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/*
This file is part of Page Layout Detection Tools.
This code is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This code 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this code; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <util/bitutil.h>
namespace pagetools{
BitUtil *BitUtil::instance_=0;
const unsigned char*
BitUtil::bitcount(){
if(!instance_){
instance_=new BitUtil;
}
return instance_->bitcount_;
}
const unsigned char*
BitUtil::invbits(){
if(!instance_){
instance_=new BitUtil;
}
return instance_->invbits_;
}
BitUtil::BitUtil(){
bitcount_=new unsigned char[256];
invbits_=new unsigned char[256];
unsigned int i;
for(i=0; i<256; i++){
unsigned int j=i, cnt=0;
do{
cnt+=j&1;
}while(j>>=1);
char x=(i<<4)|(i>>4);
x=((x&0xCC)>>2)|((x&0x33)<<2);
x=((x&0xAA)>>1)|((x&0x55)<<1);
bitcount_[i]=cnt;
invbits_[i]=x;
}
}
}
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