File indexing completed on 2025-03-09 04:09:53

 /* 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