src/opts/SkXfermode_opts.h - platform/external/skia - Gitiles

 /*
  * 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 Sk4pxXfermode_DEFINED
 #define Sk4pxXfermode_DEFINED

 #include "Sk4px.h"
 #include "SkMSAN.h"
 #include "SkNx.h"
 #include "SkXfermode_proccoeff.h"

 namespace {

 // Most xfermodes can be done most efficiently 4 pixels at a time in 8 or 16-bit fixed point.
 #define XFERMODE(Xfermode) \
     struct Xfermode { Sk4px operator()(const Sk4px&, const Sk4px&) const; }; \
     inline Sk4px Xfermode::operator()(const Sk4px& d, const Sk4px& s) const

 XFERMODE(Clear) { return Sk4px::DupPMColor(0); }
 XFERMODE(Src)   { return s; }
 XFERMODE(Dst)   { return d; }
 XFERMODE(SrcIn)   { return     s.approxMulDiv255(d.alphas()      ); }
 XFERMODE(SrcOut)  { return     s.approxMulDiv255(d.alphas().inv()); }
 XFERMODE(SrcOver) { return s + d.approxMulDiv255(s.alphas().inv()); }
 XFERMODE(DstIn)   { return SrcIn  ()(s,d); }
 XFERMODE(DstOut)  { return SrcOut ()(s,d); }
 XFERMODE(DstOver) { return SrcOver()(s,d); }

 // [ S * Da + (1 - Sa) * D]
 XFERMODE(SrcATop) { return (s * d.alphas() + d * s.alphas().inv()).div255(); }
 XFERMODE(DstATop) { return SrcATop()(s,d); }
 //[ S * (1 - Da) + (1 - Sa) * D ]
 XFERMODE(Xor) { return (s * d.alphas().inv() + d * s.alphas().inv()).div255(); }
 // [S + D ]
 XFERMODE(Plus) { return s.saturatedAdd(d); }
 // [S * D ]
 XFERMODE(Modulate) { return s.approxMulDiv255(d); }
 // [S + D - S * D]
 XFERMODE(Screen) {
     // Doing the math as S + (1-S)*D or S + (D - S*D) means the add and subtract can be done
     // in 8-bit space without overflow.  S + (1-S)*D is a touch faster because inv() is cheap.
     return s + d.approxMulDiv255(s.inv());
 }
 XFERMODE(Multiply) { return (s * d.alphas().inv() + d * s.alphas().inv() + s*d).div255(); }
 // [ Sa + Da - Sa*Da, Sc + Dc - 2*min(Sc*Da, Dc*Sa) ]  (And notice Sa*Da == min(Sa*Da, Da*Sa).)
 XFERMODE(Difference) {
     auto m = Sk4px::Wide::Min(s * d.alphas(), d * s.alphas()).div255();
     // There's no chance of underflow, and if we subtract m before adding s+d, no overflow.
     return (s - m) + (d - m.zeroAlphas());
 }
 // [ Sa + Da - Sa*Da, Sc + Dc - 2*Sc*Dc ]
 XFERMODE(Exclusion) {
     auto p = s.approxMulDiv255(d);
     // There's no chance of underflow, and if we subtract p before adding src+dst, no overflow.
     return (s - p) + (d - p.zeroAlphas());
 }

 // We take care to use exact math for these next few modes where alphas
 // and colors are calculated using significantly different math.  We need
 // to preserve premul invariants, and exact math makes this easier.
 //
 // TODO: Some of these implementations might be able to be sped up a bit
 // while maintaining exact math, but let's follow up with that.

 XFERMODE(HardLight) {
     auto sa = s.alphas(),
          da = d.alphas();

     auto srcover = s + (d * sa.inv()).div255();

     auto isLite = ((sa-s) < s).widenLoHi();

     auto lite = sa*da - ((da-d)*(sa-s) << 1),
          dark = s*d << 1,
          both = s*da.inv() + d*sa.inv();

     auto alphas = srcover;
     auto colors = (both + isLite.thenElse(lite, dark)).div255();
     return alphas.zeroColors() + colors.zeroAlphas();
 }
 XFERMODE(Overlay) { return HardLight()(s,d); }

 XFERMODE(Darken) {
     auto sa = s.alphas(),
          da = d.alphas();

     auto sda = (s*da).div255(),
          dsa = (d*sa).div255();

     auto srcover = s + (d * sa.inv()).div255(),
          dstover = d + (s * da.inv()).div255();
     auto alphas = srcover,
          colors = (sda < dsa).thenElse(srcover, dstover);
     return alphas.zeroColors() + colors.zeroAlphas();
 }
 XFERMODE(Lighten) {
     auto sa = s.alphas(),
          da = d.alphas();

     auto sda = (s*da).div255(),
          dsa = (d*sa).div255();

     auto srcover = s + (d * sa.inv()).div255(),
          dstover = d + (s * da.inv()).div255();
     auto alphas = srcover,
          colors = (dsa < sda).thenElse(srcover, dstover);
     return alphas.zeroColors() + colors.zeroAlphas();
 }
 #undef XFERMODE

 // Some xfermodes use math like divide or sqrt that's best done in floats 1 pixel at a time.
 #define XFERMODE(Xfermode) \
     struct Xfermode { Sk4f operator()(const Sk4f&, const Sk4f&) const; }; \
     inline Sk4f Xfermode::operator()(const Sk4f& d, const Sk4f& s) const

 static inline Sk4f a_rgb(const Sk4f& a, const Sk4f& rgb) {
     static_assert(SK_A32_SHIFT == 24, "");
     return a * Sk4f(0,0,0,1) + rgb * Sk4f(1,1,1,0);
 }
 static inline Sk4f alphas(const Sk4f& f) {
     return f[SK_A32_SHIFT/8];
 }

 XFERMODE(ColorDodge) {
     auto sa = alphas(s),
          da = alphas(d),
          isa = Sk4f(1)-sa,
          ida = Sk4f(1)-da;

     auto srcover = s + d*isa,
          dstover = d + s*ida,
          otherwise = sa * Sk4f::Min(da, (d*sa)*(sa-s).invert()) + s*ida + d*isa;

     // Order matters here, preferring d==0 over s==sa.
     auto colors = (d == Sk4f(0)).thenElse(dstover,
                   (s ==      sa).thenElse(srcover,
                                           otherwise));
     return a_rgb(srcover, colors);
 }
 XFERMODE(ColorBurn) {
     auto sa = alphas(s),
          da = alphas(d),
          isa = Sk4f(1)-sa,
          ida = Sk4f(1)-da;

     auto srcover = s + d*isa,
          dstover = d + s*ida,
          otherwise = sa*(da-Sk4f::Min(da, (da-d)*sa*s.invert())) + s*ida + d*isa;

     // Order matters here, preferring d==da over s==0.
     auto colors = (d ==      da).thenElse(dstover,
                   (s == Sk4f(0)).thenElse(srcover,
                                           otherwise));
     return a_rgb(srcover, colors);
 }
 XFERMODE(SoftLight) {
     auto sa = alphas(s),
          da = alphas(d),
          isa = Sk4f(1)-sa,
          ida = Sk4f(1)-da;

     // Some common terms.
     auto m  = (da > Sk4f(0)).thenElse(d / da, Sk4f(0)),
          s2 = Sk4f(2)*s,
          m4 = Sk4f(4)*m;

     // The logic forks three ways:
     //    1. dark src?
     //    2. light src, dark dst?
     //    3. light src, light dst?
     auto darkSrc = d*(sa + (s2 - sa)*(Sk4f(1) - m)),        // Used in case 1.
          darkDst = (m4*m4 + m4)*(m - Sk4f(1)) + Sk4f(7)*m,  // Used in case 2.
          liteDst = m.sqrt() - m,                            // Used in case 3.
          liteSrc = d*sa + da*(s2-sa)*(Sk4f(4)*d <= da).thenElse(darkDst, liteDst); // Case 2 or 3?

     auto alpha  = s + d*isa;
     auto colors = s*ida + d*isa + (s2 <= sa).thenElse(darkSrc, liteSrc);           // Case 1 or 2/3?

     return a_rgb(alpha, colors);
 }
 #undef XFERMODE

 // A reasonable fallback mode for doing AA is to simply apply the transfermode first,
 // then linearly interpolate the AA.
 template <typename Xfermode>
 static Sk4px xfer_aa(const Sk4px& d, const Sk4px& s, const Sk4px& aa) {
     Sk4px bw = Xfermode()(d, s);
     return (bw * aa + d * aa.inv()).div255();
 }

 // For some transfermodes we specialize AA, either for correctness or performance.
 #define XFERMODE_AA(Xfermode) \
     template <> Sk4px xfer_aa<Xfermode>(const Sk4px& d, const Sk4px& s, const Sk4px& aa)

 // Plus' clamp needs to happen after AA.  skia:3852
 XFERMODE_AA(Plus) {  // [ clamp( (1-AA)D + (AA)(S+D) ) == clamp(D + AA*S) ]
     return d.saturatedAdd(s.approxMulDiv255(aa));
 }

 #undef XFERMODE_AA

 // Src and Clear modes are safe to use with unitialized dst buffers,
 // even if the implementation branches based on bytes from dst (e.g. asserts in Debug mode).
 // For those modes, just lie to MSAN that dst is always intialized.
 template <typename Xfermode> static void mark_dst_initialized_if_safe(void*, void*) {}
 template <> void mark_dst_initialized_if_safe<Src>(void* dst, void* end) {
     sk_msan_mark_initialized(dst, end, "Src doesn't read dst.");
 }
 template <> void mark_dst_initialized_if_safe<Clear>(void* dst, void* end) {
     sk_msan_mark_initialized(dst, end, "Clear doesn't read dst.");
 }

 template <typename Xfermode>
 class Sk4pxXfermode : public SkProcCoeffXfermode {
 public:
     Sk4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
         : INHERITED(rec, mode) {}

     void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
         mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
         if (nullptr == aa) {
             Sk4px::MapDstSrc(n, dst, src, Xfermode());
         } else {
             Sk4px::MapDstSrcAlpha(n, dst, src, aa, xfer_aa<Xfermode>);
         }
     }

     void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
         mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
         SkPMColor dst32[4];
         while (n >= 4) {
             dst32[0] = SkPixel16ToPixel32(dst[0]);
             dst32[1] = SkPixel16ToPixel32(dst[1]);
             dst32[2] = SkPixel16ToPixel32(dst[2]);
             dst32[3] = SkPixel16ToPixel32(dst[3]);

             this->xfer32(dst32, src, 4, aa);

             dst[0] = SkPixel32ToPixel16(dst32[0]);
             dst[1] = SkPixel32ToPixel16(dst32[1]);
             dst[2] = SkPixel32ToPixel16(dst32[2]);
             dst[3] = SkPixel32ToPixel16(dst32[3]);

             dst += 4;
             src += 4;
             aa  += aa ? 4 : 0;
             n -= 4;
         }
         while (n) {
             SkPMColor dst32 = SkPixel16ToPixel32(*dst);
             this->xfer32(&dst32, src, 1, aa);
             *dst = SkPixel32ToPixel16(dst32);

             dst += 1;
             src += 1;
             aa  += aa ? 1 : 0;
             n   -= 1;
         }
     }

 private:
     typedef SkProcCoeffXfermode INHERITED;
 };

 template <typename Xfermode>
 class Sk4fXfermode : public SkProcCoeffXfermode {
 public:
     Sk4fXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
         : INHERITED(rec, mode) {}

     void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
         for (int i = 0; i < n; i++) {
             dst[i] = Xfer32_1(dst[i], src[i], aa ? aa+i : nullptr);
         }
     }

     void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
         for (int i = 0; i < n; i++) {
             SkPMColor dst32 = SkPixel16ToPixel32(dst[i]);
             dst32 = Xfer32_1(dst32, src[i], aa ? aa+i : nullptr);
             dst[i] = SkPixel32ToPixel16(dst32);
         }
     }

 private:
     static SkPMColor Xfer32_1(SkPMColor dst, const SkPMColor src, const SkAlpha* aa) {
         Sk4f d = Load(dst),
              s = Load(src),
              b = Xfermode()(d, s);
         if (aa) {
             Sk4f a = Sk4f(*aa) * Sk4f(1.0f/255);
             b = b*a + d*(Sk4f(1)-a);
         }
         return Round(b);
     }

     static Sk4f Load(SkPMColor c) {
         return SkNx_cast<float>(Sk4b::Load(&c)) * Sk4f(1.0f/255);
     }

     static SkPMColor Round(const Sk4f& f) {
         SkPMColor c;
         SkNx_cast<uint8_t>(f * Sk4f(255) + Sk4f(0.5f)).store(&c);
         return c;
     }

     typedef SkProcCoeffXfermode INHERITED;
 };

 } // namespace

 namespace SK_OPTS_NS {

 static SkXfermode* create_xfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
     switch (mode) {
 #define CASE(Xfermode) \
     case SkXfermode::k##Xfermode##_Mode: return new Sk4pxXfermode<Xfermode>(rec, mode)
         CASE(Clear);
         CASE(Src);
         CASE(Dst);
         CASE(SrcOver);
         CASE(DstOver);
         CASE(SrcIn);
         CASE(DstIn);
         CASE(SrcOut);
         CASE(DstOut);
         CASE(SrcATop);
         CASE(DstATop);
         CASE(Xor);
         CASE(Plus);
         CASE(Modulate);
         CASE(Screen);
         CASE(Multiply);
         CASE(Difference);
         CASE(Exclusion);
         CASE(HardLight);
         CASE(Overlay);
         CASE(Darken);
         CASE(Lighten);
     #undef CASE

 #define CASE(Xfermode) \
     case SkXfermode::k##Xfermode##_Mode: return new Sk4fXfermode<Xfermode>(rec, mode)
         CASE(ColorDodge);
         CASE(ColorBurn);
         CASE(SoftLight);
     #undef CASE

         default: break;
     }
     return nullptr;
 }

 } // namespace SK_OPTS_NS

 #endif//Sk4pxXfermode_DEFINED
	/*
	* 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 Sk4pxXfermode_DEFINED
	#define Sk4pxXfermode_DEFINED

	#include "Sk4px.h"
	#include "SkMSAN.h"
	#include "SkNx.h"
	#include "SkXfermode_proccoeff.h"

	namespace {

	// Most xfermodes can be done most efficiently 4 pixels at a time in 8 or 16-bit fixed point.
	#define XFERMODE(Xfermode) \
	struct Xfermode { Sk4px operator()(const Sk4px&, const Sk4px&) const; }; \
	inline Sk4px Xfermode::operator()(const Sk4px& d, const Sk4px& s) const

	XFERMODE(Clear) { return Sk4px::DupPMColor(0); }
	XFERMODE(Src) { return s; }
	XFERMODE(Dst) { return d; }
	XFERMODE(SrcIn) { return s.approxMulDiv255(d.alphas() ); }
	XFERMODE(SrcOut) { return s.approxMulDiv255(d.alphas().inv()); }
	XFERMODE(SrcOver) { return s + d.approxMulDiv255(s.alphas().inv()); }
	XFERMODE(DstIn) { return SrcIn ()(s,d); }
	XFERMODE(DstOut) { return SrcOut ()(s,d); }
	XFERMODE(DstOver) { return SrcOver()(s,d); }

	// [ S * Da + (1 - Sa) * D]
	XFERMODE(SrcATop) { return (s * d.alphas() + d * s.alphas().inv()).div255(); }
	XFERMODE(DstATop) { return SrcATop()(s,d); }
	//[ S * (1 - Da) + (1 - Sa) * D ]
	XFERMODE(Xor) { return (s * d.alphas().inv() + d * s.alphas().inv()).div255(); }
	// [S + D ]
	XFERMODE(Plus) { return s.saturatedAdd(d); }
	// [S * D ]
	XFERMODE(Modulate) { return s.approxMulDiv255(d); }
	// [S + D - S * D]
	XFERMODE(Screen) {
	// Doing the math as S + (1-S)D or S + (D - SD) means the add and subtract can be done
	// in 8-bit space without overflow. S + (1-S)*D is a touch faster because inv() is cheap.
	return s + d.approxMulDiv255(s.inv());
	}
	XFERMODE(Multiply) { return (s * d.alphas().inv() + d * s.alphas().inv() + s*d).div255(); }
	// [ Sa + Da - SaDa, Sc + Dc - 2min(ScDa, DcSa) ] (And notice SaDa == min(SaDa, Da*Sa).)
	XFERMODE(Difference) {
	auto m = Sk4px::Wide::Min(s * d.alphas(), d * s.alphas()).div255();
	// There's no chance of underflow, and if we subtract m before adding s+d, no overflow.
	return (s - m) + (d - m.zeroAlphas());
	}
	// [ Sa + Da - SaDa, Sc + Dc - 2Sc*Dc ]
	XFERMODE(Exclusion) {
	auto p = s.approxMulDiv255(d);
	// There's no chance of underflow, and if we subtract p before adding src+dst, no overflow.
	return (s - p) + (d - p.zeroAlphas());
	}

	// We take care to use exact math for these next few modes where alphas
	// and colors are calculated using significantly different math. We need
	// to preserve premul invariants, and exact math makes this easier.
	//
	// TODO: Some of these implementations might be able to be sped up a bit
	// while maintaining exact math, but let's follow up with that.

	XFERMODE(HardLight) {
	auto sa = s.alphas(),
	da = d.alphas();

	auto srcover = s + (d * sa.inv()).div255();

	auto isLite = ((sa-s) < s).widenLoHi();

	auto lite = sada - ((da-d)(sa-s) << 1),
	dark = s*d << 1,
	both = sda.inv() + dsa.inv();

	auto alphas = srcover;
	auto colors = (both + isLite.thenElse(lite, dark)).div255();
	return alphas.zeroColors() + colors.zeroAlphas();
	}
	XFERMODE(Overlay) { return HardLight()(s,d); }

	XFERMODE(Darken) {
	auto sa = s.alphas(),
	da = d.alphas();

	auto sda = (s*da).div255(),
	dsa = (d*sa).div255();

	auto srcover = s + (d * sa.inv()).div255(),
	dstover = d + (s * da.inv()).div255();
	auto alphas = srcover,
	colors = (sda < dsa).thenElse(srcover, dstover);
	return alphas.zeroColors() + colors.zeroAlphas();
	}
	XFERMODE(Lighten) {
	auto sa = s.alphas(),
	da = d.alphas();

	auto sda = (s*da).div255(),
	dsa = (d*sa).div255();

	auto srcover = s + (d * sa.inv()).div255(),
	dstover = d + (s * da.inv()).div255();
	auto alphas = srcover,
	colors = (dsa < sda).thenElse(srcover, dstover);
	return alphas.zeroColors() + colors.zeroAlphas();
	}
	#undef XFERMODE

	// Some xfermodes use math like divide or sqrt that's best done in floats 1 pixel at a time.
	#define XFERMODE(Xfermode) \
	struct Xfermode { Sk4f operator()(const Sk4f&, const Sk4f&) const; }; \
	inline Sk4f Xfermode::operator()(const Sk4f& d, const Sk4f& s) const

	static inline Sk4f a_rgb(const Sk4f& a, const Sk4f& rgb) {
	static_assert(SK_A32_SHIFT == 24, "");
	return a * Sk4f(0,0,0,1) + rgb * Sk4f(1,1,1,0);
	}
	static inline Sk4f alphas(const Sk4f& f) {
	return f[SK_A32_SHIFT/8];
	}

	XFERMODE(ColorDodge) {
	auto sa = alphas(s),
	da = alphas(d),
	isa = Sk4f(1)-sa,
	ida = Sk4f(1)-da;

	auto srcover = s + d*isa,
	dstover = d + s*ida,
	otherwise = sa * Sk4f::Min(da, (dsa)(sa-s).invert()) + sida + disa;

	// Order matters here, preferring d==0 over s==sa.
	auto colors = (d == Sk4f(0)).thenElse(dstover,
	(s == sa).thenElse(srcover,
	otherwise));
	return a_rgb(srcover, colors);
	}
	XFERMODE(ColorBurn) {
	auto sa = alphas(s),
	da = alphas(d),
	isa = Sk4f(1)-sa,
	ida = Sk4f(1)-da;

	auto srcover = s + d*isa,
	dstover = d + s*ida,
	otherwise = sa(da-Sk4f::Min(da, (da-d)sas.invert())) + sida + d*isa;

	// Order matters here, preferring d==da over s==0.
	auto colors = (d == da).thenElse(dstover,
	(s == Sk4f(0)).thenElse(srcover,
	otherwise));
	return a_rgb(srcover, colors);
	}
	XFERMODE(SoftLight) {
	auto sa = alphas(s),
	da = alphas(d),
	isa = Sk4f(1)-sa,
	ida = Sk4f(1)-da;

	// Some common terms.
	auto m = (da > Sk4f(0)).thenElse(d / da, Sk4f(0)),
	s2 = Sk4f(2)*s,
	m4 = Sk4f(4)*m;

	// The logic forks three ways:
	// 1. dark src?
	// 2. light src, dark dst?
	// 3. light src, light dst?
	auto darkSrc = d(sa + (s2 - sa)(Sk4f(1) - m)), // Used in case 1.
	darkDst = (m4m4 + m4)(m - Sk4f(1)) + Sk4f(7)*m, // Used in case 2.
	liteDst = m.sqrt() - m, // Used in case 3.
	liteSrc = dsa + da(s2-sa)(Sk4f(4)d <= da).thenElse(darkDst, liteDst); // Case 2 or 3?

	auto alpha = s + d*isa;
	auto colors = sida + disa + (s2 <= sa).thenElse(darkSrc, liteSrc); // Case 1 or 2/3?

	return a_rgb(alpha, colors);
	}
	#undef XFERMODE

	// A reasonable fallback mode for doing AA is to simply apply the transfermode first,
	// then linearly interpolate the AA.
	template <typename Xfermode>
	static Sk4px xfer_aa(const Sk4px& d, const Sk4px& s, const Sk4px& aa) {
	Sk4px bw = Xfermode()(d, s);
	return (bw * aa + d * aa.inv()).div255();
	}

	// For some transfermodes we specialize AA, either for correctness or performance.
	#define XFERMODE_AA(Xfermode) \
	template <> Sk4px xfer_aa<Xfermode>(const Sk4px& d, const Sk4px& s, const Sk4px& aa)

	// Plus' clamp needs to happen after AA. skia:3852
	XFERMODE_AA(Plus) { // [ clamp( (1-AA)D + (AA)(S+D) ) == clamp(D + AA*S) ]
	return d.saturatedAdd(s.approxMulDiv255(aa));
	}

	#undef XFERMODE_AA

	// Src and Clear modes are safe to use with unitialized dst buffers,
	// even if the implementation branches based on bytes from dst (e.g. asserts in Debug mode).
	// For those modes, just lie to MSAN that dst is always intialized.
	template <typename Xfermode> static void mark_dst_initialized_if_safe(void, void) {}
	template <> void mark_dst_initialized_if_safe<Src>(void* dst, void* end) {
	sk_msan_mark_initialized(dst, end, "Src doesn't read dst.");
	}
	template <> void mark_dst_initialized_if_safe<Clear>(void* dst, void* end) {
	sk_msan_mark_initialized(dst, end, "Clear doesn't read dst.");
	}

	template <typename Xfermode>
	class Sk4pxXfermode : public SkProcCoeffXfermode {
	public:
	Sk4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
	: INHERITED(rec, mode) {}

	void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
	mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
	if (nullptr == aa) {
	Sk4px::MapDstSrc(n, dst, src, Xfermode());
	} else {
	Sk4px::MapDstSrcAlpha(n, dst, src, aa, xfer_aa<Xfermode>);
	}
	}

	void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
	mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
	SkPMColor dst32[4];
	while (n >= 4) {
	dst32[0] = SkPixel16ToPixel32(dst[0]);
	dst32[1] = SkPixel16ToPixel32(dst[1]);
	dst32[2] = SkPixel16ToPixel32(dst[2]);
	dst32[3] = SkPixel16ToPixel32(dst[3]);

	this->xfer32(dst32, src, 4, aa);

	dst[0] = SkPixel32ToPixel16(dst32[0]);
	dst[1] = SkPixel32ToPixel16(dst32[1]);
	dst[2] = SkPixel32ToPixel16(dst32[2]);
	dst[3] = SkPixel32ToPixel16(dst32[3]);

	dst += 4;
	src += 4;
	aa += aa ? 4 : 0;
	n -= 4;
	}
	while (n) {
	SkPMColor dst32 = SkPixel16ToPixel32(*dst);
	this->xfer32(&dst32, src, 1, aa);
	*dst = SkPixel32ToPixel16(dst32);

	dst += 1;
	src += 1;
	aa += aa ? 1 : 0;
	n -= 1;
	}
	}

	private:
	typedef SkProcCoeffXfermode INHERITED;
	};

	template <typename Xfermode>
	class Sk4fXfermode : public SkProcCoeffXfermode {
	public:
	Sk4fXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
	: INHERITED(rec, mode) {}

	void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
	for (int i = 0; i < n; i++) {
	dst[i] = Xfer32_1(dst[i], src[i], aa ? aa+i : nullptr);
	}
	}

	void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
	for (int i = 0; i < n; i++) {
	SkPMColor dst32 = SkPixel16ToPixel32(dst[i]);
	dst32 = Xfer32_1(dst32, src[i], aa ? aa+i : nullptr);
	dst[i] = SkPixel32ToPixel16(dst32);
	}
	}

	private:
	static SkPMColor Xfer32_1(SkPMColor dst, const SkPMColor src, const SkAlpha* aa) {
	Sk4f d = Load(dst),
	s = Load(src),
	b = Xfermode()(d, s);
	if (aa) {
	Sk4f a = Sk4f(aa) Sk4f(1.0f/255);
	b = ba + d(Sk4f(1)-a);
	}
	return Round(b);
	}

	static Sk4f Load(SkPMColor c) {
	return SkNx_cast<float>(Sk4b::Load(&c)) * Sk4f(1.0f/255);
	}

	static SkPMColor Round(const Sk4f& f) {
	SkPMColor c;
	SkNx_cast<uint8_t>(f * Sk4f(255) + Sk4f(0.5f)).store(&c);
	return c;
	}

	typedef SkProcCoeffXfermode INHERITED;
	};

	} // namespace

	namespace SK_OPTS_NS {

	static SkXfermode* create_xfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
	switch (mode) {
	#define CASE(Xfermode) \
	case SkXfermode::k##Xfermode##_Mode: return new Sk4pxXfermode<Xfermode>(rec, mode)
	CASE(Clear);
	CASE(Src);
	CASE(Dst);
	CASE(SrcOver);
	CASE(DstOver);
	CASE(SrcIn);
	CASE(DstIn);
	CASE(SrcOut);
	CASE(DstOut);
	CASE(SrcATop);
	CASE(DstATop);
	CASE(Xor);
	CASE(Plus);
	CASE(Modulate);
	CASE(Screen);
	CASE(Multiply);
	CASE(Difference);
	CASE(Exclusion);
	CASE(HardLight);
	CASE(Overlay);
	CASE(Darken);
	CASE(Lighten);
	#undef CASE

	#define CASE(Xfermode) \
	case SkXfermode::k##Xfermode##_Mode: return new Sk4fXfermode<Xfermode>(rec, mode)
	CASE(ColorDodge);
	CASE(ColorBurn);
	CASE(SoftLight);
	#undef CASE

	default: break;
	}
	return nullptr;
	}

	} // namespace SK_OPTS_NS

	#endif//Sk4pxXfermode_DEFINED