text: /*
   * 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.
   *
   * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
   * All rights reserved.
   *
   * The Original Code is: some of this file.
   *
   * */
  
  /** \file
   * \ingroup bli
   */
  
  #include "BLI_math_base.h"
  #include "BLI_math_color.h"
  #include "BLI_utildefines.h"
  
  #include "math.h"
  
  #ifndef __MATH_COLOR_INLINE_C__
  #  define __MATH_COLOR_INLINE_C__
  
  /******************************** Color Space ********************************/
  
  #  ifdef __SSE2__
  
  MALWAYS_INLINE __m128 srgb_to_linearrgb_v4_simd(const __m128 c)
  {
    __m128 cmp = _mm_cmplt_ps(c, _mm_set1_ps(0.04045f));
    __m128 lt = _mm_max_ps(_mm_mul_ps(c, _mm_set1_ps(1.0f / 12.92f)), _mm_set1_ps(0.0f));
    __m128 gtebase = _mm_mul_ps(_mm_add_ps(c, _mm_set1_ps(0.055f)),
                                _mm_set1_ps(1.0f / 1.055f)); /* fma */
    __m128 gte = _bli_math_fastpow24(gtebase);
    return _bli_math_blend_sse(cmp, lt, gte);
  }
  
  MALWAYS_INLINE __m128 linearrgb_to_srgb_v4_simd(const __m128 c)
  {
    __m128 cmp = _mm_cmplt_ps(c, _mm_set1_ps(0.0031308f));
    __m128 lt = _mm_max_ps(_mm_mul_ps(c, _mm_set1_ps(12.92f)), _mm_set1_ps(0.0f));
    __m128 gte = _mm_add_ps(_mm_mul_ps(_mm_set1_ps(1.055f), _bli_math_fastpow512(c)),
                            _mm_set1_ps(-0.055f));
    return _bli_math_blend_sse(cmp, lt, gte);
  }
  
  MINLINE void srgb_to_linearrgb_v3_v3(float linear[3], const float srgb[3])
  {
    float r[4] = {srgb[0], srgb[1], srgb[2], 1.0f};
    __m128 *rv = (__m128 *)&r;
    *rv = srgb_to_linearrgb_v4_simd(*rv);
    linear[0] = r[0];
    linear[1] = r[1];
    linear[2] = r[2];
  }
  
  MINLINE void linearrgb_to_srgb_v3_v3(float srgb[3], const float linear[3])
  {
    float r[4] = {linear[0], linear[1], linear[2], 1.0f};
    __m128 *rv = (__m128 *)&r;
    *rv = linearrgb_to_srgb_v4_simd(*rv);
    srgb[0] = r[0];
    srgb[1] = r[1];
    srgb[2] = r[2];
  }
  
  #  else  /* __SSE2__ */
  
  MINLINE void srgb_to_linearrgb_v3_v3(float linear[3], const float srgb[3])
  {
    linear[0] = srgb_to_linearrgb(srgb[0]);
    linear[1] = srgb_to_linearrgb(srgb[1]);
    linear[2] = srgb_to_linearrgb(srgb[2]);
  }
  
  MINLINE void linearrgb_to_srgb_v3_v3(float srgb[3], const float linear[3])
  {
    srgb[0] = linearrgb_to_srgb(linear[0]);
    srgb[1] = linearrgb_to_srgb(linear[1]);
    srgb[2] = linearrgb_to_srgb(linear[2]);
  }
  #  endif /* __SSE2__ */
  
  MINLINE void srgb_to_linearrgb_v4(float linear[4], const float srgb[4])
  {
    srgb_to_linearrgb_v3_v3(linear, srgb);
    linear[3] = srgb[3];
  }
  
  MINLINE void linearrgb_to_srgb_v4(float srgb[4], const float linear[4])
  {
    linearrgb_to_srgb_v3_v3(srgb, linear);
    srgb[3] = linear[3];
  }
  
  MINLINE void linearrgb_to_srgb_uchar3(unsigned char srgb[3], const float linear[3])
  {
    float srgb_f[3];
  
    linearrgb_to_srgb_v3_v3(srgb_f, linear);
    unit_float_to_uchar_clamp_v3(srgb, srgb_f);
  }
  
  MINLINE void linearrgb_to_srgb_uchar4(unsigned char srgb[4], const float linear[4])
  {
    float srgb_f[4];
  
    linearrgb_to_srgb_v4(srgb_f, linear);
    unit_float_to_uchar_clamp_v4(srgb, srgb_f);
  }
  
  /* predivide versions to work on associated/pre-multiplied alpha. if this should
   * be done or not depends on the background the image will be composited over,
   * ideally you would never do color space conversion on an image with alpha
   * because it is ill defined */
  
  MINLINE void srgb_to_linearrgb_predivide_v4(float linear[4], const float srgb[4])
  {
    float alpha, inv_alpha;
  
    if (srgb[3] == 1.0f || srgb[3] == 0.0f) {
      alpha = 1.0f;
      inv_alpha = 1.0f;
    }
    else {
      alpha = srgb[3];
      inv_alpha = 1.0f / alpha;
    }
  
    linear[0] = srgb[0] * inv_alpha;
    linear[1] = srgb[1] * inv_alpha;
    linear[2] = srgb[2] * inv_alpha;
    linear[3] = srgb[3];
    srgb_to_linearrgb_v3_v3(linear, linear);
    linear[0] *= alpha;
    linear[1] *= alpha;
    linear[2] *= alpha;
  }
  
  MINLINE void linearrgb_to_srgb_predivide_v4(float srgb[4], const float linear[4])
  {
    float alpha, inv_alpha;
  
    if (linear[3] == 1.0f || linear[3] == 0.0f) {
      alpha = 1.0f;
      inv_alpha = 1.0f;
    }
    else {
      alpha = linear[3];
      inv_alpha = 1.0f / alpha;
    }
  
    srgb[0] = linear[0] * inv_alpha;
    srgb[1] = linear[1] * inv_alpha;
    srgb[2] = linear[2] * inv_alpha;
    srgb[3] = linear[3];
    linearrgb_to_srgb_v3_v3(srgb, srgb);
    srgb[0] *= alpha;
    srgb[1] *= alpha;
    srgb[2] *= alpha;
  }
  
  /* LUT accelerated conversions */
  
  extern float BLI_color_from_srgb_table[256];
  extern unsigned short BLI_color_to_srgb_table[0x10000];
  
  MINLINE unsigned short to_srgb_table_lookup(const float f)
  {
  
    union {
      float f;
      unsigned short us[2];
    } tmp;
    tmp.f = f;
  #  ifdef __BIG_ENDIAN__
    return BLI_color_to_srgb_table[tmp.us[0]];
  #  else
    return BLI_color_to_srgb_table[tmp.us[1]];
  #  endif
  }
  
  MINLINE void linearrgb_to_srgb_ushort4(unsigned short srgb[4], const float linear[4])
  {
    srgb[0] = to_srgb_table_lookup(linear[0]);
    srgb[1] = to_srgb_table_lookup(linear[1]);
    srgb[2] = to_srgb_table_lookup(linear[2]);
    srgb[3] = unit_float_to_ushort_clamp(linear[3]);
  }
  
  MINLINE void srgb_to_linearrgb_uchar4(float linear[4], const unsigned char srgb[4])
  {
    linear[0] = BLI_color_from_srgb_table[srgb[0]];
    linear[1] = BLI_color_from_srgb_table[srgb[1]];
    linear[2] = BLI_color_from_srgb_table[srgb[2]];
    linear[3] = srgb[3] * (1.0f / 255.0f);
  }
  
  MINLINE void srgb_to_linearrgb_uchar4_predivide(float linear[4], const unsigned char srgb[4])
  {
    float fsrgb[4];
    int i;
  
    if (srgb[3] == 255 || srgb[3] == 0) {
      srgb_to_linearrgb_uchar4(linear, srgb);
      return;
    }
  
    for (i = 0; i < 4; i++) {
      fsrgb[i] = srgb[i] * (1.0f / 255.0f);
    }
  
    srgb_to_linearrgb_predivide_v4(linear, fsrgb);
  }
  
  MINLINE void rgba_uchar_args_set(
      uchar col[4], const uchar r, const uchar g, const uchar b, const uchar a)
  {
    col[0] = r;
    col[1] = g;
    col[2] = b;
    col[3] = a;
  }
  
  MINLINE void rgba_float_args_set(
      float col[4], const float r, const float g, const float b, const float a)
  {
    col[0] = r;
    col[1] = g;
    col[2] = b;
    col[3] = a;
  }
  
  MINLINE void rgba_uchar_args_test_set(
      uchar col[4], const uchar r, const uchar g, const uchar b, const uchar a)
  {
    if (col[3] == 0) {
      col[0] = r;
      col[1] = g;
      col[2] = b;
      col[3] = a;
    }
  }
  
  MINLINE void cpack_cpy_3ub(unsigned char r_col[3], const unsigned int pack)
  {
    r_col[0] = ((pack) >> 0) & 0xFF;
    r_col[1] = ((pack) >> 8) & 0xFF;
    r_col[2] = ((pack) >> 16) & 0xFF;
  }
  
  /** \name RGB/Grayscale Functions
   *
   * \warning
   * These are only an approximation,
   * in almost _all_ cases, #IMB_colormanagement_get_luminance should be used instead. However for
   * screen-only colors which don't depend on the currently loaded profile - this is preferred.
   * Checking theme colors for contrast, etc. Basically anything outside the render pipeline.
   *
   * \{ */
  
  /**
   * ITU-R BT.709 primaries
   * https://en.wikipedia.org/wiki/Relative_luminance
   *
   * Real values are:
   * ``Y = 0.2126390059(R) + 0.7151686788(G) + 0.0721923154(B)``
   * according to: "Derivation of Basic Television Color Equations", RP 177-1993
   *
   * As this sums slightly above 1.0, the document recommends to use:
   * ``0.2126(R) + 0.7152(G) + 0.0722(B)``, as used here.
   *
   * The high precision values are used to calculate the rounded byte weights so they add up to 255:
   * ``54(R) + 182(G) + 19(B)``
   */
  MINLINE float rgb_to_grayscale(const float rgb[3])
  {
    return (0.2126f * rgb[0]) + (0.7152f * rgb[1]) + (0.0722f * rgb[2]);
  }
  
  MINLINE unsigned char rgb_to_grayscale_byte(const unsigned char rgb[3])
  {
    return (unsigned char)(((54 * (unsigned short)rgb[0]) + (182 * (unsigned short)rgb[1]) +
                            (19 * (unsigned short)rgb[2])) /
                           255);
  }
  
  /** \} */
  
  MINLINE int compare_rgb_uchar(const unsigned char col_a[3],
                                const unsigned char col_b[3],
                                const int limit)
  {
    const int r = (int)col_a[0] - (int)col_b[0];
    if (ABS(r) < limit) {
      const int g = (int)col_a[1] - (int)col_b[1];
      if (ABS(g) < limit) {
        const int b = (int)col_a[2] - (int)col_b[2];
        if (ABS(b) < limit) {
          return 1;
        }
      }
    }
  
    return 0;
  }
  
  /* Using a triangle distribution which gives a more final uniform noise.
   * See Banding in Games:A Noisy Rant(revision 5) Mikkel Gjøl, Playdead (slide 27) */
  /* Return triangle noise in [-0.5..1.5[ range */
  MINLINE float dither_random_value(float s, float t)
  {
    /* Original code from https://www.shadertoy.com/view/4t2SDh */
    /* The noise reshaping technique does not work on CPU.
     * We generate and merge two distribution instead */
    /* Uniform noise in [0..1[ range */
    float nrnd0 = sinf(s * 12.9898f + t * 78.233f) * 43758.5453f;
    float nrnd1 = sinf(s * 19.9898f + t * 119.233f) * 43798.5453f;
    nrnd0 -= floorf(nrnd0);
    nrnd1 -= floorf(nrnd1);
    /* Convert uniform distribution into triangle-shaped distribution. */
    return nrnd0 + nrnd1 - 0.5f;
  }
  
  MINLINE void float_to_byte_dither_v3(
      unsigned char b[3], const float f[3], float dither, float s, float t)
  {
    float dither_value = dither_random_value(s, t) * 0.0033f * dither;
  
    b[0] = unit_float_to_uchar_clamp(dither_value + f[0]);
    b[1] = unit_float_to_uchar_clamp(dither_value + f[1]);
    b[2] = unit_float_to_uchar_clamp(dither_value + f[2]);
  }
  
  /**************** Alpha Transformations *****************/
  
  MINLINE void premul_to_straight_v4_v4(float straight[4], const float premul[4])
  {
    if (premul[3] == 0.0f || premul[3] == 1.0f) {
      straight[0] = premul[0];
      straight[1] = premul[1];
      straight[2] = premul[2];
      straight[3] = premul[3];
    }
    else {
      const float alpha_inv = 1.0f / premul[3];
      straight[0] = premul[0] * alpha_inv;
      straight[1] = premul[1] * alpha_inv;
      straight[2] = premul[2] * alpha_inv;
      straight[3] = premul[3];
    }
  }
  
  MINLINE void premul_to_straight_v4(float color[4])
  {
    premul_to_straight_v4_v4(color, color);
  }
  
  MINLINE void straight_to_premul_v4_v4(float premul[4], const float straight[4])
  {
    const float alpha = straight[3];
    premul[0] = straight[0] * alpha;
    premul[1] = straight[1] * alpha;
    premul[2] = straight[2] * alpha;
    premul[3] = straight[3];
  }
  
  MINLINE void straight_to_premul_v4(float color[4])
  {
    straight_to_premul_v4_v4(color, color);
  }
  
  MINLINE void straight_uchar_to_premul_float(float result[4], const unsigned char color[4])
  {
    const float alpha = color[3] * (1.0f / 255.0f);
    const float fac = alpha * (1.0f / 255.0f);
  
    result[0] = color[0] * fac;
    result[1] = color[1] * fac;
    result[2] = color[2] * fac;
    result[3] = alpha;
  }
  
  MINLINE void premul_float_to_straight_uchar(unsigned char *result, const float color[4])
  {
    if (color[3] == 0.0f || color[3] == 1.0f) {
      result[0] = unit_float_to_uchar_clamp(color[0]);
      result[1] = unit_float_to_uchar_clamp(color[1]);
      result[2] = unit_float_to_uchar_clamp(color[2]);
      result[3] = unit_float_to_uchar_clamp(color[3]);
    }
    else {
      const float alpha_inv = 1.0f / color[3];
  
      /* hopefully this would be optimized */
      result[0] = unit_float_to_uchar_clamp(color[0] * alpha_inv);
      result[1] = unit_float_to_uchar_clamp(color[1] * alpha_inv);
      result[2] = unit_float_to_uchar_clamp(color[2] * alpha_inv);
      result[3] = unit_float_to_uchar_clamp(color[3]);
    }
  }
  
  #endif /* __MATH_COLOR_INLINE_C__ */
  