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Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/enc_huffman_tree.h')
-rw-r--r-- | third_party/jpeg-xl/lib/jxl/enc_huffman_tree.h | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/enc_huffman_tree.h b/third_party/jpeg-xl/lib/jxl/enc_huffman_tree.h new file mode 100644 index 0000000000..7d716cd3b5 --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/enc_huffman_tree.h @@ -0,0 +1,52 @@ +// 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. + +// Library for creating Huffman codes from population counts. + +#ifndef LIB_JXL_HUFFMAN_TREE_H_ +#define LIB_JXL_HUFFMAN_TREE_H_ + +#include <stdint.h> +#include <stdlib.h> + +namespace jxl { + +// 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); + +// This function will create a Huffman tree. +// +// The (data,length) contains the population counts. +// The tree_limit is the maximum bit depth of the Huffman codes. +// +// The depth contains the tree, i.e., how many bits are used for +// the symbol. +// +// See http://en.wikipedia.org/wiki/Huffman_coding +void CreateHuffmanTree(const uint32_t* data, size_t length, int tree_limit, + uint8_t* depth); + +// Write a Huffman tree from bit depths into the bitstream representation +// of a Huffman tree. The generated Huffman tree is to be compressed once +// more using a Huffman tree +void WriteHuffmanTree(const uint8_t* depth, size_t length, size_t* tree_size, + uint8_t* tree, uint8_t* extra_bits_data); + +// Get the actual bit values for a tree of bit depths. +void ConvertBitDepthsToSymbols(const uint8_t* depth, size_t len, + uint16_t* bits); + +} // namespace jxl + +#endif // LIB_JXL_HUFFMAN_TREE_H_ |