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/*
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stdio.h>
#include <inttypes.h>
#define F 100
#define SIZE 2048
static uint64_t int_sqrt(uint64_t a)
{
uint64_t ret=0;
int s;
uint64_t ret_sq=0;
for(s=31; s>=0; s--){
uint64_t b= ret_sq + (1ULL<<(s*2)) + (ret<<s)*2;
if(b<=a){
ret_sq=b;
ret+= 1ULL<<s;
}
}
return ret;
}
int main(int argc,char* argv[]){
int i, j;
uint64_t sse=0;
uint64_t dev;
FILE *f[2];
uint8_t buf[2][SIZE];
if(argc!=3){
printf("tiny_psnr <file1> <file2>\n");
return -1;
}
f[0]= fopen(argv[1], "r");
f[1]= fopen(argv[2], "r");
for(i=0;;){
if( fread(buf[0], SIZE, 1, f[0]) != 1) break;
if( fread(buf[1], SIZE, 1, f[1]) != 1) break;
for(j=0; j<SIZE; i++,j++){
const int a= buf[0][j];
const int b= buf[1][j];
sse += (a-b) * (a-b);
}
}
dev= int_sqrt((sse*F*F)/i);
//FIXME someone should write a integer fixpoint log() function for bitexact PSNR scores ...
printf("stddev:%3d.%02d bytes:%d\n", (int)(dev/F), (int)(dev%F), i);
return 0;
}
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