mirror of
https://github.com/NekoX-Dev/NekoX.git
synced 2024-12-14 07:40:36 +01:00
62 lines
2.1 KiB
C
62 lines
2.1 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
|
|
//
|
|
// Use of this source code is governed by a BSD-style license
|
|
// that can be found in the COPYING file in the root of the source
|
|
// tree. An additional intellectual property rights grant can be found
|
|
// in the file PATENTS. All contributing project authors may
|
|
// be found in the AUTHORS file in the root of the source tree.
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// Author: Jyrki Alakuijala (jyrki@google.com)
|
|
//
|
|
// Entropy encoding (Huffman) for webp lossless
|
|
|
|
#ifndef WEBP_UTILS_HUFFMAN_ENCODE_H_
|
|
#define WEBP_UTILS_HUFFMAN_ENCODE_H_
|
|
|
|
#include "../webp/types.h"
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
// Struct for holding the tree header in coded form.
|
|
typedef struct {
|
|
uint8_t code; // value (0..15) or escape code (16,17,18)
|
|
uint8_t extra_bits; // extra bits for escape codes
|
|
} HuffmanTreeToken;
|
|
|
|
// Struct to represent the tree codes (depth and bits array).
|
|
typedef struct {
|
|
int num_symbols; // Number of symbols.
|
|
uint8_t* code_lengths; // Code lengths of the symbols.
|
|
uint16_t* codes; // Symbol Codes.
|
|
} HuffmanTreeCode;
|
|
|
|
// Struct to represent the Huffman tree.
|
|
// TODO(vikasa): Add comment for the fields of the Struct.
|
|
typedef struct {
|
|
uint32_t total_count_;
|
|
int value_;
|
|
int pool_index_left_; // Index for the left sub-tree.
|
|
int pool_index_right_; // Index for the right sub-tree.
|
|
} HuffmanTree;
|
|
|
|
// Turn the Huffman tree into a token sequence.
|
|
// Returns the number of tokens used.
|
|
int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
|
|
HuffmanTreeToken* tokens, int max_tokens);
|
|
|
|
// Create an optimized tree, and tokenize it.
|
|
// 'buf_rle' and 'huff_tree' are pre-allocated and the 'tree' is the constructed
|
|
// huffman code tree.
|
|
void VP8LCreateHuffmanTree(uint32_t* const histogram, int tree_depth_limit,
|
|
uint8_t* const buf_rle, HuffmanTree* const huff_tree,
|
|
HuffmanTreeCode* const tree);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif // WEBP_UTILS_HUFFMAN_ENCODE_H_
|