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/*
Copyright (C) 2000 Stefan Westerfeld
stefan@space.twc.de
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef __HUFFMANLOOKUP_H
#define __HUFFMANLOOKUP_H
#include "mpegsound.h"
/*
* This class speeds up the huffman table decoding by largely replacing it
* by a table lookup. It uses the fact that the huffman tables don't change,
* and that given a byte of the bitstream, we can predict what the result
* will be (without reading it bit by bit).
*/
class HuffmanLookup {
private:
long pattern, bits;
int wgetbit();
int wgetbits (int b);
void huffmandecoder_1(const HUFFMANCODETABLE *h,int *x, int *y);
ATTR_ALIGN(64) static struct decodeData {
int x : 8;
int y : 8;
int skip : 16;
} qdecode[32][256];
public:
HuffmanLookup();
static int decode(int table, int pattern, int* x, int* y)
{
*x = qdecode[table][pattern].x;
*y = qdecode[table][pattern].y;
return qdecode[table][pattern].skip;
}
};
#endif
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