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121 lines
2.7 KiB
121 lines
2.7 KiB
/*
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Copyright (C) 2000 Stefan Westerfeld
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stefan@space.twc.de
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with this library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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*/
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#include "huffmanlookup.h"
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#include <assert.h>
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struct HuffmanLookup::decodeData HuffmanLookup::qdecode[32][256];
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/* for initialization */
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static HuffmanLookup l;
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HuffmanLookup::HuffmanLookup()
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{
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int table,p,x,y;
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for(table = 0; table < 32; table++)
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{
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// 8 bits pattern
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for(p = 0; p < 256; p++)
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{
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bits = 24;
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pattern = (p << 16);
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huffmandecoder_1(&Mpegtoraw::ht[table], &x,&y);
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int used = 24 - bits;
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qdecode[table][p].skip = (used <= 8)?used:0;
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qdecode[table][p].x = x;
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qdecode[table][p].y = y;
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}
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}
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}
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int HuffmanLookup::wgetbit()
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{
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return (pattern >> --bits) & 1;
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}
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int HuffmanLookup::wgetbits (int b)
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{
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bits -= b;
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return (pattern >> bits) & ((1 << b) - 1);
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}
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void HuffmanLookup::huffmandecoder_1(const HUFFMANCODETABLE *h, int *x, int *y)
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{
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typedef unsigned int HUFFBITS;
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HUFFBITS level=(1<<(sizeof(HUFFBITS)*8-1));
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int point=0;
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/* Lookup in Huffman table. */
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for(;;)
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{
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if(h->val[point][0]==0)
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{ /*end of tree*/
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int xx,yy;
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xx=h->val[point][1]>>4;
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yy=h->val[point][1]&0xf;
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if(h->linbits)
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{
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if((h->xlen)==(unsigned)xx)xx+=wgetbits(h->linbits);
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if(xx)if(wgetbit())xx=-xx;
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if((h->ylen)==(unsigned)yy)yy+=wgetbits(h->linbits);
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if(yy)if(wgetbit())yy=-yy;
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}
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else
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{
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if(xx)if(wgetbit())xx=-xx;
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if(yy)if(wgetbit())yy=-yy;
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}
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*x=xx;*y=yy;
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break;
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}
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point+=h->val[point][wgetbit()];
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level>>=1;
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if(!(level || ((unsigned)point<Mpegtoraw::ht->treelen)))
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{
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int xx,yy;
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xx=(h->xlen<<1);// set x and y to a medium value as a simple concealment
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yy=(h->ylen<<1);
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// h->xlen and h->ylen can't be 1 under tablename 32
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// if(xx)
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if(wgetbit())xx=-xx;
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// if(yy)
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if(wgetbit())yy=-yy;
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*x=xx;*y=yy;
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break;
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}
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}
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}
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