352a4f49ab
[and in turn a malloc]. Also, a few related const fixes. Change-Id: I229519b1c34d41c78d9ad2403f1e25feab3c9d93
55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
|
|
//
|
|
// This code is licensed under the same terms as WebM:
|
|
// Software License Agreement: http://www.webmproject.org/license/software/
|
|
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// Author: jyrki@google.com (Jyrki Alakuijala)
|
|
//
|
|
// Flate like entropy encoding (Huffman) for webp lossless
|
|
|
|
#ifndef WEBP_UTILS_HUFFMAN_ENCODE_H_
|
|
#define WEBP_UTILS_HUFFMAN_ENCODE_H_
|
|
|
|
#ifdef USE_LOSSLESS_ENCODER
|
|
|
|
#include <stdint.h>
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
extern "C" {
|
|
#endif
|
|
|
|
// 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
|
|
//
|
|
// Returns 0 when an error has occured.
|
|
int VP8LCreateHuffmanTree(const int* data, const int length,
|
|
const int tree_limit, uint8_t* depth);
|
|
|
|
// Write a huffman tree from bit depths. The generated Huffman tree is
|
|
// compressed once more using a Huffman tree.
|
|
void VP8LCreateCompressedHuffmanTree(const uint8_t* const depth, int len,
|
|
int* num_symbols,
|
|
uint8_t* tree,
|
|
uint8_t* extra_bits_data);
|
|
|
|
// Get the actual bit values for a tree of bit depths.
|
|
void VP8LConvertBitDepthsToSymbols(const uint8_t* depth, int len,
|
|
uint16_t* bits);
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
}
|
|
#endif
|
|
|
|
#endif
|
|
|
|
#endif // WEBP_UTILS_HUFFMAN_ENCODE_H_
|