text: /* Copyright  (C) 2010-2020 The RetroArch team
   *
   * ---------------------------------------------------------------------------------------
   * The following license statement only applies to this file (retro_math.h).
   * ---------------------------------------------------------------------------------------
   *
   * Permission is hereby granted, free of charge,
   * to any person obtaining a copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation the rights to
   * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
   * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
   * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #ifndef _LIBRETRO_COMMON_MATH_H
  #define _LIBRETRO_COMMON_MATH_H
  
  #include <stdint.h>
  
  #if defined(_WIN32) && !defined(_XBOX)
  #define WIN32_LEAN_AND_MEAN
  #include <windows.h>
  #elif defined(_WIN32) && defined(_XBOX)
  #include <Xtl.h>
  #endif
  
  #include <limits.h>
  
  #ifdef _MSC_VER
  #include <compat/msvc.h>
  #endif
  #include <retro_inline.h>
  
  #ifndef M_PI
  #if !defined(USE_MATH_DEFINES)
  #define M_PI 3.14159265358979323846264338327
  #endif
  #endif
  
  #ifndef MAX
  #define MAX(a, b) ((a) > (b) ? (a) : (b))
  #endif
  
  #ifndef MIN
  #define MIN(a, b) ((a) < (b) ? (a) : (b))
  #endif
  
  /**
   * next_pow2:
   * @v         : initial value
   *
   * Get next power of 2 value based on  initial value.
   *
   * Returns: next power of 2 value (derived from @v).
   **/
  static INLINE uint32_t next_pow2(uint32_t v)
  {
     v--;
     v |= v >> 1;
     v |= v >> 2;
     v |= v >> 4;
     v |= v >> 8;
     v |= v >> 16;
     v++;
     return v;
  }
  
  /**
   * prev_pow2:
   * @v         : initial value
   *
   * Get previous power of 2 value based on initial value.
   *
   * Returns: previous power of 2 value (derived from @v).
   **/
  static INLINE uint32_t prev_pow2(uint32_t v)
  {
     v |= v >> 1;
     v |= v >> 2;
     v |= v >> 4;
     v |= v >> 8;
     v |= v >> 16;
     return v - (v >> 1);
  }
  
  /**
   * clamp:
   * @v         : initial value
   *
   * Get the clamped value based on initial value.
   *
   * Returns: clamped value (derived from @v).
   **/
  static INLINE float clamp_value(float v, float min, float max)
  {
     return v <= min ? min : v >= max ? max : v;
  }
  
  /**
   * saturate_value:
   * @v         : initial value
   *
   * Get the clamped 0.0-1.0 value based on initial value.
   *
   * Returns: clamped 0.0-1.0 value (derived from @v).
   **/
  static INLINE float saturate_value(float v)
  {
     return clamp_value(v, 0.0f, 1.0f);
  }
  
  /**
   * dot_product:
   * @a         : left hand vector value
   * @b         : right hand vector value
   *
   * Get the dot product of the two passed in vectors.
   *
   * Returns: dot product value (derived from @a and @b).
   **/
  static INLINE float dot_product(const float* a, const float* b) 
  {
     return (a[0] * b[0]) + (a[1] * b[1]) + (a[2] * b[2]);
  }
  
  /**
   * convert_rgb_to_yxy:
   * @rgb         : in RGB colour space value
   * @Yxy         : out Yxy colour space value
   *
   * Convert from RGB colour space to Yxy colour space.
   *
   * Returns: Yxy colour space value (derived from @rgb).
   **/
  static INLINE void convert_rgb_to_yxy(const float* rgb, float* Yxy) 
  {
     float inv;
     float xyz[3];
     float one[3]        = {1.0, 1.0, 1.0};
     float rgb_xyz[3][3] = {
        {0.4124564, 0.3575761, 0.1804375},
        {0.2126729, 0.7151522, 0.0721750},
        {0.0193339, 0.1191920, 0.9503041}
     };
  
     xyz[0]              = dot_product(rgb_xyz[0], rgb);
     xyz[1]              = dot_product(rgb_xyz[1], rgb);
     xyz[2]              = dot_product(rgb_xyz[2], rgb);
  
     inv                 = 1.0f / dot_product(xyz, one);
     Yxy[0]              = xyz[1]; 
     Yxy[1]              = xyz[0] * inv;
     Yxy[2]              = xyz[1] * inv;
  }
   
  /**
   * convert_yxy_to_rgb:
   * @rgb         : in Yxy colour space value
   * @Yxy         : out rgb colour space value
   *
   * Convert from Yxy colour space to rgb colour space.
   *
   * Returns: rgb colour space value (derived from @Yxy).
   **/
  static INLINE void convert_yxy_to_rgb(const float* Yxy, float* rgb)
  {
     float xyz[3];
     float xyz_rgb[3][3] = {
        {3.2404542, -1.5371385, -0.4985314},
        {-0.9692660, 1.8760108,  0.0415560},
        {0.0556434, -0.2040259, 1.0572252}
     };
     xyz[0]              = Yxy[0] * Yxy[1] / Yxy[2];
     xyz[1]              = Yxy[0];
     xyz[2]              = Yxy[0] * (1.0 - Yxy[1] - Yxy[2]) / Yxy[2];
  
     rgb[0]              = dot_product(xyz_rgb[0], xyz);
     rgb[1]              = dot_product(xyz_rgb[1], xyz);
     rgb[2]              = dot_product(xyz_rgb[2], xyz);
  }
  
  #endif
  