text: /*
   * Copyright 2016 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #ifndef SkPM4fPriv_DEFINED
  #define SkPM4fPriv_DEFINED
  
  #include "SkColorPriv.h"
  #include "SkPM4f.h"
  
  extern bool gTreatSkColorAsSRGB;
  
  static inline float get_alpha(const Sk4f& f4) {
      return f4[SkPM4f::A];
  }
  
  static inline Sk4f set_alpha(const Sk4f& f4, float alpha) {
      static_assert(3 == SkPM4f::A, "");
      return Sk4f(f4[0], f4[1], f4[2], alpha);
  }
  
  static inline uint32_t to_4b(const Sk4f& f4) {
      uint32_t b4;
      SkNx_cast<uint8_t>(f4).store((uint8_t*)&b4);
      return b4;
  }
  
  static inline Sk4f to_4f(uint32_t b4) {
      return SkNx_cast<float>(Sk4b::Load((const uint8_t*)&b4));
  }
  
  static inline Sk4f to_4f_rgba(uint32_t b4) {
      return swizzle_rb_if_bgra(to_4f(b4));
  }
  
  static inline Sk4f srgb_to_linear(const Sk4f& s4) {
      return set_alpha(s4 * s4, get_alpha(s4));
  }
  
  static inline Sk4f linear_to_srgb(const Sk4f& l4) {
      return set_alpha(l4.sqrt(), get_alpha(l4));
  }
  
  static inline float srgb_to_linear(float x) {
      return x * x;
  }
  
  static inline float linear_to_srgb(float x) {
      return sqrtf(x);
  }
  
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  
  static inline Sk4f Sk4f_fromL32(uint32_t src) {
      return to_4f(src) * Sk4f(1.0f/255);
  }
  
  static inline Sk4f Sk4f_fromS32(uint32_t src) {
      return srgb_to_linear(to_4f(src) * Sk4f(1.0f/255));
  }
  
  static inline uint32_t Sk4f_toL32(const Sk4f& x4) {
      return to_4b(x4 * Sk4f(255) + Sk4f(0.5f));
  }
  
  static inline uint32_t Sk4f_toS32(const Sk4f& x4) {
      return to_4b(linear_to_srgb(x4) * Sk4f(255) + Sk4f(0.5f));
  }
  
  #endif
  