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Diffstat (limited to 'third_party/jpeg-xl/lib/jpegli/huffman.cc')
| -rw-r--r-- | third_party/jpeg-xl/lib/jpegli/huffman.cc | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jpegli/huffman.cc b/third_party/jpeg-xl/lib/jpegli/huffman.cc new file mode 100644 index 0000000000..1cf88a5536 --- /dev/null +++ b/third_party/jpeg-xl/lib/jpegli/huffman.cc @@ -0,0 +1,321 @@ +// Copyright (c) the JPEG XL Project Authors. All rights reserved. +// +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#include "lib/jpegli/huffman.h" + +#include <limits> +#include <vector> + +#include "lib/jpegli/common.h" +#include "lib/jpegli/error.h" + +namespace jpegli { + +// Returns the table width of the next 2nd level table, count is the histogram +// of bit lengths for the remaining symbols, len is the code length of the next +// processed symbol. +static inline int NextTableBitSize(const int* count, int len) { + int left = 1 << (len - kJpegHuffmanRootTableBits); + while (len < static_cast<int>(kJpegHuffmanMaxBitLength)) { + left -= count[len]; + if (left <= 0) break; + ++len; + left <<= 1; + } + return len - kJpegHuffmanRootTableBits; +} + +void BuildJpegHuffmanTable(const uint32_t* count, const uint32_t* symbols, + HuffmanTableEntry* lut) { + HuffmanTableEntry code; // current table entry + HuffmanTableEntry* table; // next available space in table + int len; // current code length + int idx; // symbol index + int key; // prefix code + int reps; // number of replicate key values in current table + int low; // low bits for current root entry + int table_bits; // key length of current table + int table_size; // size of current table + + // Make a local copy of the input bit length histogram. + int tmp_count[kJpegHuffmanMaxBitLength + 1] = {0}; + int total_count = 0; + for (len = 1; len <= static_cast<int>(kJpegHuffmanMaxBitLength); ++len) { + tmp_count[len] = count[len]; + total_count += tmp_count[len]; + } + + table = lut; + table_bits = kJpegHuffmanRootTableBits; + table_size = 1 << table_bits; + + // Special case code with only one value. + if (total_count == 1) { + code.bits = 0; + code.value = symbols[0]; + for (key = 0; key < table_size; ++key) { + table[key] = code; + } + return; + } + + // Fill in root table. + key = 0; + idx = 0; + for (len = 1; len <= kJpegHuffmanRootTableBits; ++len) { + for (; tmp_count[len] > 0; --tmp_count[len]) { + code.bits = len; + code.value = symbols[idx++]; + reps = 1 << (kJpegHuffmanRootTableBits - len); + while (reps--) { + table[key++] = code; + } + } + } + + // Fill in 2nd level tables and add pointers to root table. + table += table_size; + table_size = 0; + low = 0; + for (len = kJpegHuffmanRootTableBits + 1; + len <= static_cast<int>(kJpegHuffmanMaxBitLength); ++len) { + for (; tmp_count[len] > 0; --tmp_count[len]) { + // Start a new sub-table if the previous one is full. + if (low >= table_size) { + table += table_size; + table_bits = NextTableBitSize(tmp_count, len); + table_size = 1 << table_bits; + low = 0; + lut[key].bits = table_bits + kJpegHuffmanRootTableBits; + lut[key].value = (table - lut) - key; + ++key; + } + code.bits = len - kJpegHuffmanRootTableBits; + code.value = symbols[idx++]; + reps = 1 << (table_bits - code.bits); + while (reps--) { + table[low++] = code; + } + } + } +} + +// A node of a Huffman tree. +struct HuffmanTree { + HuffmanTree(uint32_t count, int16_t left, int16_t right) + : total_count(count), index_left(left), index_right_or_value(right) {} + uint32_t total_count; + int16_t index_left; + int16_t index_right_or_value; +}; + +void SetDepth(const HuffmanTree& p, HuffmanTree* pool, uint8_t* depth, + uint8_t level) { + if (p.index_left >= 0) { + ++level; + SetDepth(pool[p.index_left], pool, depth, level); + SetDepth(pool[p.index_right_or_value], pool, depth, level); + } else { + depth[p.index_right_or_value] = level; + } +} + +// Sort the root nodes, least popular first. +static JXL_INLINE bool Compare(const HuffmanTree& v0, const HuffmanTree& v1) { + return v0.total_count < v1.total_count; +} + +// This function will create a Huffman tree. +// +// The catch here is that the tree cannot be arbitrarily deep. +// Brotli specifies a maximum depth of 15 bits for "code trees" +// and 7 bits for "code length code trees." +// +// count_limit is the value that is to be faked as the minimum value +// and this minimum value is raised until the tree matches the +// maximum length requirement. +// +// This algorithm is not of excellent performance for very long data blocks, +// especially when population counts are longer than 2**tree_limit, but +// we are not planning to use this with extremely long blocks. +// +// See http://en.wikipedia.org/wiki/Huffman_coding +void CreateHuffmanTree(const uint32_t* data, const size_t length, + const int tree_limit, uint8_t* depth) { + // For block sizes below 64 kB, we never need to do a second iteration + // of this loop. Probably all of our block sizes will be smaller than + // that, so this loop is mostly of academic interest. If we actually + // would need this, we would be better off with the Katajainen algorithm. + for (uint32_t count_limit = 1;; count_limit *= 2) { + std::vector<HuffmanTree> tree; + tree.reserve(2 * length + 1); + + for (size_t i = length; i != 0;) { + --i; + if (data[i]) { + const uint32_t count = std::max(data[i], count_limit - 1); + tree.emplace_back(count, -1, static_cast<int16_t>(i)); + } + } + + const size_t n = tree.size(); + if (n == 1) { + // Fake value; will be fixed on upper level. + depth[tree[0].index_right_or_value] = 1; + break; + } + + std::stable_sort(tree.begin(), tree.end(), Compare); + + // 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<uint32_t>::max(), -1, -1); + tree.push_back(sentinel); + tree.push_back(sentinel); + + size_t i = 0; // Points to the next leaf node. + size_t j = n + 1; // Points to the next non-leaf node. + for (size_t k = n - 1; k != 0; --k) { + size_t 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. + size_t j_end = tree.size() - 1; + tree[j_end].total_count = + tree[left].total_count + tree[right].total_count; + tree[j_end].index_left = static_cast<int16_t>(left); + tree[j_end].index_right_or_value = static_cast<int16_t>(right); + + // Add back the last sentinel node. + tree.push_back(sentinel); + } + JXL_DASSERT(tree.size() == 2 * n + 1); + SetDepth(tree[2 * n - 1], &tree[0], depth, 0); + + // We need to pack the Huffman tree in tree_limit bits. + // If this was not successful, add fake entities to the lowest values + // and retry. + if (*std::max_element(&depth[0], &depth[length]) <= tree_limit) { + break; + } + } +} + +void ValidateHuffmanTable(j_common_ptr cinfo, const JHUFF_TBL* table, + bool is_dc) { + size_t total_symbols = 0; + size_t total_p = 0; + size_t max_depth = 0; + for (size_t d = 1; d <= kJpegHuffmanMaxBitLength; ++d) { + uint8_t count = table->bits[d]; + if (count) { + total_symbols += count; + total_p += (1u << (kJpegHuffmanMaxBitLength - d)) * count; + max_depth = d; + } + } + total_p += 1u << (kJpegHuffmanMaxBitLength - max_depth); // sentinel symbol + if (total_symbols == 0) { + JPEGLI_ERROR("Empty Huffman table"); + } + if (total_symbols > kJpegHuffmanAlphabetSize) { + JPEGLI_ERROR("Too many symbols in Huffman table"); + } + if (total_p != (1u << kJpegHuffmanMaxBitLength)) { + JPEGLI_ERROR("Invalid bit length distribution"); + } + uint8_t symbol_seen[kJpegHuffmanAlphabetSize] = {}; + for (size_t i = 0; i < total_symbols; ++i) { + uint8_t symbol = table->huffval[i]; + if (symbol_seen[symbol]) { + JPEGLI_ERROR("Duplicate symbol %d in Huffman table", symbol); + } + symbol_seen[symbol] = 1; + } +} + +void AddStandardHuffmanTables(j_common_ptr cinfo, bool is_dc) { + // Huffman tables from the JPEG standard. + static constexpr JHUFF_TBL kStandardDCTables[2] = { + // DC luma + {{0, 0, 1, 5, 1, 1, 1, 1, 1, 1}, + {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}, + FALSE}, + // DC chroma + {{0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1}, + {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}, + FALSE}}; + static constexpr JHUFF_TBL kStandardACTables[2] = { + // AC luma + {{0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 125}, + {0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06, + 0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08, + 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0, 0x24, 0x33, 0x62, 0x72, + 0x82, 0x09, 0x0a, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28, + 0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, + 0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, + 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74, 0x75, + 0x76, 0x77, 0x78, 0x79, 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, + 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, + 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, + 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, + 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2, + 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf1, 0xf2, 0xf3, 0xf4, + 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa}, + FALSE}, + // AC chroma + {{0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 119}, + {0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41, + 0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91, + 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0, 0x15, 0x62, 0x72, 0xd1, + 0x0a, 0x16, 0x24, 0x34, 0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26, + 0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, + 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, + 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74, + 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, + 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, + 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, + 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, + 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, + 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf2, 0xf3, 0xf4, + 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa}, + FALSE}}; + const JHUFF_TBL* std_tables = is_dc ? kStandardDCTables : kStandardACTables; + JHUFF_TBL** tables; + if (cinfo->is_decompressor) { + j_decompress_ptr cinfo_d = reinterpret_cast<j_decompress_ptr>(cinfo); + tables = is_dc ? cinfo_d->dc_huff_tbl_ptrs : cinfo_d->ac_huff_tbl_ptrs; + } else { + j_compress_ptr cinfo_c = reinterpret_cast<j_compress_ptr>(cinfo); + tables = is_dc ? cinfo_c->dc_huff_tbl_ptrs : cinfo_c->ac_huff_tbl_ptrs; + } + for (int i = 0; i < 2; ++i) { + if (tables[i] == nullptr) { + tables[i] = jpegli_alloc_huff_table(cinfo); + memcpy(tables[i], &std_tables[i], sizeof(JHUFF_TBL)); + ValidateHuffmanTable(cinfo, tables[i], is_dc); + } + } +} + +} // namespace jpegli |