diff options
Diffstat (limited to 'thirdparty/brotli/enc/brotli_bit_stream.cc')
| -rw-r--r-- | thirdparty/brotli/enc/brotli_bit_stream.cc | 1181 |
1 files changed, 0 insertions, 1181 deletions
diff --git a/thirdparty/brotli/enc/brotli_bit_stream.cc b/thirdparty/brotli/enc/brotli_bit_stream.cc deleted file mode 100644 index 43f12107..00000000 --- a/thirdparty/brotli/enc/brotli_bit_stream.cc +++ /dev/null @@ -1,1181 +0,0 @@ -/* 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 <algorithm> -#include <cstdlib> /* free, malloc */ -#include <cstring> -#include <limits> -#include <vector> - -#include "./bit_cost.h" -#include "./context.h" -#include "./entropy_encode.h" -#include "./entropy_encode_static.h" -#include "./fast_log.h" -#include "./prefix.h" -#include "./write_bits.h" - -namespace brotli { - -namespace { - -static const size_t kMaxHuffmanTreeSize = 2 * kNumCommandPrefixes + 1; -// Context map alphabet has 256 context id symbols plus max 16 rle symbols. -static const size_t kContextMapAlphabetSize = 256 + 16; -// Block type alphabet has 256 block id symbols plus 2 special symbols. -static const size_t kBlockTypeAlphabetSize = 256 + 2; - -// nibblesbits represents the 2 bits to encode MNIBBLES (0-3) -// REQUIRES: length > 0 -// REQUIRES: length <= (1 << 24) -void EncodeMlen(size_t length, uint64_t* bits, - size_t* numbits, uint64_t* nibblesbits) { - assert(length > 0); - assert(length <= (1 << 24)); - length--; // MLEN - 1 is encoded - size_t lg = length == 0 ? 1 : Log2FloorNonZero( - static_cast<uint32_t>(length)) + 1; - assert(lg <= 24); - size_t mnibbles = (lg < 16 ? 16 : (lg + 3)) / 4; - *nibblesbits = mnibbles - 4; - *numbits = mnibbles * 4; - *bits = length; -} - -static inline void StoreCommandExtra( - const Command& cmd, size_t* storage_ix, uint8_t* storage) { - uint32_t copylen_code = cmd.copy_len_code(); - 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; - WriteBits(insnumextra + GetCopyExtra(copycode), bits, storage_ix, storage); -} - -} // namespace - -void StoreVarLenUint8(size_t n, size_t* storage_ix, uint8_t* storage) { - if (n == 0) { - WriteBits(1, 0, storage_ix, storage); - } else { - WriteBits(1, 1, storage_ix, storage); - size_t nbits = Log2FloorNonZero(n); - WriteBits(3, nbits, storage_ix, storage); - WriteBits(nbits, n - (1 << nbits), storage_ix, storage); - } -} - -void StoreCompressedMetaBlockHeader(bool final_block, - size_t length, - size_t* storage_ix, - uint8_t* storage) { - // Write ISLAST bit. - WriteBits(1, final_block, storage_ix, storage); - // Write ISEMPTY bit. - if (final_block) { - WriteBits(1, 0, storage_ix, storage); - } - - uint64_t lenbits; - size_t nlenbits; - uint64_t nibblesbits; - EncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); - WriteBits(2, nibblesbits, storage_ix, storage); - WriteBits(nlenbits, lenbits, storage_ix, storage); - - if (!final_block) { - // Write ISUNCOMPRESSED bit. - WriteBits(1, 0, storage_ix, storage); - } -} - -void StoreUncompressedMetaBlockHeader(size_t length, - size_t* storage_ix, - uint8_t* storage) { - // Write ISLAST bit. Uncompressed block cannot be the last one, so set to 0. - WriteBits(1, 0, storage_ix, storage); - uint64_t lenbits; - size_t nlenbits; - uint64_t nibblesbits; - EncodeMlen(length, &lenbits, &nlenbits, &nibblesbits); - WriteBits(2, nibblesbits, storage_ix, storage); - WriteBits(nlenbits, lenbits, storage_ix, storage); - // Write ISUNCOMPRESSED bit. - WriteBits(1, 1, storage_ix, storage); -} - -void StoreHuffmanTreeOfHuffmanTreeToBitMask( - const int num_codes, - const uint8_t *code_length_bitdepth, - size_t *storage_ix, - uint8_t *storage) { - static const uint8_t kStorageOrder[kCodeLengthCodes] = { - 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 - }; - - // Throw away trailing zeros: - size_t codes_to_store = kCodeLengthCodes; - if (num_codes > 1) { - for (; codes_to_store > 0; --codes_to_store) { - if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) { - break; - } - } - } - size_t skip_some = 0; // skips none. - 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. - } - } - WriteBits(2, skip_some, storage_ix, storage); - for (size_t i = skip_some; i < codes_to_store; ++i) { - size_t l = code_length_bitdepth[kStorageOrder[i]]; - WriteBits(kHuffmanBitLengthHuffmanCodeBitLengths[l], - kHuffmanBitLengthHuffmanCodeSymbols[l], storage_ix, storage); - } -} - -static void StoreHuffmanTreeToBitMask( - 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 * __restrict storage_ix, - uint8_t * __restrict storage) { - for (size_t i = 0; i < huffman_tree_size; ++i) { - size_t ix = huffman_tree[i]; - WriteBits(code_length_bitdepth[ix], code_length_bitdepth_symbols[ix], - storage_ix, storage); - // Extra bits - switch (ix) { - case 16: - WriteBits(2, huffman_tree_extra_bits[i], storage_ix, storage); - break; - case 17: - WriteBits(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 - WriteBits(2, 1, storage_ix, storage); - WriteBits(2, num_symbols - 1, storage_ix, storage); // NSYM - 1 - - // Sort - for (size_t i = 0; i < num_symbols; i++) { - for (size_t j = i + 1; j < num_symbols; j++) { - if (depths[symbols[j]] < depths[symbols[i]]) { - std::swap(symbols[j], symbols[i]); - } - } - } - - if (num_symbols == 2) { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - } else if (num_symbols == 3) { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - WriteBits(max_bits, symbols[2], storage_ix, storage); - } else { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - WriteBits(max_bits, symbols[2], storage_ix, storage); - WriteBits(max_bits, symbols[3], storage_ix, storage); - // tree-select - WriteBits(1, depths[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); - } -} - -// num = alphabet size -// depths = symbol depths -void StoreHuffmanTree(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. - assert(num <= kNumCommandPrefixes); - uint8_t huffman_tree[kNumCommandPrefixes]; - uint8_t huffman_tree_extra_bits[kNumCommandPrefixes]; - size_t huffman_tree_size = 0; - WriteHuffmanTree(depths, num, &huffman_tree_size, huffman_tree, - huffman_tree_extra_bits); - - // Calculate the statistics of the Huffman tree in brotli-representation. - uint32_t huffman_tree_histogram[kCodeLengthCodes] = { 0 }; - for (size_t i = 0; i < huffman_tree_size; ++i) { - ++huffman_tree_histogram[huffman_tree[i]]; - } - - int num_codes = 0; - int code = 0; - for (int i = 0; i < kCodeLengthCodes; ++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. - uint8_t code_length_bitdepth[kCodeLengthCodes] = { 0 }; - uint16_t code_length_bitdepth_symbols[kCodeLengthCodes] = { 0 }; - CreateHuffmanTree(&huffman_tree_histogram[0], kCodeLengthCodes, - 5, tree, &code_length_bitdepth[0]); - ConvertBitDepthsToSymbols(code_length_bitdepth, kCodeLengthCodes, - &code_length_bitdepth_symbols[0]); - - // Now, we have all the data, let's start storing it - StoreHuffmanTreeOfHuffmanTreeToBitMask(num_codes, code_length_bitdepth, - storage_ix, storage); - - if (num_codes == 1) { - code_length_bitdepth[code] = 0; - } - - // Store the real huffman tree now. - StoreHuffmanTreeToBitMask(huffman_tree_size, - huffman_tree, - huffman_tree_extra_bits, - &code_length_bitdepth[0], - code_length_bitdepth_symbols, - storage_ix, storage); -} - -void BuildAndStoreHuffmanTree(const uint32_t *histogram, - const size_t length, - HuffmanTree* tree, - uint8_t* depth, - uint16_t* bits, - size_t* storage_ix, - uint8_t* storage) { - size_t count = 0; - size_t s4[4] = { 0 }; - for (size_t i = 0; i < length; i++) { - if (histogram[i]) { - if (count < 4) { - s4[count] = i; - } else if (count > 4) { - break; - } - count++; - } - } - - size_t max_bits_counter = length - 1; - size_t max_bits = 0; - while (max_bits_counter) { - max_bits_counter >>= 1; - ++max_bits; - } - - if (count <= 1) { - WriteBits(4, 1, storage_ix, storage); - WriteBits(max_bits, s4[0], storage_ix, storage); - return; - } - - CreateHuffmanTree(histogram, length, 15, tree, depth); - ConvertBitDepthsToSymbols(depth, length, bits); - - if (count <= 4) { - StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage); - } else { - StoreHuffmanTree(depth, length, tree, storage_ix, storage); - } -} - -static inline bool SortHuffmanTree(const HuffmanTree& v0, - const HuffmanTree& v1) { - return v0.total_count_ < v1.total_count_; -} - -void BuildAndStoreHuffmanTreeFast(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) { - WriteBits(4, 1, storage_ix, storage); - WriteBits(max_bits, symbols[0], storage_ix, storage); - return; - } - - const size_t max_tree_size = 2 * length + 1; - HuffmanTree* const tree = - static_cast<HuffmanTree*>(malloc(max_tree_size * sizeof(HuffmanTree))); - for (uint32_t count_limit = 1; ; count_limit *= 2) { - HuffmanTree* node = tree; - for (size_t i = length; i != 0;) { - --i; - if (histogram[i]) { - if (PREDICT_TRUE(histogram[i] >= count_limit)) { - *node = HuffmanTree(histogram[i], -1, static_cast<int16_t>(i)); - } else { - *node = HuffmanTree(count_limit, -1, static_cast<int16_t>(i)); - } - ++node; - } - } - const int n = static_cast<int>(node - tree); - std::sort(tree, node, 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. - const HuffmanTree sentinel(std::numeric_limits<int>::max(), -1, -1); - *node++ = sentinel; - *node++ = sentinel; - - int i = 0; // Points to the next leaf node. - int j = n + 1; // Points to the next non-leaf node. - for (int 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_ = static_cast<int16_t>(left); - node[-1].index_right_or_value_ = static_cast<int16_t>(right); - // Add back the last sentinel node. - *node++ = sentinel; - } - SetDepth(tree[2 * n - 1], &tree[0], depth, 0); - // We need to pack the Huffman tree in 14 bits. - // If this was not successful, add fake entities to the lowest values - // and retry. - if (PREDICT_TRUE(*std::max_element(&depth[0], &depth[length]) <= 14)) { - break; - } - } - free(tree); - ConvertBitDepthsToSymbols(depth, length, bits); - if (count <= 4) { - // value of 1 indicates a simple Huffman code - WriteBits(2, 1, storage_ix, storage); - WriteBits(2, count - 1, storage_ix, storage); // NSYM - 1 - - // Sort - for (size_t i = 0; i < count; i++) { - for (size_t j = i + 1; j < count; j++) { - if (depth[symbols[j]] < depth[symbols[i]]) { - std::swap(symbols[j], symbols[i]); - } - } - } - - if (count == 2) { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - } else if (count == 3) { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - WriteBits(max_bits, symbols[2], storage_ix, storage); - } else { - WriteBits(max_bits, symbols[0], storage_ix, storage); - WriteBits(max_bits, symbols[1], storage_ix, storage); - WriteBits(max_bits, symbols[2], storage_ix, storage); - WriteBits(max_bits, symbols[3], storage_ix, storage); - // tree-select - WriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage); - } - } else { - // Complex Huffman Tree - StoreStaticCodeLengthCode(storage_ix, storage); - - // Actual rle coding. - uint8_t previous_value = 8; - for (size_t i = 0; i < length;) { - const uint8_t value = depth[i]; - size_t reps = 1; - for (size_t k = i + 1; k < length && depth[k] == value; ++k) { - ++reps; - } - i += reps; - if (value == 0) { - WriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps], - storage_ix, storage); - } else { - if (previous_value != value) { - WriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], - storage_ix, storage); - --reps; - } - if (reps < 3) { - while (reps != 0) { - reps--; - WriteBits(kCodeLengthDepth[value], kCodeLengthBits[value], - storage_ix, storage); - } - } else { - reps -= 3; - WriteBits(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]; - for (size_t i = index; i != 0; --i) { - v[i] = v[i - 1]; - } - v[0] = value; -} - -static void MoveToFrontTransform(const uint32_t* __restrict v_in, - const size_t v_size, - uint32_t* v_out) { - if (v_size == 0) { - return; - } - uint32_t max_value = *std::max_element(v_in, v_in + v_size); - assert(max_value < 256u); - uint8_t mtf[256]; - size_t mtf_size = max_value + 1; - for (uint32_t i = 0; i <= max_value; ++i) { - mtf[i] = static_cast<uint8_t>(i); - } - for (size_t i = 0; i < v_size; ++i) { - size_t index = IndexOf(mtf, mtf_size, static_cast<uint8_t>(v_in[i])); - assert(index < mtf_size); - v_out[i] = static_cast<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* __restrict v, - size_t* __restrict out_size, - uint32_t* __restrict max_run_length_prefix) { - uint32_t max_reps = 0; - for (size_t i = 0; i < in_size;) { - for (; i < in_size && v[i] != 0; ++i) ; - uint32_t reps = 0; - for (; i < in_size && v[i] == 0; ++i) { - ++reps; - } - max_reps = std::max(reps, max_reps); - } - uint32_t max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0; - max_prefix = std::min(max_prefix, *max_run_length_prefix); - *max_run_length_prefix = max_prefix; - *out_size = 0; - for (size_t i = 0; i < in_size;) { - assert(*out_size <= i); - if (v[i] != 0) { - v[*out_size] = v[i] + *max_run_length_prefix; - ++i; - ++(*out_size); - } else { - uint32_t reps = 1; - for (size_t 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); - } - } - } - } -} - -void EncodeContextMap(const std::vector<uint32_t>& context_map, - size_t num_clusters, - HuffmanTree* tree, - size_t* storage_ix, uint8_t* storage) { - StoreVarLenUint8(num_clusters - 1, storage_ix, storage); - - if (num_clusters == 1) { - return; - } - - uint32_t* rle_symbols = new uint32_t[context_map.size()]; - MoveToFrontTransform(&context_map[0], context_map.size(), rle_symbols); - uint32_t max_run_length_prefix = 6; - size_t num_rle_symbols = 0; - RunLengthCodeZeros(context_map.size(), rle_symbols, - &num_rle_symbols, &max_run_length_prefix); - uint32_t histogram[kContextMapAlphabetSize]; - memset(histogram, 0, sizeof(histogram)); - static const int kSymbolBits = 9; - static const uint32_t kSymbolMask = (1u << kSymbolBits) - 1u; - for (size_t i = 0; i < num_rle_symbols; ++i) { - ++histogram[rle_symbols[i] & kSymbolMask]; - } - bool use_rle = max_run_length_prefix > 0; - WriteBits(1, use_rle, storage_ix, storage); - if (use_rle) { - WriteBits(4, max_run_length_prefix - 1, storage_ix, storage); - } - uint8_t depths[kContextMapAlphabetSize]; - uint16_t bits[kContextMapAlphabetSize]; - memset(depths, 0, sizeof(depths)); - memset(bits, 0, sizeof(bits)); - BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix, - tree, depths, bits, storage_ix, storage); - for (size_t 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] >> kSymbolBits; - WriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage); - if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) { - WriteBits(rle_symbol, extra_bits_val, storage_ix, storage); - } - } - WriteBits(1, 1, storage_ix, storage); // use move-to-front - delete[] rle_symbols; -} - -void StoreBlockSwitch(const BlockSplitCode& code, - const size_t block_ix, - size_t* storage_ix, - uint8_t* storage) { - if (block_ix > 0) { - size_t typecode = code.type_code[block_ix]; - WriteBits(code.type_depths[typecode], code.type_bits[typecode], - storage_ix, storage); - } - size_t lencode = code.length_prefix[block_ix]; - WriteBits(code.length_depths[lencode], code.length_bits[lencode], - storage_ix, storage); - WriteBits(code.length_nextra[block_ix], code.length_extra[block_ix], - storage_ix, storage); -} - -static void BuildAndStoreBlockSplitCode(const std::vector<uint8_t>& types, - const std::vector<uint32_t>& lengths, - const size_t num_types, - HuffmanTree* tree, - BlockSplitCode* code, - size_t* storage_ix, - uint8_t* storage) { - const size_t num_blocks = types.size(); - uint32_t type_histo[kBlockTypeAlphabetSize]; - uint32_t length_histo[kNumBlockLenPrefixes]; - memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0])); - memset(length_histo, 0, sizeof(length_histo)); - size_t last_type = 1; - size_t second_last_type = 0; - code->type_code.resize(num_blocks); - code->length_prefix.resize(num_blocks); - code->length_nextra.resize(num_blocks); - code->length_extra.resize(num_blocks); - code->type_depths.resize(num_types + 2); - code->type_bits.resize(num_types + 2); - memset(code->length_depths, 0, sizeof(code->length_depths)); - memset(code->length_bits, 0, sizeof(code->length_bits)); - for (size_t i = 0; i < num_blocks; ++i) { - size_t type = types[i]; - size_t type_code = (type == last_type + 1 ? 1 : - type == second_last_type ? 0 : - type + 2); - second_last_type = last_type; - last_type = type; - code->type_code[i] = static_cast<uint32_t>(type_code); - if (i != 0) ++type_histo[type_code]; - GetBlockLengthPrefixCode(lengths[i], - &code->length_prefix[i], - &code->length_nextra[i], - &code->length_extra[i]); - ++length_histo[code->length_prefix[i]]; - } - StoreVarLenUint8(num_types - 1, storage_ix, storage); - if (num_types > 1) { - BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, tree, - &code->type_depths[0], &code->type_bits[0], - storage_ix, storage); - BuildAndStoreHuffmanTree(&length_histo[0], kNumBlockLenPrefixes, tree, - &code->length_depths[0], &code->length_bits[0], - storage_ix, storage); - StoreBlockSwitch(*code, 0, storage_ix, storage); - } -} - -void StoreTrivialContextMap(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 histogram[kContextMapAlphabetSize]; - uint8_t depths[kContextMapAlphabetSize]; - uint16_t bits[kContextMapAlphabetSize]; - memset(histogram, 0, alphabet_size * sizeof(histogram[0])); - memset(depths, 0, alphabet_size * sizeof(depths[0])); - memset(bits, 0, alphabet_size * sizeof(bits[0])); - // Write RLEMAX. - WriteBits(1, 1, storage_ix, storage); - WriteBits(4, repeat_code - 1, storage_ix, storage); - histogram[repeat_code] = static_cast<uint32_t>(num_types); - histogram[0] = 1; - for (size_t i = context_bits; i < alphabet_size; ++i) { - histogram[i] = 1; - } - BuildAndStoreHuffmanTree(&histogram[0], alphabet_size, tree, - &depths[0], &bits[0], - storage_ix, storage); - for (size_t i = 0; i < num_types; ++i) { - size_t code = (i == 0 ? 0 : i + context_bits - 1); - WriteBits(depths[code], bits[code], storage_ix, storage); - WriteBits(depths[repeat_code], bits[repeat_code], storage_ix, storage); - WriteBits(repeat_code, repeat_bits, storage_ix, storage); - } - // Write IMTF (inverse-move-to-front) bit. - WriteBits(1, 1, storage_ix, storage); - } -} - -// Manages the encoding of one block category (literal, command or distance). -class BlockEncoder { - public: - BlockEncoder(size_t alphabet_size, - size_t num_block_types, - const std::vector<uint8_t>& block_types, - const std::vector<uint32_t>& block_lengths) - : alphabet_size_(alphabet_size), - num_block_types_(num_block_types), - block_types_(block_types), - block_lengths_(block_lengths), - block_ix_(0), - block_len_(block_lengths.empty() ? 0 : block_lengths[0]), - entropy_ix_(0) {} - - // Creates entropy codes of block lengths and block types and stores them - // to the bit stream. - void BuildAndStoreBlockSwitchEntropyCodes(HuffmanTree* tree, - size_t* storage_ix, - uint8_t* storage) { - BuildAndStoreBlockSplitCode( - block_types_, block_lengths_, num_block_types_, - tree, &block_split_code_, storage_ix, storage); - } - - // Creates entropy codes for all block types and stores them to the bit - // stream. - template<int kSize> - void BuildAndStoreEntropyCodes( - const std::vector<Histogram<kSize> >& histograms, - HuffmanTree* tree, - size_t* storage_ix, uint8_t* storage) { - depths_.resize(histograms.size() * alphabet_size_); - bits_.resize(histograms.size() * alphabet_size_); - for (size_t i = 0; i < histograms.size(); ++i) { - size_t ix = i * alphabet_size_; - BuildAndStoreHuffmanTree(&histograms[i].data_[0], alphabet_size_, - tree, - &depths_[ix], &bits_[ix], - 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. - void StoreSymbol(size_t symbol, size_t* storage_ix, uint8_t* storage) { - if (block_len_ == 0) { - ++block_ix_; - block_len_ = block_lengths_[block_ix_]; - entropy_ix_ = block_types_[block_ix_] * alphabet_size_; - StoreBlockSwitch(block_split_code_, block_ix_, storage_ix, storage); - } - --block_len_; - size_t ix = entropy_ix_ + symbol; - WriteBits(depths_[ix], 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. - template<int kContextBits> - void StoreSymbolWithContext(size_t symbol, size_t context, - const std::vector<uint32_t>& context_map, - size_t* storage_ix, uint8_t* storage) { - if (block_len_ == 0) { - ++block_ix_; - block_len_ = block_lengths_[block_ix_]; - size_t block_type = block_types_[block_ix_]; - entropy_ix_ = block_type << kContextBits; - StoreBlockSwitch(block_split_code_, block_ix_, storage_ix, storage); - } - --block_len_; - size_t histo_ix = context_map[entropy_ix_ + context]; - size_t ix = histo_ix * alphabet_size_ + symbol; - WriteBits(depths_[ix], bits_[ix], storage_ix, storage); - } - - private: - const size_t alphabet_size_; - const size_t num_block_types_; - const std::vector<uint8_t>& block_types_; - const std::vector<uint32_t>& block_lengths_; - BlockSplitCode block_split_code_; - size_t block_ix_; - size_t block_len_; - size_t entropy_ix_; - std::vector<uint8_t> depths_; - std::vector<uint16_t> bits_; -}; - -static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) { - *storage_ix = (*storage_ix + 7u) & ~7u; - storage[*storage_ix >> 3] = 0; -} - -void StoreMetaBlock(const uint8_t* input, - size_t start_pos, - size_t length, - size_t mask, - uint8_t prev_byte, - uint8_t prev_byte2, - bool is_last, - uint32_t num_direct_distance_codes, - uint32_t distance_postfix_bits, - ContextType literal_context_mode, - const brotli::Command *commands, - size_t n_commands, - const MetaBlockSplit& mb, - size_t *storage_ix, - uint8_t *storage) { - StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); - - size_t num_distance_codes = - kNumDistanceShortCodes + num_direct_distance_codes + - (48u << distance_postfix_bits); - - HuffmanTree* tree = static_cast<HuffmanTree*>( - malloc(kMaxHuffmanTreeSize * sizeof(HuffmanTree))); - BlockEncoder literal_enc(256, - mb.literal_split.num_types, - mb.literal_split.types, - mb.literal_split.lengths); - BlockEncoder command_enc(kNumCommandPrefixes, - mb.command_split.num_types, - mb.command_split.types, - mb.command_split.lengths); - BlockEncoder distance_enc(num_distance_codes, - mb.distance_split.num_types, - mb.distance_split.types, - mb.distance_split.lengths); - - literal_enc.BuildAndStoreBlockSwitchEntropyCodes(tree, storage_ix, storage); - command_enc.BuildAndStoreBlockSwitchEntropyCodes(tree, storage_ix, storage); - distance_enc.BuildAndStoreBlockSwitchEntropyCodes(tree, storage_ix, storage); - - WriteBits(2, distance_postfix_bits, storage_ix, storage); - WriteBits(4, num_direct_distance_codes >> distance_postfix_bits, - storage_ix, storage); - for (size_t i = 0; i < mb.literal_split.num_types; ++i) { - WriteBits(2, literal_context_mode, storage_ix, storage); - } - - size_t num_literal_histograms = mb.literal_histograms.size(); - if (mb.literal_context_map.empty()) { - StoreTrivialContextMap(num_literal_histograms, kLiteralContextBits, tree, - storage_ix, storage); - } else { - EncodeContextMap(mb.literal_context_map, num_literal_histograms, tree, - storage_ix, storage); - } - - size_t num_dist_histograms = mb.distance_histograms.size(); - if (mb.distance_context_map.empty()) { - StoreTrivialContextMap(num_dist_histograms, kDistanceContextBits, tree, - storage_ix, storage); - } else { - EncodeContextMap(mb.distance_context_map, num_dist_histograms, tree, - storage_ix, storage); - } - - literal_enc.BuildAndStoreEntropyCodes(mb.literal_histograms, tree, - storage_ix, storage); - command_enc.BuildAndStoreEntropyCodes(mb.command_histograms, tree, - storage_ix, storage); - distance_enc.BuildAndStoreEntropyCodes(mb.distance_histograms, tree, - storage_ix, storage); - free(tree); - - size_t pos = start_pos; - for (size_t i = 0; i < n_commands; ++i) { - const Command cmd = commands[i]; - size_t cmd_code = cmd.cmd_prefix_; - command_enc.StoreSymbol(cmd_code, storage_ix, storage); - StoreCommandExtra(cmd, storage_ix, storage); - if (mb.literal_context_map.empty()) { - for (size_t j = cmd.insert_len_; j != 0; --j) { - literal_enc.StoreSymbol(input[pos & mask], storage_ix, storage); - ++pos; - } - } else { - for (size_t j = cmd.insert_len_; j != 0; --j) { - size_t context = Context(prev_byte, prev_byte2, literal_context_mode); - uint8_t literal = input[pos & mask]; - literal_enc.StoreSymbolWithContext<kLiteralContextBits>( - literal, context, mb.literal_context_map, storage_ix, storage); - prev_byte2 = prev_byte; - prev_byte = literal; - ++pos; - } - } - pos += cmd.copy_len(); - if (cmd.copy_len()) { - prev_byte2 = input[(pos - 2) & mask]; - prev_byte = input[(pos - 1) & mask]; - if (cmd.cmd_prefix_ >= 128) { - size_t dist_code = cmd.dist_prefix_; - uint32_t distnumextra = cmd.dist_extra_ >> 24; - uint64_t distextra = cmd.dist_extra_ & 0xffffff; - if (mb.distance_context_map.empty()) { - distance_enc.StoreSymbol(dist_code, storage_ix, storage); - } else { - size_t context = cmd.DistanceContext(); - distance_enc.StoreSymbolWithContext<kDistanceContextBits>( - dist_code, context, mb.distance_context_map, storage_ix, storage); - } - brotli::WriteBits(distnumextra, distextra, storage_ix, storage); - } - } - } - if (is_last) { - JumpToByteBoundary(storage_ix, storage); - } -} - -static void BuildHistograms(const uint8_t* input, - size_t start_pos, - size_t mask, - const brotli::Command *commands, - size_t n_commands, - HistogramLiteral* lit_histo, - HistogramCommand* cmd_histo, - HistogramDistance* dist_histo) { - size_t pos = start_pos; - for (size_t i = 0; i < n_commands; ++i) { - const Command cmd = commands[i]; - cmd_histo->Add(cmd.cmd_prefix_); - for (size_t j = cmd.insert_len_; j != 0; --j) { - lit_histo->Add(input[pos & mask]); - ++pos; - } - pos += cmd.copy_len(); - if (cmd.copy_len() && cmd.cmd_prefix_ >= 128) { - dist_histo->Add(cmd.dist_prefix_); - } - } -} - -static void StoreDataWithHuffmanCodes(const uint8_t* input, - size_t start_pos, - size_t mask, - const brotli::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; - for (size_t i = 0; i < n_commands; ++i) { - const Command cmd = commands[i]; - const size_t cmd_code = cmd.cmd_prefix_; - WriteBits(cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage); - StoreCommandExtra(cmd, storage_ix, storage); - for (size_t j = cmd.insert_len_; j != 0; --j) { - const uint8_t literal = input[pos & mask]; - WriteBits(lit_depth[literal], lit_bits[literal], storage_ix, storage); - ++pos; - } - pos += cmd.copy_len(); - if (cmd.copy_len() && cmd.cmd_prefix_ >= 128) { - const size_t dist_code = cmd.dist_prefix_; - const uint32_t distnumextra = cmd.dist_extra_ >> 24; - const uint32_t distextra = cmd.dist_extra_ & 0xffffff; - WriteBits(dist_depth[dist_code], dist_bits[dist_code], - storage_ix, storage); - WriteBits(distnumextra, distextra, storage_ix, storage); - } - } -} - -void StoreMetaBlockTrivial(const uint8_t* input, - size_t start_pos, - size_t length, - size_t mask, - bool is_last, - const brotli::Command *commands, - size_t n_commands, - size_t *storage_ix, - uint8_t *storage) { - StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); - - HistogramLiteral lit_histo; - HistogramCommand cmd_histo; - HistogramDistance dist_histo; - - BuildHistograms(input, start_pos, mask, commands, n_commands, - &lit_histo, &cmd_histo, &dist_histo); - - WriteBits(13, 0, storage_ix, storage); - - std::vector<uint8_t> lit_depth(256); - std::vector<uint16_t> lit_bits(256); - std::vector<uint8_t> cmd_depth(kNumCommandPrefixes); - std::vector<uint16_t> cmd_bits(kNumCommandPrefixes); - std::vector<uint8_t> dist_depth(64); - std::vector<uint16_t> dist_bits(64); - - HuffmanTree* tree = static_cast<HuffmanTree*>( - malloc(kMaxHuffmanTreeSize * sizeof(HuffmanTree))); - BuildAndStoreHuffmanTree(&lit_histo.data_[0], 256, tree, - &lit_depth[0], &lit_bits[0], - storage_ix, storage); - BuildAndStoreHuffmanTree(&cmd_histo.data_[0], kNumCommandPrefixes, tree, - &cmd_depth[0], &cmd_bits[0], - storage_ix, storage); - BuildAndStoreHuffmanTree(&dist_histo.data_[0], 64, tree, - &dist_depth[0], &dist_bits[0], - storage_ix, storage); - free(tree); - StoreDataWithHuffmanCodes(input, start_pos, mask, commands, - n_commands, &lit_depth[0], &lit_bits[0], - &cmd_depth[0], &cmd_bits[0], - &dist_depth[0], &dist_bits[0], - storage_ix, storage); - if (is_last) { - JumpToByteBoundary(storage_ix, storage); - } -} - -void StoreMetaBlockFast(const uint8_t* input, - size_t start_pos, - size_t length, - size_t mask, - bool is_last, - const brotli::Command *commands, - size_t n_commands, - size_t *storage_ix, - uint8_t *storage) { - StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage); - - WriteBits(13, 0, storage_ix, storage); - - if (n_commands <= 128) { - uint32_t histogram[256] = { 0 }; - size_t pos = start_pos; - size_t num_literals = 0; - for (size_t i = 0; i < n_commands; ++i) { - const Command cmd = commands[i]; - for (size_t j = cmd.insert_len_; j != 0; --j) { - ++histogram[input[pos & mask]]; - ++pos; - } - num_literals += cmd.insert_len_; - pos += cmd.copy_len(); - } - uint8_t lit_depth[256] = { 0 }; - uint16_t lit_bits[256] = { 0 }; - BuildAndStoreHuffmanTreeFast(histogram, num_literals, - /* max_bits = */ 8, - lit_depth, lit_bits, - storage_ix, storage); - StoreStaticCommandHuffmanTree(storage_ix, storage); - StoreStaticDistanceHuffmanTree(storage_ix, storage); - StoreDataWithHuffmanCodes(input, start_pos, mask, commands, - n_commands, &lit_depth[0], &lit_bits[0], - kStaticCommandCodeDepth, - kStaticCommandCodeBits, - kStaticDistanceCodeDepth, - kStaticDistanceCodeBits, - storage_ix, storage); - } else { - HistogramLiteral lit_histo; - HistogramCommand cmd_histo; - HistogramDistance dist_histo; - BuildHistograms(input, start_pos, mask, commands, n_commands, - &lit_histo, &cmd_histo, &dist_histo); - std::vector<uint8_t> lit_depth(256); - std::vector<uint16_t> lit_bits(256); - std::vector<uint8_t> cmd_depth(kNumCommandPrefixes); - std::vector<uint16_t> cmd_bits(kNumCommandPrefixes); - std::vector<uint8_t> dist_depth(64); - std::vector<uint16_t> dist_bits(64); - BuildAndStoreHuffmanTreeFast(&lit_histo.data_[0], lit_histo.total_count_, - /* max_bits = */ 8, - &lit_depth[0], &lit_bits[0], - storage_ix, storage); - BuildAndStoreHuffmanTreeFast(&cmd_histo.data_[0], cmd_histo.total_count_, - /* max_bits = */ 10, - &cmd_depth[0], &cmd_bits[0], - storage_ix, storage); - BuildAndStoreHuffmanTreeFast(&dist_histo.data_[0], dist_histo.total_count_, - /* max_bits = */ 6, - &dist_depth[0], &dist_bits[0], - storage_ix, storage); - StoreDataWithHuffmanCodes(input, start_pos, mask, commands, - n_commands, &lit_depth[0], &lit_bits[0], - &cmd_depth[0], &cmd_bits[0], - &dist_depth[0], &dist_bits[0], - storage_ix, storage); - } - - if (is_last) { - JumpToByteBoundary(storage_ix, storage); - } -} - -// This is for storing uncompressed blocks (simple raw storage of -// bytes-as-bytes). -void StoreUncompressedMetaBlock(bool final_block, - const uint8_t * __restrict input, - size_t position, size_t mask, - size_t len, - size_t * __restrict storage_ix, - uint8_t * __restrict storage) { - StoreUncompressedMetaBlockHeader(len, storage_ix, storage); - JumpToByteBoundary(storage_ix, storage); - - size_t masked_pos = position & mask; - 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 WriteBits. - brotli::WriteBitsPrepareStorage(*storage_ix, storage); - - // Since the uncompressed block itself may not be the final block, add an - // empty one after this. - if (final_block) { - brotli::WriteBits(1, 1, storage_ix, storage); // islast - brotli::WriteBits(1, 1, storage_ix, storage); // isempty - JumpToByteBoundary(storage_ix, storage); - } -} - -void StoreSyncMetaBlock(size_t * __restrict storage_ix, - uint8_t * __restrict storage) { - // Empty metadata meta-block bit pattern: - // 1 bit: is_last (0) - // 2 bits: num nibbles (3) - // 1 bit: reserved (0) - // 2 bits: metadata length bytes (0) - WriteBits(6, 6, storage_ix, storage); - JumpToByteBoundary(storage_ix, storage); -} - -} // namespace brotli |