libwebp-0.6.0-rc1

third_party/libwebp/utils/huffman_encode.h

-// 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.
-typedef struct {
-  uint32_t total_count_;   // Symbol frequency.
-  int value_;              // Symbol 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_