63 lines
1.7 KiB
C++
63 lines
1.7 KiB
C++
/* Copyright 2018 Dirk Steinke
|
|
|
|
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. */
|
|
|
|
#ifndef HUFFMAN_DECODER_H
|
|
#define HUFFMAN_DECODER_H
|
|
|
|
#include <vector>
|
|
#include "bitstream.h"
|
|
|
|
// Huffman decoder
|
|
class HuffmanDecoder {
|
|
public:
|
|
HuffmanDecoder(const unsigned char* symbolBitLengths,
|
|
const size_t symbolCount,
|
|
const bool disableZeroBitSymbols,
|
|
const unsigned char maxBitsPerTable);
|
|
|
|
bool error() const {
|
|
return _error;
|
|
}
|
|
|
|
size_t decode(BitInputStream& bis) const {
|
|
size_t v = bis.peek(_table0.peekBits);
|
|
signed short w = _table0.lookup[v];
|
|
if (w >= 0) {
|
|
bis.skip(w & 0xf);
|
|
return w >> 4;
|
|
}
|
|
return _decodeDeeper(bis, ~w);
|
|
}
|
|
|
|
private:
|
|
size_t _decodeDeeper(BitInputStream& bis, const size_t tableId) const;
|
|
bool _constructTables(const unsigned char* symbolBitLengths,
|
|
const size_t symbolCount,
|
|
const bool disableZeroBitSymbols,
|
|
const unsigned char maxBitsPerTable);
|
|
void _constructErrorTable();
|
|
|
|
private:
|
|
struct Table {
|
|
unsigned char peekBits;
|
|
std::vector<signed short> lookup;
|
|
};
|
|
|
|
Table _table0;
|
|
std::vector<Table> _tables;
|
|
bool _error;
|
|
};
|
|
|
|
#endif /* HUFFMAN_DECODER_H */
|