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/* Run-time scaletable computation for Xcftools
*
* This file was written by Henning Makholm <henning@makholm.net>
* It is hereby in the public domain.
*
* In jurisdictions that do not recognise grants of copyright to the
* public domain: I, the author and (presumably, in those jurisdictions)
* copyright holder, hereby permit anyone to distribute and use this code,
* in source code or binary form, with or without modifications. This
* permission is world-wide and irrevocable.
*
* Of course, I will not be liable for any errors or shortcomings in the
* code, since I give it away without asking any compenstations.
*
* If you use or distribute this code, I would appreciate receiving
* credit for writing it, in whichever way you find proper and customary.
*/
#include "pixels.h"
#ifndef PRECOMPUTED_SCALETABLE
uint8_t scaletable[256][256] ;
int ok_scaletable = 0 ;
void
mk_scaletable(void)
{
unsigned p, q, r ;
if( ok_scaletable ) return ;
for( p = 0 ; p < 128 ; p++ )
for( q = 0 ; q <= p ; q++ ) {
r = (p*q+127)/255 ;
scaletable[p][q] = scaletable[q][p] = r ;
scaletable[255-p][q] = scaletable[q][255-p] = q-r ;
scaletable[p][255-q] = scaletable[255-q][p] = p-r ;
scaletable[255-p][255-q] = scaletable[255-q][255-p] = (255-q)-(p-r) ;
}
ok_scaletable = 1 ;
}
#endif
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