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43 lines
1.3 KiB
43 lines
1.3 KiB
15 years ago
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/* Run-time scaletable computation for Xcftools
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*
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* Copyright (C) 2006 Henning Makholm
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "pixels.h"
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#ifndef PRECOMPUTED_SCALETABLE
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uint8_t scaletable[256][256] ;
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int ok_scaletable = 0 ;
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void
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mk_scaletable(void)
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{
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unsigned p, q, r ;
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if( ok_scaletable ) return ;
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for( p = 0 ; p < 128 ; p++ )
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for( q = 0 ; q <= p ; q++ ) {
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r = (p*q+127)/255 ;
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scaletable[p][q] = scaletable[q][p] = r ;
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scaletable[255-p][q] = scaletable[q][255-p] = q-r ;
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scaletable[p][255-q] = scaletable[255-q][p] = p-r ;
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scaletable[255-p][255-q] = scaletable[255-q][255-p] = (255-q)-(p-r) ;
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}
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ok_scaletable = 1 ;
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}
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#endif
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