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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.
*/
#include "huffmanlookup.h"
#include <assert.h>
struct HuffmanLookup::decodeData HuffmanLookup::qdecode[32][256];
/* for initialization */
static HuffmanLookup l;
HuffmanLookup::HuffmanLookup()
{
int table,p,x,y;
for(table = 0; table < 32; table++)
{
// 8 bits pattern
for(p = 0; p < 256; p++)
{
bits = 24;
pattern = (p << 16);
huffmandecoder_1(&Mpegtoraw::ht[table], &x,&y);
int used = 24 - bits;
qdecode[table][p].skip = (used <= 8)?used:0;
qdecode[table][p].x = x;
qdecode[table][p].y = y;
}
}
}
int HuffmanLookup::wgetbit()
{
return (pattern >> --bits) & 1;
}
int HuffmanLookup::wgetbits (int b)
{
bits -= b;
return (pattern >> bits) & ((1 << b) - 1);
}
void HuffmanLookup::huffmandecoder_1(const HUFFMANCODETABLE *h, int *x, int *y)
{
typedef unsigned int HUFFBITS;
HUFFBITS level=(1<<(sizeof(HUFFBITS)*8-1));
int point=0;
/* Lookup in Huffman table. */
for(;;)
{
if(h->val[point][0]==0)
{ /*end of tree*/
int xx,yy;
xx=h->val[point][1]>>4;
yy=h->val[point][1]&0xf;
if(h->linbits)
{
if((h->xlen)==(unsigned)xx)xx+=wgetbits(h->linbits);
if(xx)if(wgetbit())xx=-xx;
if((h->ylen)==(unsigned)yy)yy+=wgetbits(h->linbits);
if(yy)if(wgetbit())yy=-yy;
}
else
{
if(xx)if(wgetbit())xx=-xx;
if(yy)if(wgetbit())yy=-yy;
}
*x=xx;*y=yy;
break;
}
point+=h->val[point][wgetbit()];
level>>=1;
if(!(level || ((unsigned)point<Mpegtoraw::ht->treelen)))
{
int xx,yy;
xx=(h->xlen<<1);// set x and y to a medium value as a simple concealment
yy=(h->ylen<<1);
// h->xlen and h->ylen can't be 1 under tablename 32
// if(xx)
if(wgetbit())xx=-xx;
// if(yy)
if(wgetbit())yy=-yy;
*x=xx;*y=yy;
break;
}
}
}
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