1 files changed, 111 insertions, 0 deletions
diff --git a/chalk/sdk/kis_integer_maths.h b/chalk/sdk/kis_integer_maths.h
new file mode 100644
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+++ b/chalk/sdk/kis_integer_maths.h
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+/*
+ *  Copyright (c) 2005 Adrian Page <adrian@pagenet.plus.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef KIS_INTEGER_MATHS_H
+#define KIS_INTEGER_MATHS_H
+
+#define UINT8_MAX 255u
+#define UINT8_MIN 0u
+
+#define UINT16_MAX 65535u
+#define UINT16_MIN 0u
+
+#define UINT32_MAX (4294967295u)
+#define UINT32_MIN 0u
+
+#define INT16_MAX 32767
+#define INT16_MIN -32768
+
+/// take a and scale it up by 256*b/255
+inline uint UINT8_SCALEBY(uint a, uint b)
+{
+    uint c = a * b + 0x80u;
+    return (c >> 8) + c;
+}
+
+inline uint UINT8_MULT(uint a, uint b)
+{
+    uint c = a * b + 0x80u;
+    return ((c >> 8) + c) >> 8;
+}
+
+inline uint UINT8_DIVIDE(uint a, uint b)
+{
+    uint c = (a * UINT8_MAX + (b / 2u)) / b;
+    return c;
+}
+
+inline uint UINT8_BLEND(uint a, uint b, uint alpha)
+{
+    // Basically we do a*alpha + b*(1-alpha)
+    // However refactored to (a-b)*alpha + b  since that saves a multiplication
+    // Signed arithmetic is needed since a-b might be negative
+    int c = ((int(a) - int(b)) * int(alpha)) >> 8;
+
+    return uint(c + b);
+}
+
+inline uint UINT16_MULT(uint a, uint b)
+{
+    uint c = a * b + 0x8000u;
+    return ((c >> 16) + c) >> 16;
+}
+
+inline int INT16_MULT(int a, int b)
+{
+    return (a*b) / INT16_MAX;
+}
+
+inline uint UINT16_DIVIDE(uint a, uint b)
+{
+    uint c = (a * UINT16_MAX + (b / 2u)) / b;
+    return c;
+}
+
+inline uint UINT16_BLEND(uint a, uint b, uint alpha)
+{
+    // Basically we do a*alpha + b*(1-alpha)
+    // However refactored to (a-b)*alpha + b  since that saves a multiplication
+    // Signed arithmetic is needed since a-b might be negative
+    int c = ((int(a) - int(b)) * int(alpha)) >> 16;
+    return uint(c + b);
+}
+
+inline uint UINT8_TO_UINT16(uint c)
+{
+    return c | (c<<8);
+}
+
+inline uint UINT16_TO_UINT8(uint c)
+{
+    //return round(c / 257.0);
+    //For all UINT16 this calculation is the same and a lot faster (off by c/65656 which for every c is 0)
+    c = c - (c >> 8) + 128;
+    return c >>8;
+}
+
+inline int INT16_BLEND(int a, int b, uint alpha)
+{
+    // Basically we do a*alpha + b*(1-alpha)
+    // However refactored to (a-b)*alpha + b  since that saves a multiplication
+    int c = ((int(a) - int(b)) * int(alpha)) >> 16;
+    return c + b;
+}
+
+#endif
+