text: /*
   * Copyright 2015 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #ifndef SkNx_neon_DEFINED
  #define SkNx_neon_DEFINED
  
  #define SKNX_IS_FAST
  
  // ARMv8 has vrndmq_f32 to floor 4 floats.  Here we emulate it:
  //   - roundtrip through integers via truncation
  //   - subtract 1 if that's too big (possible for negative values).
  // This restricts the domain of our inputs to a maximum somehwere around 2^31.  Seems plenty big.
  static inline float32x4_t armv7_vrndmq_f32(float32x4_t v) {
      auto roundtrip = vcvtq_f32_s32(vcvtq_s32_f32(v));
      auto too_big = vcgtq_f32(roundtrip, v);
      return vsubq_f32(roundtrip, (float32x4_t)vandq_u32(too_big, (uint32x4_t)vdupq_n_f32(1)));
  }
  
  // Well, this is absurd.  The shifts require compile-time constant arguments.
  
  #define SHIFT8(op, v, bits) switch(bits) { \
      case  1: return op(v,  1);  case  2: return op(v,  2);  case  3: return op(v,  3); \
      case  4: return op(v,  4);  case  5: return op(v,  5);  case  6: return op(v,  6); \
      case  7: return op(v,  7); \
      } return fVec
  
  #define SHIFT16(op, v, bits) if (bits < 8) { SHIFT8(op, v, bits); } switch(bits) { \
                                  case  8: return op(v,  8);  case  9: return op(v,  9); \
      case 10: return op(v, 10);  case 11: return op(v, 11);  case 12: return op(v, 12); \
      case 13: return op(v, 13);  case 14: return op(v, 14);  case 15: return op(v, 15); \
      } return fVec
  
  #define SHIFT32(op, v, bits) if (bits < 16) { SHIFT16(op, v, bits); } switch(bits) { \
      case 16: return op(v, 16);  case 17: return op(v, 17);  case 18: return op(v, 18); \
      case 19: return op(v, 19);  case 20: return op(v, 20);  case 21: return op(v, 21); \
      case 22: return op(v, 22);  case 23: return op(v, 23);  case 24: return op(v, 24); \
      case 25: return op(v, 25);  case 26: return op(v, 26);  case 27: return op(v, 27); \
      case 28: return op(v, 28);  case 29: return op(v, 29);  case 30: return op(v, 30); \
      case 31: return op(v, 31); } return fVec
  
  template <>
  class SkNx<2, float> {
  public:
      SkNx(float32x2_t vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(float val)           : fVec(vdup_n_f32(val)) {}
      static SkNx Load(const void* ptr) { return vld1_f32((const float*)ptr); }
      SkNx(float a, float b) { fVec = (float32x2_t) { a, b }; }
  
      void store(void* ptr) const { vst1_f32((float*)ptr, fVec); }
  
      SkNx invert() const {
          float32x2_t est0 = vrecpe_f32(fVec),
                      est1 = vmul_f32(vrecps_f32(est0, fVec), est0);
          return est1;
      }
  
      SkNx operator + (const SkNx& o) const { return vadd_f32(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsub_f32(fVec, o.fVec); }
      SkNx operator * (const SkNx& o) const { return vmul_f32(fVec, o.fVec); }
      SkNx operator / (const SkNx& o) const {
      #if defined(SK_CPU_ARM64)
          return vdiv_f32(fVec, o.fVec);
      #else
          float32x2_t est0 = vrecpe_f32(o.fVec),
                      est1 = vmul_f32(vrecps_f32(est0, o.fVec), est0),
                      est2 = vmul_f32(vrecps_f32(est1, o.fVec), est1);
          return vmul_f32(fVec, est2);
      #endif
      }
  
      SkNx operator == (const SkNx& o) const { return vreinterpret_f32_u32(vceq_f32(fVec, o.fVec)); }
      SkNx operator  < (const SkNx& o) const { return vreinterpret_f32_u32(vclt_f32(fVec, o.fVec)); }
      SkNx operator  > (const SkNx& o) const { return vreinterpret_f32_u32(vcgt_f32(fVec, o.fVec)); }
      SkNx operator <= (const SkNx& o) const { return vreinterpret_f32_u32(vcle_f32(fVec, o.fVec)); }
      SkNx operator >= (const SkNx& o) const { return vreinterpret_f32_u32(vcge_f32(fVec, o.fVec)); }
      SkNx operator != (const SkNx& o) const {
          return vreinterpret_f32_u32(vmvn_u32(vceq_f32(fVec, o.fVec)));
      }
  
      static SkNx Min(const SkNx& l, const SkNx& r) { return vmin_f32(l.fVec, r.fVec); }
      static SkNx Max(const SkNx& l, const SkNx& r) { return vmax_f32(l.fVec, r.fVec); }
  
      SkNx rsqrt() const {
          float32x2_t est0 = vrsqrte_f32(fVec);
          return vmul_f32(vrsqrts_f32(fVec, vmul_f32(est0, est0)), est0);
      }
  
      SkNx sqrt() const {
      #if defined(SK_CPU_ARM64)
          return vsqrt_f32(fVec);
      #else
          float32x2_t est0 = vrsqrte_f32(fVec),
                      est1 = vmul_f32(vrsqrts_f32(fVec, vmul_f32(est0, est0)), est0),
                      est2 = vmul_f32(vrsqrts_f32(fVec, vmul_f32(est1, est1)), est1);
          return vmul_f32(fVec, est2);
      #endif
      }
  
      float operator[](int k) const {
          SkASSERT(0 <= k && k < 2);
          union { float32x2_t v; float fs[2]; } pun = {fVec};
          return pun.fs[k&1];
      }
  
      bool allTrue() const {
          auto v = vreinterpret_u32_f32(fVec);
          return vget_lane_u32(v,0) && vget_lane_u32(v,1);
      }
      bool anyTrue() const {
          auto v = vreinterpret_u32_f32(fVec);
          return vget_lane_u32(v,0) || vget_lane_u32(v,1);
      }
  
      float32x2_t fVec;
  };
  
  template <>
  class SkNx<4, float> {
  public:
      SkNx(float32x4_t vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(float val)           : fVec(vdupq_n_f32(val)) {}
      static SkNx Load(const void* ptr) { return vld1q_f32((const float*)ptr); }
      SkNx(float a, float b, float c, float d) { fVec = (float32x4_t) { a, b, c, d }; }
  
      void store(void* ptr) const { vst1q_f32((float*)ptr, fVec); }
      SkNx invert() const {
          float32x4_t est0 = vrecpeq_f32(fVec),
                      est1 = vmulq_f32(vrecpsq_f32(est0, fVec), est0);
          return est1;
      }
  
      SkNx operator + (const SkNx& o) const { return vaddq_f32(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsubq_f32(fVec, o.fVec); }
      SkNx operator * (const SkNx& o) const { return vmulq_f32(fVec, o.fVec); }
      SkNx operator / (const SkNx& o) const {
      #if defined(SK_CPU_ARM64)
          return vdivq_f32(fVec, o.fVec);
      #else
          float32x4_t est0 = vrecpeq_f32(o.fVec),
                      est1 = vmulq_f32(vrecpsq_f32(est0, o.fVec), est0),
                      est2 = vmulq_f32(vrecpsq_f32(est1, o.fVec), est1);
          return vmulq_f32(fVec, est2);
      #endif
      }
  
      SkNx operator==(const SkNx& o) const { return vreinterpretq_f32_u32(vceqq_f32(fVec, o.fVec)); }
      SkNx operator <(const SkNx& o) const { return vreinterpretq_f32_u32(vcltq_f32(fVec, o.fVec)); }
      SkNx operator >(const SkNx& o) const { return vreinterpretq_f32_u32(vcgtq_f32(fVec, o.fVec)); }
      SkNx operator<=(const SkNx& o) const { return vreinterpretq_f32_u32(vcleq_f32(fVec, o.fVec)); }
      SkNx operator>=(const SkNx& o) const { return vreinterpretq_f32_u32(vcgeq_f32(fVec, o.fVec)); }
      SkNx operator!=(const SkNx& o) const {
          return vreinterpretq_f32_u32(vmvnq_u32(vceqq_f32(fVec, o.fVec)));
      }
  
      static SkNx Min(const SkNx& l, const SkNx& r) { return vminq_f32(l.fVec, r.fVec); }
      static SkNx Max(const SkNx& l, const SkNx& r) { return vmaxq_f32(l.fVec, r.fVec); }
  
      SkNx abs() const { return vabsq_f32(fVec); }
      SkNx floor() const {
      #if defined(SK_CPU_ARM64)
          return vrndmq_f32(fVec);
      #else
          return armv7_vrndmq_f32(fVec);
      #endif
      }
  
  
      SkNx rsqrt() const {
          float32x4_t est0 = vrsqrteq_f32(fVec);
          return vmulq_f32(vrsqrtsq_f32(fVec, vmulq_f32(est0, est0)), est0);
      }
  
      SkNx sqrt() const {
      #if defined(SK_CPU_ARM64)
          return vsqrtq_f32(fVec);
      #else
          float32x4_t est0 = vrsqrteq_f32(fVec),
                      est1 = vmulq_f32(vrsqrtsq_f32(fVec, vmulq_f32(est0, est0)), est0),
                      est2 = vmulq_f32(vrsqrtsq_f32(fVec, vmulq_f32(est1, est1)), est1);
          return vmulq_f32(fVec, est2);
      #endif
      }
  
      float operator[](int k) const {
          SkASSERT(0 <= k && k < 4);
          union { float32x4_t v; float fs[4]; } pun = {fVec};
          return pun.fs[k&3];
      }
  
      bool allTrue() const {
          auto v = vreinterpretq_u32_f32(fVec);
          return vgetq_lane_u32(v,0) && vgetq_lane_u32(v,1)
              && vgetq_lane_u32(v,2) && vgetq_lane_u32(v,3);
      }
      bool anyTrue() const {
          auto v = vreinterpretq_u32_f32(fVec);
          return vgetq_lane_u32(v,0) || vgetq_lane_u32(v,1)
              || vgetq_lane_u32(v,2) || vgetq_lane_u32(v,3);
      }
  
      SkNx thenElse(const SkNx& t, const SkNx& e) const {
          return vbslq_f32(vreinterpretq_u32_f32(fVec), t.fVec, e.fVec);
      }
  
      float32x4_t fVec;
  };
  
  // It's possible that for our current use cases, representing this as
  // half a uint16x8_t might be better than representing it as a uint16x4_t.
  // It'd make conversion to Sk4b one step simpler.
  template <>
  class SkNx<4, uint16_t> {
  public:
      SkNx(const uint16x4_t& vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(uint16_t val) : fVec(vdup_n_u16(val)) {}
      static SkNx Load(const void* ptr) { return vld1_u16((const uint16_t*)ptr); }
  
      SkNx(uint16_t a, uint16_t b, uint16_t c, uint16_t d) {
          fVec = (uint16x4_t) { a,b,c,d };
      }
  
      void store(void* ptr) const { vst1_u16((uint16_t*)ptr, fVec); }
  
      SkNx operator + (const SkNx& o) const { return vadd_u16(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsub_u16(fVec, o.fVec); }
      SkNx operator * (const SkNx& o) const { return vmul_u16(fVec, o.fVec); }
  
      SkNx operator << (int bits) const { SHIFT16(vshl_n_u16, fVec, bits); }
      SkNx operator >> (int bits) const { SHIFT16(vshr_n_u16, fVec, bits); }
  
      static SkNx Min(const SkNx& a, const SkNx& b) { return vmin_u16(a.fVec, b.fVec); }
  
      uint16_t operator[](int k) const {
          SkASSERT(0 <= k && k < 4);
          union { uint16x4_t v; uint16_t us[4]; } pun = {fVec};
          return pun.us[k&3];
      }
  
      SkNx thenElse(const SkNx& t, const SkNx& e) const {
          return vbsl_u16(fVec, t.fVec, e.fVec);
      }
  
      uint16x4_t fVec;
  };
  
  template <>
  class SkNx<8, uint16_t> {
  public:
      SkNx(const uint16x8_t& vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(uint16_t val) : fVec(vdupq_n_u16(val)) {}
      static SkNx Load(const void* ptr) { return vld1q_u16((const uint16_t*)ptr); }
  
      SkNx(uint16_t a, uint16_t b, uint16_t c, uint16_t d,
           uint16_t e, uint16_t f, uint16_t g, uint16_t h) {
          fVec = (uint16x8_t) { a,b,c,d, e,f,g,h };
      }
  
      void store(void* ptr) const { vst1q_u16((uint16_t*)ptr, fVec); }
  
      SkNx operator + (const SkNx& o) const { return vaddq_u16(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsubq_u16(fVec, o.fVec); }
      SkNx operator * (const SkNx& o) const { return vmulq_u16(fVec, o.fVec); }
  
      SkNx operator << (int bits) const { SHIFT16(vshlq_n_u16, fVec, bits); }
      SkNx operator >> (int bits) const { SHIFT16(vshrq_n_u16, fVec, bits); }
  
      static SkNx Min(const SkNx& a, const SkNx& b) { return vminq_u16(a.fVec, b.fVec); }
  
      uint16_t operator[](int k) const {
          SkASSERT(0 <= k && k < 8);
          union { uint16x8_t v; uint16_t us[8]; } pun = {fVec};
          return pun.us[k&7];
      }
  
      SkNx thenElse(const SkNx& t, const SkNx& e) const {
          return vbslq_u16(fVec, t.fVec, e.fVec);
      }
  
      uint16x8_t fVec;
  };
  
  template <>
  class SkNx<4, uint8_t> {
  public:
      SkNx(const uint8x8_t& vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(uint8_t a, uint8_t b, uint8_t c, uint8_t d) {
          fVec = (uint8x8_t){a,b,c,d, 0,0,0,0};
      }
      static SkNx Load(const void* ptr) {
          return (uint8x8_t)vld1_dup_u32((const uint32_t*)ptr);
      }
      void store(void* ptr) const {
          return vst1_lane_u32((uint32_t*)ptr, (uint32x2_t)fVec, 0);
      }
      uint8_t operator[](int k) const {
          SkASSERT(0 <= k && k < 4);
          union { uint8x8_t v; uint8_t us[8]; } pun = {fVec};
          return pun.us[k&3];
      }
  
      // TODO as needed
  
      uint8x8_t fVec;
  };
  
  template <>
  class SkNx<16, uint8_t> {
  public:
      SkNx(const uint8x16_t& vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(uint8_t val) : fVec(vdupq_n_u8(val)) {}
      static SkNx Load(const void* ptr) { return vld1q_u8((const uint8_t*)ptr); }
  
      SkNx(uint8_t a, uint8_t b, uint8_t c, uint8_t d,
           uint8_t e, uint8_t f, uint8_t g, uint8_t h,
           uint8_t i, uint8_t j, uint8_t k, uint8_t l,
           uint8_t m, uint8_t n, uint8_t o, uint8_t p) {
          fVec = (uint8x16_t) { a,b,c,d, e,f,g,h, i,j,k,l, m,n,o,p };
      }
  
      void store(void* ptr) const { vst1q_u8((uint8_t*)ptr, fVec); }
  
      SkNx saturatedAdd(const SkNx& o) const { return vqaddq_u8(fVec, o.fVec); }
  
      SkNx operator + (const SkNx& o) const { return vaddq_u8(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsubq_u8(fVec, o.fVec); }
  
      static SkNx Min(const SkNx& a, const SkNx& b) { return vminq_u8(a.fVec, b.fVec); }
      SkNx operator < (const SkNx& o) const { return vcltq_u8(fVec, o.fVec); }
  
      uint8_t operator[](int k) const {
          SkASSERT(0 <= k && k < 16);
          union { uint8x16_t v; uint8_t us[16]; } pun = {fVec};
          return pun.us[k&15];
      }
  
      SkNx thenElse(const SkNx& t, const SkNx& e) const {
          return vbslq_u8(fVec, t.fVec, e.fVec);
      }
  
      uint8x16_t fVec;
  };
  
  template <>
  class SkNx<4, int> {
  public:
      SkNx(const int32x4_t& vec) : fVec(vec) {}
  
      SkNx() {}
      SkNx(int v) {
          fVec = vdupq_n_s32(v);
      }
      SkNx(int a, int b, int c, int d) {
          fVec = (int32x4_t){a,b,c,d};
      }
      static SkNx Load(const void* ptr) {
          return vld1q_s32((const int32_t*)ptr);
      }
      void store(void* ptr) const {
          return vst1q_s32((int32_t*)ptr, fVec);
      }
      int operator[](int k) const {
          SkASSERT(0 <= k && k < 4);
          union { int32x4_t v; int is[4]; } pun = {fVec};
          return pun.is[k&3];
      }
  
      SkNx operator + (const SkNx& o) const { return vaddq_s32(fVec, o.fVec); }
      SkNx operator - (const SkNx& o) const { return vsubq_s32(fVec, o.fVec); }
      SkNx operator * (const SkNx& o) const { return vmulq_s32(fVec, o.fVec); }
  
      SkNx operator << (int bits) const { SHIFT32(vshlq_n_s32, fVec, bits); }
      SkNx operator >> (int bits) const { SHIFT32(vshrq_n_s32, fVec, bits); }
  
      static SkNx Min(const SkNx& a, const SkNx& b) { return vminq_s32(a.fVec, b.fVec); }
      // TODO as needed
  
      int32x4_t fVec;
  };
  
  #undef SHIFT32
  #undef SHIFT16
  #undef SHIFT8
  
  template<> inline Sk4i SkNx_cast<int, float>(const Sk4f& src) {
      return vcvtq_s32_f32(src.fVec);
  
  }
  template<> inline Sk4f SkNx_cast<float, int>(const Sk4i& src) {
      return vcvtq_f32_s32(src.fVec);
  }
  
  template<> inline Sk4h SkNx_cast<uint16_t, float>(const Sk4f& src) {
      return vqmovn_u32(vcvtq_u32_f32(src.fVec));
  }
  
  template<> inline Sk4f SkNx_cast<float, uint16_t>(const Sk4h& src) {
      return vcvtq_f32_u32(vmovl_u16(src.fVec));
  }
  
  template<> inline Sk4b SkNx_cast<uint8_t, float>(const Sk4f& src) {
      uint32x4_t _32 = vcvtq_u32_f32(src.fVec);
      uint16x4_t _16 = vqmovn_u32(_32);
      return vqmovn_u16(vcombine_u16(_16, _16));
  }
  
  template<> inline Sk4f SkNx_cast<float, uint8_t>(const Sk4b& src) {
      uint16x8_t _16 = vmovl_u8 (src.fVec) ;
      uint32x4_t _32 = vmovl_u16(vget_low_u16(_16));
      return vcvtq_f32_u32(_32);
  }
  
  template<> inline Sk16b SkNx_cast<uint8_t, float>(const Sk16f& src) {
      Sk8f ab, cd;
      SkNx_split(src, &ab, &cd);
  
      Sk4f a,b,c,d;
      SkNx_split(ab, &a, &b);
      SkNx_split(cd, &c, &d);
      return vuzpq_u8(vuzpq_u8((uint8x16_t)vcvtq_u32_f32(a.fVec),
                               (uint8x16_t)vcvtq_u32_f32(b.fVec)).val[0],
                      vuzpq_u8((uint8x16_t)vcvtq_u32_f32(c.fVec),
                               (uint8x16_t)vcvtq_u32_f32(d.fVec)).val[0]).val[0];
  }
  
  template<> inline Sk4h SkNx_cast<uint16_t, uint8_t>(const Sk4b& src) {
      return vget_low_u16(vmovl_u8(src.fVec));
  }
  
  template<> inline Sk4b SkNx_cast<uint8_t, uint16_t>(const Sk4h& src) {
      return vmovn_u16(vcombine_u16(src.fVec, src.fVec));
  }
  
  #endif//SkNx_neon_DEFINED
  