mirror of
https://github.com/google/brotli.git
synced 2024-11-22 11:40:06 +00:00
83aa24dc86
* Change order of members of bit reader state structure. * Remove unused includes for assert. Add BROTLI_DCHECK macros and use it instead of assert. * Do not calculate nbits in common case of ReadSymbol. * Introduce and use PREDICT_TRUE / PREDICT_FALSE macros. * Allocate less memory in the brotli decoder if it knows the result size beforehand. Before this, the decoder would always allocate 16MB if the encoder annotated the window size as 22 bit (which is the default), even if the file is only a few KB uncompressed. Now, it'll only allocate a ringbuffer as large as needed for the result file. But only if it can know the filesize, it's not possible to know that if there are multiple metablocks or too large uncompressed metablock.
60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/* Copyright 2013 Google Inc. All Rights Reserved.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
/* Utilities for building Huffman decoding tables. */
|
|
|
|
#ifndef BROTLI_DEC_HUFFMAN_H_
|
|
#define BROTLI_DEC_HUFFMAN_H_
|
|
|
|
#include "./types.h"
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
extern "C" {
|
|
#endif
|
|
|
|
/* Maximum possible Huffman table size for an alphabet size of 704, max code
|
|
* length 15 and root table bits 8. */
|
|
#define BROTLI_HUFFMAN_MAX_TABLE_SIZE 1080
|
|
|
|
typedef struct {
|
|
uint8_t bits; /* number of bits used for this symbol */
|
|
uint16_t value; /* symbol value or table offset */
|
|
} HuffmanCode;
|
|
|
|
/* Builds Huffman lookup table assuming code lengths are in symbol order. */
|
|
/* Returns false in case of error (invalid tree or memory error). */
|
|
int BrotliBuildHuffmanTable(HuffmanCode* root_table,
|
|
int root_bits,
|
|
const uint8_t* const code_lengths,
|
|
int code_lengths_size);
|
|
|
|
/* Contains a collection of huffman trees with the same alphabet size. */
|
|
typedef struct {
|
|
int alphabet_size;
|
|
int num_htrees;
|
|
HuffmanCode* codes;
|
|
HuffmanCode** htrees;
|
|
} HuffmanTreeGroup;
|
|
|
|
void BrotliHuffmanTreeGroupInit(HuffmanTreeGroup* group,
|
|
int alphabet_size, int ntrees);
|
|
void BrotliHuffmanTreeGroupRelease(HuffmanTreeGroup* group);
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
} /* extern "C" */
|
|
#endif
|
|
|
|
#endif /* BROTLI_DEC_HUFFMAN_H_ */
|