File indexing completed on 2024-05-12 15:59:36

 /*
  *  SPDX-FileCopyrightText: 2005 Adrian Page <adrian@pagenet.plus.com>
  *
  * SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #ifndef KO_INTEGER_MATHS_H
 #define KO_INTEGER_MATHS_H
 
 #include <cstdint>
 
 #ifndef UINT8_MAX
 #define UINT8_MAX 255u
 #endif
 
 #ifndef UINT8_MIN
 #define UINT8_MIN 0u
 #endif
 
 #ifndef UINT16_MAX
 #define UINT16_MAX 65535u
 #endif
 
 #ifndef UINT16_MIN
 #define UINT16_MIN 0u
 #endif
 
 #ifndef UINT32_MAX
 #define UINT32_MAX (4294967295u)
 #endif
 
 #ifndef UINT32_MIN
 #define UINT32_MIN 0u
 #endif
 
 #ifndef INT16_MAX
 #define INT16_MAX 32767
 #endif
 
 #ifndef INT16_MIN
 #define INT16_MIN -32768
 #endif
 
 typedef unsigned int uint;
 
 template<typename _T_, typename _T2_, typename _T3_>
 inline _T_ CLAMP(_T_ x, _T2_ l, _T3_ u)
 {
     if (x < l)
         return _T_(l);
     else if (x > u)
         return _T_(u);
     return x;
 }
 
 /// 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;
 }
 
 /// multiplication of two scale values
 /// A scale value is interpreted as 255 equaling 1.0 (such as seen in rgb8 triplets)
 /// thus "255*255=255" because 1.0*1.0=1.0
 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;
 }
 
 /// Approximation of (a * b * c + 32512) / 65025.0
 inline uint UINT8_MULT3(uint a, uint b, uint c)
 {
   uint t = a * b * c + 0x7F5B;
   return ((t >> 7) + t) >> 16;
 }
 
 /// Blending of two scale values as described by the alpha scale value
 /// A scale value is interpreted as 255 equaling 1.0 (such as seen in rgb8 triplets)
 /// Basically we do: a*alpha + b*(1-alpha)
 inline uint UINT8_BLEND(uint a, uint b, uint alpha)
 {
     // However the formula is 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)) * alpha + 0x80u;
     c = ((c >> 8) + c) >> 8;
     return 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