusters == 1) { return; } rle_symbols = BROTLI_ALLOC(m, uint32_t, context_map_size); if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(rle_symbols)) return; MoveToFrontTransform(context_map, context_map_size, rle_symbols); RunLengthCodeZeros(context_map_size, rle_symbols, &num_rle_symbols, &max_run_length_prefix); memset(histogram, 0, sizeof(arena->histogram)); for (i = 0; i < num_rle_symbols; ++i) { ++histogram[rle_symbols[i] & kSymbolMask]; } { BROTLI_BOOL use_rle = TO_BROTLI_BOOL(max_run_length_prefix > 0); BrotliWriteBits(1, (uint64_t)use_rle, storage_ix, storage); if (use_rle) { BrotliWriteBits(4, max_run_length_prefix - 1, storage_ix, storage); } } BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix, num_clusters + max_run_length_prefix, tree, depths, bits, storage_ix, storage); for (i = 0; i < num_rle_symbols; ++i) { const uint32_t rle_symbol = rle_symbols[i] & kSymbolMask; const uint32_t extra_bits_val = rle_symbols[i] >> SYMBOL_BITS; BrotliWriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage); if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) { BrotliWriteBits(rle_symbol, extra_bits_val, storage_ix, storage); } } BrotliWriteBits(1, 1, storage_ix, storage); /* use move-to-front */ BROTLI_FREE(m, rle_symbols); } /* Stores the block switch command with index block_ix to the bit stream. */ static BROTLI_INLINE void StoreBlockSwitch(BlockSplitCode* code, const uint32_t block_len, const uint8_t block_type, BROTLI_BOOL is_first_block, size_t* storage_ix, uint8_t* storage) { size_t typecode = NextBlockTypeCode(&code->type_code_calculator, block_type); size_t lencode; uint32_t len_nextra; uint32_t len_extra; if (!is_first_block) { BrotliWriteBits(code->type_depths[typecode], code->type_bits[typecode], storage_ix, storage); } GetBlockLengthPrefixCode(block_len, &lencode, &len_nextra, &len_extra); BrotliWriteBits(code->length_depths[lencode], code->length_bits[lencode], storage_ix, storage); BrotliWriteBits(len_nextra, len_extra, storage_ix, storage); } /* 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. */ static void BuildAndStoreBlockSplitCode(const uint8_t* types, const uint32_t* lengths, const size_t num_blocks, const size_t num_types, HuffmanTree* tree, BlockSplitCode* code, size_t* storage_ix, uint8_t* storage) { uint32_t type_histo[BROTLI_MAX_BLOCK_TYPE_SYMBOLS]; uint32_t length_histo[BROTLI_NUM_BLOCK_LEN_SYMBOLS]; size_t i; BlockTypeCodeCalculator type_code_calculator; memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0])); memset(length_histo, 0, sizeof(length_histo)); InitBlockTypeCodeCalculator(&type_code_calculator); for (i = 0; i < num_blocks; ++i) { size_t type_code = NextBlockTypeCode(&type_code_calculator, types[i]); if (i != 0) ++type_histo[type_code]; ++length_histo[BlockLengthPrefixCode(lengths[i])]; } StoreVarLenUint8(num_types - 1, storage_ix, storage); if (num_types > 1) { /* TODO(eustas): else? could StoreBlockSwitch occur? */ BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, num_types + 2, tree, &code->type_depths[0], &code->type_bits[0], storage_ix, storage); BuildAndStoreHuffmanTree(&length_histo[0], BROTLI_NUM_BLOCK_LEN_SYMBOLS, BROTLI_NUM_BLOCK_LEN_SYMBOLS, tree, &code->length_depths[0], &code->length_bits[0], storage_ix, storage); StoreBlockSwitch(code, lengths[0], types[0], 1, storage_ix, storage); } } /* Stores a context map where the histogram type is always the block type. */ static void StoreTrivialContextMap(EncodeContextMapArena* arena, size_t num_types, size_t context_bits, HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) { StoreVarLenUint8(num_types - 1, storage_ix, storage); if (num_types > 1) { size_t repeat_code = context_bits - 1u; size_t repeat_bits = (1u << repeat_code) - 1u; size_t alphabet_size = num_types + repeat_code; uint32_t* BROTLI_RESTRICT const histogram = arena->histogram; uint8_t* BROTLI_RESTRICT const depths = arena->depths; uint16_t* BROTLI_RESTRICT const bits = arena->bits; size_t i; memset(histogram, 0, alphabet_size * sizeof(histogram[0])); /* Write RLEMAX. */ BrotliWriteBits(1, 1, storage_ix, storage); BrotliWriteBits(4, repeat_code - 1, storage_ix, storage); histogram[repeat_code] = (uint32_t)num_types; histogram[0] = 1; for (i = context_bits; i < alphabet_size; ++i) { histogram[i] = 1; } BuildAndStoreHuffmanTree(histogram, alphabet_size, alphabet_size, tree, depths, bits, storage_ix, storage); for (i = 0; i < num_types; ++i) { size_t code = (i == 0 ? 0 : i + context_bits - 1); BrotliWriteBits(depths[code], bits[code], storage_ix, storage); BrotliWriteBits( depths[repeat_code], bits[repeat_code], storage_ix, storage); BrotliWriteBits(repeat_code, repeat_bits, storage_ix, storage); } /* Write IMTF (inverse-move-to-front) bit. */ BrotliWriteBits(1, 1, storage_ix, storage); } } /* Manages the encoding of one block category (literal, command or distance). */ typedef struct BlockEncoder { size_t histogram_length_; size_t num_block_types_; const uint8_t* block_types_; /* Not owned. */ const uint32_t* block_lengths_; /* Not owned. */ size_t num_blocks_; BlockSplitCode block_split_code_; size_t block_ix_; size_t block_len_; size_t entropy_ix_; uint8_t* depths_; uint16_t* bits_; } BlockEncoder; static void InitBlockEncoder(BlockEncoder* self, size_t histogram_length, size_t num_block_types, const uint8_t* block_types, const uint32_t* block_lengths, const size_t num_blocks) { self->histogram_length_ = histogram_length; self->num_block_types_ = num_block_types; self->block_types_ = block_types; self->block_lengths_ = block_lengths; self->num_blocks_ = num_blocks; InitBlockTypeCodeCalculator(&self->block_split_code_.type_code_calculator); self->block_ix_ = 0; self->block_len_ = num_blocks == 0 ? 0 : block_lengths[0]; self->entropy_ix_ = 0; self->depths_ = 0; self->bits_ = 0; } static void CleanupBlockEncoder(MemoryManager* m, BlockEncoder* self) { BROTLI_FREE(m, self->depths_); BROTLI_FREE(m, self->bits_); } /* Creates entropy codes of block lengths and block types and stores them to the bit stream. */ static void BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder* self, HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) { BuildAndStoreBlockSplitCode(self->block_types_, self->block_lengths_, self->num_blocks_, self->num_block_types_, tree, &self->block_split_code_, storage_ix, storage); } /* Stores the next symbol with the entropy code of the current block type. Updates the block type and block length at block boundaries. */ static void StoreSymbol(BlockEncoder* self, size_t symbol, size_t* storage_ix, uint8_t* storage) { if (self->block_len_ == 0) { size_t block_ix = ++self->block_ix_; uint32_t block_len = self->block_lengths_[block_ix]; uint8_t block_type = self->block_types_[block_ix]; self->block_len_ = block_len; self->entropy_ix_ = block_type * self->histogram_length_; StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0, storage_ix, storage); } --self->block_len_; { size_t ix = self->entropy_ix_ + symbol; BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage); } } /* Stores the next symbol with the entropy code of the current block type and context value. Updates the block type and block length at block boundaries. */ static void StoreSymbolWithContext(BlockEncoder* self, size_t symbol, size_t context, const uint32_t* context_map, size_t* storage_ix, uint8_t* storage, const size_t context_bits) { if (self->block_len_ == 0) { size_t block_ix = ++self->block_ix_; uint32_t block_len = self->block_lengths_[block_ix]; uint8_t block_type = self->block_types_[block_ix]; self->block_len_ = block_len; self->entropy_ix_ = (size_t)block_type << context_bits; StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0, storage_ix, storage); } --self->block_len_; { size_t histo_ix = context_map[self->entropy_ix_ + context]; size_t ix = histo_ix * self->histogram_length_ + symbol; BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage); } } #define FN(X) X ## Literal /* NOLINTNEXTLINE(build/include) */ #include "block_encoder_inc.h" #undef FN #define FN(X) X ## Command /* NOLINTNEXTLINE(build/include) */ #include "block_encoder_inc.h" #undef FN #define FN(X) X ## Distance /* NOLINTNEXTLINE(build/include) */ #include "block_encoder_inc.h" #undef FN static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) { *storage_ix = (*storage_ix + 7u) & ~7u; storage[*storage_ix >> 3] = 0; } typedef struct StoreMetablockArena { BlockEncoder literal_enc; BlockEncoder command_enc; BlockEncoder distance_enc; EncodeContextMapArena context_map_arena; } StoreMetablockArena; void BrotliStoreMetaBlock(MemoryManager* m, const uint8_t* input, size_t start_pos, size_t length, size_t mask, uint8_t prev_byte, uint8_t prev_byte2, BROTLI_BOOL is_last, const BrotliEncoderParams* params, ContextType literal_context_mode, const Command* commands, size_t n_commands, const MetaBlockSplit* mb, size_t* storage_ix, uint8_t* storage) { size_t pos = start_pos; size_t i; uint32_t num_distance_symbols = params->dist.alphabet_size_max; uint32_t num_effective_distance_symbols = params->dist.alphabet_size_limit; HuffmanTree* tree; ContextLut literal_context_lut = BROTLI_CONTEXT_LUT(literal_context_mode); StoreMetablockArena* arena = NULL; BlockEncoder* literal_enc = NULL; BlockEncoder* command_enc = NULL; BlockEncoder* distance_enc = NULL; const BrotliDistanceParams* dist = ¶ms->dist; BROTLI_DCHECK( num_effective_distance_symbols <= BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS); StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE); arena = BROTLI_ALLOC(m, StoreMetablockArena, 1); if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(tree) || BROTLI_IS_NULL(arena)) return; literal_enc = &arena->literal_enc; command_enc = &arena->command_enc; distance_enc = &arena->distance_enc; InitBlockEncoder(literal_enc, BROTLI_NUM_LITERAL_SYMBOLS, mb->literal_split.num_types, mb->literal_split.types, mb->literal_split.lengths, mb->literal_split.num_blocks); InitBlockEncoder(command_enc, BROTLI_NUM_COMMAND_SYMBOLS, mb->command_split.num_types, mb->command_split.types, mb->command_split.lengths, mb->command_split.num_blocks); InitBlockEncoder(distance_enc, num_effective_distance_symbols, mb->distance_split.num_types, mb->distance_split.types, mb->distance_split.lengths, mb->distance_split.num_blocks); BuildAndStoreBlockSwitchEntropyCodes(literal_enc, tree, storage_ix, storage); BuildAndStoreBlockSwitchEntropyCodes(command_enc, tree, storage_ix, storage); BuildAndStoreBlockSwitchEntropyCodes(distance_enc, tree, storage_ix, storage); BrotliWriteBits(2, dist->distance_postfix_bits, storage_ix, storage); BrotliWriteBits( 4, dist->num_direct_distance_codes >> dist->distance_postfix_bits, storage_ix, storage); for (i = 0; i < mb->literal_split.num_types; ++i) { BrotliWriteBits(2, literal_context_mode, storage_ix, storage); } if (mb->literal_context_map_size == 0) { StoreTrivialContextMap( &arena->context_map_arena, mb->literal_histograms_size, BROTLI_LITERAL_CONTEXT_BITS, tree, storage_ix, storage); } else { EncodeContextMap(m, &arena->context_map_arena, mb->literal_context_map, mb->literal_context_map_size, mb->literal_histograms_size, tree, storage_ix, storage); if (BROTLI_IS_OOM(m)) return; } if (mb->distance_context_map_size == 0) { StoreTrivialContextMap( &arena->context_map_arena, mb->distance_histograms_size, BROTLI_DISTANCE_CONTEXT_BITS, tree, storage_ix, storage); } else { EncodeContextMap(m, &arena->context_map_arena, mb->distance_context_map, mb->distance_context_map_size, mb->distance_histograms_size, tree, storage_ix, storage); if (BROTLI_IS_OOM(m)) return; } BuildAndStoreEntropyCodesLiteral(m, literal_enc, mb->literal_histograms, mb->literal_histograms_size, BROTLI_NUM_LITERAL_SYMBOLS, tree, storage_ix, storage); if (BROTLI_IS_OOM(m)) return; BuildAndStoreEntropyCodesCommand(m, command_enc, mb->command_histograms, mb->command_histograms_size, BROTLI_NUM_COMMAND_SYMBOLS, tree, storage_ix, storage); if (BROTLI_IS_OOM(m)) return; BuildAndStoreEntropyCodesDistance(m, distance_enc, mb->distance_histograms, mb->distance_histograms_size, num_distance_symbols, tree, storage_ix, storage); if (BROTLI_IS_OOM(m)) return; BROTLI_FREE(m, tree); for (i = 0; i < n_commands; ++i) { const Command cmd = commands[i]; size_t cmd_code = cmd.cmd_prefix_; StoreSymbol(command_enc, cmd_code, storage_ix, storage); StoreCommandExtra(&cmd, storage_ix, storage); if (mb->literal_context_map_size == 0) { size_t j; for (j = cmd.insert_len_; j != 0; --j) { StoreSymbol(literal_enc, input[pos & mask], storage_ix, storage); ++pos; } } else { size_t j; for (j = cmd.insert_len_; j != 0; --j) { size_t context = BROTLI_CONTEXT(prev_byte, prev_byte2, literal_context_lut); uint8_t literal = input[pos & mask]; StoreSymbolWithContext(literal_enc, literal, context, mb->literal_context_map, storage_ix, storage, BROTLI_LITERAL_CONTEXT_BITS); prev_byte2 = prev_byte; prev_byte = literal; ++pos; } } pos += CommandCopyLen(&cmd); if (CommandCopyLen(&cmd)) { prev_byte2 = input[(pos - 2) & mask]; prev_byte = input[(pos - 1) & mask]; if (cmd.cmd_prefix_ >= 128) { size_t dist_code = cmd.dist_prefix_ & 0x3FF; uint32_t distnumextra = cmd.dist_prefix_ >> 10; uint64_t distextra = cmd.dist_extra_; if (mb->distance_context_map_size == 0) { StoreSymbol(distance_enc, dist_code, storage_ix, storage); } else { size_t context = CommandDistanceContext(&cmd); StoreSymbolWithContext(distance_enc, dist_code, context, mb->distance_context_map, storage_ix, storage, BROTLI_DISTANCE_CONTEXT_BITS); } BrotliWriteBits(distnumextra, distextra, storage_ix, storage); } } } CleanupBlockEncoder(m, distance_enc); CleanupBlockEncoder(m, command_enc); CleanupBlockEncoder(m, literal_enc); BROTLI_FREE(m, arena); if (is_last) { JumpToByteBoundary(storage_ix, storage); } } static void BuildHistograms(const uint8_t* input, size_t start_pos, size_t mask, const Command* commands, size_t n_commands, HistogramLiteral* lit_histo, HistogramCommand* cmd_histo, HistogramDistance* dist_histo) { size_t pos = start_pos; size_t i; for (i = 0; i < n_commands; ++i) { const Command cmd = commands[i]; size_t j; HistogramAddCommand(cmd_histo, cmd.cmd_prefix_); for (j = cmd.insert_len_; j != 0; --j) { HistogramAddLiteral(lit_histo, input[pos & mask]); ++pos; } pos += CommandCopyLen(&cmd); if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) { HistogramAddDistance(dist_histo, cmd.dist_prefix_ & 0x3FF); } } } static void StoreDataWithHuffmanCodes(const uint8_t* input, size_t start_pos, size_t mask, const Command* commands, size_t n_commands, const uint8_t* lit_depth, const uint16_t* lit_bits, const uint8_t* cmd_depth, const uint16_t* cmd_bits, const uint8_t* dist_depth, const uint16_t* dist_bits, size_t* storage_ix, uint8_t* storage) { size_t pos = start_pos; size_t i; for (i = 0; i < n_commands; ++i) { const Command cmd = commands[i]; const size_t cmd_code = cmd.cmd_prefix_; size_t j; BrotliWriteBits( cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage); StoreCommandExtra(&cmd, storage_ix, storage); for (j = cmd.insert_len_; j != 0; --j) { const uint8_t literal = input[pos & mask]; BrotliWriteBits( lit_depth[literal], lit_bits[literal], storage_ix, storage); ++pos; } pos += CommandCopyLen(&cmd); if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) { const size_t dist_code = cmd.dist_prefix_ & 0x3FF; const uint32_t distnumextra = cmd.dist_prefix_ >> 10; const uint32_t distextra = cmd.dist_extra_; BrotliWriteBits(dist_depth[dist_code], dist_bits[dist_code], storage_ix, storage); BrotliWriteBits(distnumextra, distextra, storage_ix, storage); } } } /* TODO(eustas): pull alloc/dealloc to caller? */ typedef struct MetablockArena { HistogramLiteral lit_histo; HistogramCommand cmd_histo; HistogramDistance dist_histo; /* TODO(eustas): merge bits and depth? */ uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS]; uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS]; uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS]; uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS]; uint8_t dist_depth[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE]; uint16_t dist_bits[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE]; HuffmanTree tree[MAX_HUFFMAN_TREE_SIZE]; } MetablockArena; void BrotliStoreMetaBlockTrivial(MemoryManager* m, const uint8_t* input, size_t start_pos, size_t length, size_t mask, BROTLI_BOOL is_last, const BrotliEncoderParams* params, const Command* commands, size_t n_commands, size_t* storage_ix, uint8_t* storage) { MetablockArena* arena = BROTLI_ALLOC(m, MetablockArena, 1); uint32_t num_distance_symbols = params->dist.alphabet_size_max; if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(arena)) return; StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); HistogramClearLiteral(&arena->lit_histo); HistogramClearCommand(&arena->cmd_histo); HistogramClearDistance(&arena->dist_histo); BuildHistograms(input, start_pos, mask, commands, n_commands, &arena->lit_histo, &arena->cmd_histo, &arena->dist_histo); BrotliWriteBits(13, 0, storage_ix, storage); BuildAndStoreHuffmanTree(arena->lit_histo.data_, BROTLI_NUM_LITERAL_SYMBOLS, BROTLI_NUM_LITERAL_SYMBOLS, arena->tree, arena->lit_depth, arena->lit_bits, storage_ix, storage); BuildAndStoreHuffmanTree(arena->cmd_histo.data_, BROTLI_NUM_COMMAND_SYMBOLS, BROTLI_NUM_COMMAND_SYMBOLS, arena->tree, arena->cmd_depth, arena->cmd_bits, storage_ix, storage); BuildAndStoreHuffmanTree(arena->dist_histo.data_, MAX_SIMPLE_DISTANCE_ALPHABET_SIZE, num_distance_symbols, arena->tree, arena->dist_depth, arena->dist_bits, storage_ix, storage); StoreDataWithHuffmanCodes(input, start_pos, mask, commands, n_commands, arena->lit_depth, arena->lit_bits, arena->cmd_depth, arena->cmd_bits, arena->dist_depth, arena->dist_bits, storage_ix, storage); BROTLI_FREE(m, arena); if (is_last) { JumpToByteBoundary(storage_ix, storage); } } void BrotliStoreMetaBlockFast(MemoryManager* m, const uint8_t* input, size_t start_pos, size_t length, size_t mask, BROTLI_BOOL is_last, const BrotliEncoderParams* params, const Command* commands, size_t n_commands, size_t* storage_ix, uint8_t* storage) { MetablockArena* arena = BROTLI_ALLOC(m, MetablockArena, 1); uint32_t num_distance_symbols = params->dist.alphabet_size_max; uint32_t distance_alphabet_bits = Log2FloorNonZero(num_distance_symbols - 1) + 1; if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(arena)) return; StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); BrotliWriteBits(13, 0, storage_ix, storage); if (n_commands <= 128) { uint32_t histogram[BROTLI_NUM_LITERAL_SYMBOLS] = { 0 }; size_t pos = start_pos; size_t num_literals = 0; size_t i; for (i = 0; i < n_commands; ++i) { const Command cmd = commands[i]; size_t j; for (j = cmd.insert_len_; j != 0; --j) { ++histogram[input[pos & mask]]; ++pos; } num_literals += cmd.insert_len_; pos += CommandCopyLen(&cmd); } BrotliBuildAndStoreHuffmanTreeFast(arena->tree, histogram, num_literals, /* max_bits = */ 8, arena->lit_depth, arena->lit_bits, storage_ix, storage); StoreStaticCommandHuffmanTree(storage_ix, storage); StoreStaticDistanceHuffmanTree(storage_ix, storage); StoreDataWithHuffmanCodes(input, start_pos, mask, commands, n_commands, arena->lit_depth, arena->lit_bits, kStaticCommandCodeDepth, kStaticCommandCodeBits, kStaticDistanceCodeDepth, kStaticDistanceCodeBits, storage_ix, storage); } else { HistogramClearLiteral(&arena->lit_histo); HistogramClearCommand(&arena->cmd_histo); HistogramClearDistance(&arena->dist_histo); BuildHistograms(input, start_pos, mask, commands, n_commands, &arena->lit_histo, &arena->cmd_histo, &arena->dist_histo); BrotliBuildAndStoreHuffmanTreeFast(arena->tree, arena->lit_histo.data_, arena->lit_histo.total_count_, /* max_bits = */ 8, arena->lit_depth, arena->lit_bits, storage_ix, storage); BrotliBuildAndStoreHuffmanTreeFast(arena->tree, arena->cmd_histo.data_, arena->cmd_histo.total_count_, /* max_bits = */ 10, arena->cmd_depth, arena->cmd_bits, storage_ix, storage); BrotliBuildAndStoreHuffmanTreeFast(arena->tree, arena->dist_histo.data_, arena->dist_histo.total_count_, /* max_bits = */ distance_alphabet_bits, arena->dist_depth, arena->dist_bits, storage_ix, storage); StoreDataWithHuffmanCodes(input, start_pos, mask, commands, n_commands, arena->lit_depth, arena->lit_bits, arena->cmd_depth, arena->cmd_bits, arena->dist_depth, arena->dist_bits, storage_ix, storage); } BROTLI_FREE(m, arena); if (is_last) { JumpToByteBoundary(storage_ix, storage); } } /* This is for storing uncompressed blocks (simple raw storage of bytes-as-bytes). */ void BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block, const uint8_t* BROTLI_RESTRICT input, size_t position, size_t mask, size_t len, size_t* BROTLI_RESTRICT storage_ix, uint8_t* BROTLI_RESTRICT storage) { size_t masked_pos = position & mask; BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage); JumpToByteBoundary(storage_ix, storage); if (masked_pos + len > mask + 1) { size_t len1 = mask + 1 - masked_pos; memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len1); *storage_ix += len1 << 3; len -= len1; masked_pos = 0; } memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len); *storage_ix += len << 3; /* We need to clear the next 4 bytes to continue to be compatible with BrotliWriteBits. */ BrotliWriteBitsPrepareStorage(*storage_ix, storage); /* Since the uncompressed block itself may not be the final block, add an empty one after this. */ if (is_final_block) { BrotliWriteBits(1, 1, storage_ix, storage); /* islast */ BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */ JumpToByteBoundary(storage_ix, storage); } } #if defined(BROTLI_TEST) void GetBlockLengthPrefixCodeForTest(uint32_t len, size_t* code, uint32_t* n_extra, uint32_t* extra) { GetBlockLengthPrefixCode(len, code, n_extra, extra); } #endif #if defined(__cplusplus) || defined(c_plusplus) } /* extern "C" */ #endif