forked from openkylin/gimp
78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
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/*
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* DDS GIMP plugin
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*
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* Copyright (C) 2004-2012 Shawn Kirst <skirst@gmail.com>,
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* with parts (C) 2003 Arne Reuter <homepage@arnereuter.de> where specified.
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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 the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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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, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef __IMATH_H__
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#define __IMATH_H__
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#ifndef MIN
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# ifdef __GNUC__
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# define MIN(a, b) ({typeof(a) _a=(a); typeof(b) _b=(b); _a < _b ? _a : _b;})
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# else
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# define MIN(a, b) ((a) < (b) ? (a) : (b))
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# endif
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#endif
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#ifndef MAX
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# ifdef __GNUC__
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# define MAX(a, b) ({typeof(a) _a=(a); typeof(b) _b=(b); _a > _b ? _a : _b;})
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# else
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# define MAX(a, b) ((a) > (b) ? (a) : (b))
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# endif
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#endif
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#define IS_POW2(x) (!((x) & ((x) - 1)))
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#define IS_MUL4(x) (((x) & 3) == 0)
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/* round integer x up to next multiple of 4 */
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#define RND_MUL4(x) ((x) + (4 - ((x) & 3)))
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static inline int
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mul8bit (int a,
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int b)
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{
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int t = a * b + 128;
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return (t + (t >> 8)) >> 8;
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}
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static inline int
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blerp (int a,
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int b,
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int x)
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{
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return a + mul8bit(b - a, x);
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}
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static inline int
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icerp (int a,
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int b,
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int c,
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int d,
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int x)
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{
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int p = (d - c) - (a - b);
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int q = (a - b) - p;
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int r = c - a;
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return (x * (x * (x * p + (q << 7)) + (r << 14)) + (b << 21)) >> 21;
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}
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#endif /* __IMATH_H__ */
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