src/opts/SkBlitRow_opts.h - skia - Git at Google

 /*
  * 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 SkBlitRow_opts_DEFINED
 #define SkBlitRow_opts_DEFINED

 #include "Sk4px.h"
 #include "SkColorData.h"
 #include "SkMSAN.h"

 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     #include "SkColor_opts_SSE2.h"
     #include <immintrin.h>
 #endif

 namespace SK_OPTS_NS {

 // Color32 uses the blend_256_round_alt algorithm from tests/BlendTest.cpp.
 // It's not quite perfect, but it's never wrong in the interesting edge cases,
 // and it's quite a bit faster than blend_perfect.
 //
 // blend_256_round_alt is our currently blessed algorithm.  Please use it or an analogous one.
 static inline
 void blit_row_color32(SkPMColor* dst, const SkPMColor* src, int count, SkPMColor color) {
     unsigned invA = 255 - SkGetPackedA32(color);
     invA += invA >> 7;
     SkASSERT(invA < 256);  // We've should have already handled alpha == 0 externally.

     Sk16h colorHighAndRound = Sk4px::DupPMColor(color).widenHi() + Sk16h(128);
     Sk16b invA_16x(invA);

     Sk4px::MapSrc(count, dst, src, [&](const Sk4px& src4) -> Sk4px {
         return (src4 * invA_16x).addNarrowHi(colorHighAndRound);
     });
 }

 #if defined(SK_ARM_HAS_NEON)

 // Return a uint8x8_t value, r, computed as r[i] = SkMulDiv255Round(x[i], y[i]), where r[i], x[i],
 // y[i] are the i-th lanes of the corresponding NEON vectors.
 static inline uint8x8_t SkMulDiv255Round_neon8(uint8x8_t x, uint8x8_t y) {
     uint16x8_t prod = vmull_u8(x, y);
     return vraddhn_u16(prod, vrshrq_n_u16(prod, 8));
 }

 // The implementations of SkPMSrcOver below perform alpha blending consistently with
 // SkMulDiv255Round. They compute the color components (numbers in the interval [0, 255]) as:
 //
 //   result_i = src_i + rint(g(src_alpha, dst_i))
 //
 // where g(x, y) = ((255.0 - x) * y) / 255.0 and rint rounds to the nearest integer.

 // In this variant of SkPMSrcOver each NEON register, dst.val[i], src.val[i], contains the value
 // of the same color component for 8 consecutive pixels. The result of this function follows the
 // same convention.
 static inline uint8x8x4_t SkPMSrcOver_neon8(uint8x8x4_t dst, uint8x8x4_t src) {
     uint8x8_t nalphas = vmvn_u8(src.val[3]);
     uint8x8x4_t result;
     result.val[0] = vadd_u8(src.val[0], SkMulDiv255Round_neon8(nalphas,  dst.val[0]));
     result.val[1] = vadd_u8(src.val[1], SkMulDiv255Round_neon8(nalphas,  dst.val[1]));
     result.val[2] = vadd_u8(src.val[2], SkMulDiv255Round_neon8(nalphas,  dst.val[2]));
     result.val[3] = vadd_u8(src.val[3], SkMulDiv255Round_neon8(nalphas,  dst.val[3]));
     return result;
 }

 // In this variant of SkPMSrcOver dst and src contain the color components of two consecutive
 // pixels. The return value follows the same convention.
 static inline uint8x8_t SkPMSrcOver_neon2(uint8x8_t dst, uint8x8_t src) {
     const uint8x8_t alpha_indices = vcreate_u8(0x0707070703030303);
     uint8x8_t nalphas = vmvn_u8(vtbl1_u8(src, alpha_indices));
     return vadd_u8(src, SkMulDiv255Round_neon8(nalphas, dst));
 }

 #endif

 /*not static*/ inline
 void blit_row_s32a_opaque(SkPMColor* dst, const SkPMColor* src, int len, U8CPU alpha) {
     SkASSERT(alpha == 0xFF);
     sk_msan_assert_initialized(src, src+len);

 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
     while (len >= 16) {
         // Load 16 source pixels.
         auto s0 = _mm_loadu_si128((const __m128i*)(src) + 0),
              s1 = _mm_loadu_si128((const __m128i*)(src) + 1),
              s2 = _mm_loadu_si128((const __m128i*)(src) + 2),
              s3 = _mm_loadu_si128((const __m128i*)(src) + 3);

         const auto alphaMask = _mm_set1_epi32(0xFF000000);

         auto ORed = _mm_or_si128(s3, _mm_or_si128(s2, _mm_or_si128(s1, s0)));
         if (_mm_testz_si128(ORed, alphaMask)) {
             // All 16 source pixels are transparent.  Nothing to do.
             src += 16;
             dst += 16;
             len -= 16;
             continue;
         }

         auto d0 = (__m128i*)(dst) + 0,
              d1 = (__m128i*)(dst) + 1,
              d2 = (__m128i*)(dst) + 2,
              d3 = (__m128i*)(dst) + 3;

         auto ANDed = _mm_and_si128(s3, _mm_and_si128(s2, _mm_and_si128(s1, s0)));
         if (_mm_testc_si128(ANDed, alphaMask)) {
             // All 16 source pixels are opaque.  SrcOver becomes Src.
             _mm_storeu_si128(d0, s0);
             _mm_storeu_si128(d1, s1);
             _mm_storeu_si128(d2, s2);
             _mm_storeu_si128(d3, s3);
             src += 16;
             dst += 16;
             len -= 16;
             continue;
         }

         // TODO: This math is wrong.
         // Do SrcOver.
         _mm_storeu_si128(d0, SkPMSrcOver_SSE2(s0, _mm_loadu_si128(d0)));
         _mm_storeu_si128(d1, SkPMSrcOver_SSE2(s1, _mm_loadu_si128(d1)));
         _mm_storeu_si128(d2, SkPMSrcOver_SSE2(s2, _mm_loadu_si128(d2)));
         _mm_storeu_si128(d3, SkPMSrcOver_SSE2(s3, _mm_loadu_si128(d3)));
         src += 16;
         dst += 16;
         len -= 16;
     }

 #elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     while (len >= 16) {
         // Load 16 source pixels.
         auto s0 = _mm_loadu_si128((const __m128i*)(src) + 0),
              s1 = _mm_loadu_si128((const __m128i*)(src) + 1),
              s2 = _mm_loadu_si128((const __m128i*)(src) + 2),
              s3 = _mm_loadu_si128((const __m128i*)(src) + 3);

         const auto alphaMask = _mm_set1_epi32(0xFF000000);

         auto ORed = _mm_or_si128(s3, _mm_or_si128(s2, _mm_or_si128(s1, s0)));
         if (0xffff == _mm_movemask_epi8(_mm_cmpeq_epi8(_mm_and_si128(ORed, alphaMask),
                                                        _mm_setzero_si128()))) {
             // All 16 source pixels are transparent.  Nothing to do.
             src += 16;
             dst += 16;
             len -= 16;
             continue;
         }

         auto d0 = (__m128i*)(dst) + 0,
              d1 = (__m128i*)(dst) + 1,
              d2 = (__m128i*)(dst) + 2,
              d3 = (__m128i*)(dst) + 3;

         auto ANDed = _mm_and_si128(s3, _mm_and_si128(s2, _mm_and_si128(s1, s0)));
         if (0xffff == _mm_movemask_epi8(_mm_cmpeq_epi8(_mm_and_si128(ANDed, alphaMask),
                                                        alphaMask))) {
             // All 16 source pixels are opaque.  SrcOver becomes Src.
             _mm_storeu_si128(d0, s0);
             _mm_storeu_si128(d1, s1);
             _mm_storeu_si128(d2, s2);
             _mm_storeu_si128(d3, s3);
             src += 16;
             dst += 16;
             len -= 16;
             continue;
         }

         // TODO: This math is wrong.
         // Do SrcOver.
         _mm_storeu_si128(d0, SkPMSrcOver_SSE2(s0, _mm_loadu_si128(d0)));
         _mm_storeu_si128(d1, SkPMSrcOver_SSE2(s1, _mm_loadu_si128(d1)));
         _mm_storeu_si128(d2, SkPMSrcOver_SSE2(s2, _mm_loadu_si128(d2)));
         _mm_storeu_si128(d3, SkPMSrcOver_SSE2(s3, _mm_loadu_si128(d3)));

         src += 16;
         dst += 16;
         len -= 16;
     }

 #elif defined(SK_ARM_HAS_NEON)
     // Do 8-pixels at a time. A 16-pixels at a time version of this code was also tested, but it
     // underperformed on some of the platforms under test for inputs with frequent transitions of
     // alpha (corresponding to changes of the conditions [~]alpha_u64 == 0 below). It may be worth
     // revisiting the situation in the future.
     while (len >= 8) {
         // Load 8 pixels in 4 NEON registers. src_col.val[i] will contain the same color component
         // for 8 consecutive pixels (e.g. src_col.val[3] will contain all alpha components of 8
         // pixels).
         uint8x8x4_t src_col = vld4_u8(reinterpret_cast<const uint8_t*>(src));
         src += 8;
         len -= 8;

         // We now detect 2 special cases: the first occurs when all alphas are zero (the 8 pixels
         // are all transparent), the second when all alphas are fully set (they are all opaque).
         uint8x8_t alphas = src_col.val[3];
         uint64_t alphas_u64 = vget_lane_u64(vreinterpret_u64_u8(alphas), 0);
         if (alphas_u64 == 0) {
             // All pixels transparent.
             dst += 8;
             continue;
         }

         if (~alphas_u64 == 0) {
             // All pixels opaque.
             vst4_u8(reinterpret_cast<uint8_t*>(dst), src_col);
             dst += 8;
             continue;
         }

         uint8x8x4_t dst_col = vld4_u8(reinterpret_cast<uint8_t*>(dst));
         vst4_u8(reinterpret_cast<uint8_t*>(dst), SkPMSrcOver_neon8(dst_col, src_col));
         dst += 8;
     }

     // Deal with leftover pixels.
     for (; len >= 2; len -= 2, src += 2, dst += 2) {
         uint8x8_t src2 = vld1_u8(reinterpret_cast<const uint8_t*>(src));
         uint8x8_t dst2 = vld1_u8(reinterpret_cast<const uint8_t*>(dst));
         vst1_u8(reinterpret_cast<uint8_t*>(dst), SkPMSrcOver_neon2(dst2, src2));
     }

     if (len != 0) {
         uint8x8_t result = SkPMSrcOver_neon2(vcreate_u8(*dst), vcreate_u8(*src));
         vst1_lane_u32(dst, vreinterpret_u32_u8(result), 0);
     }
     return;
 #endif

     while (len-- > 0) {
         // This 0xFF000000 is not semantically necessary, but for compatibility
         // with chromium:611002 we need to keep it until we figure out where
         // the non-premultiplied src values (like 0x00FFFFFF) are coming from.
         // TODO(mtklein): sort this out and assert *src is premul here.
         if (*src & 0xFF000000) {
             *dst = (*src >= 0xFF000000) ? *src : SkPMSrcOver(*src, *dst);
         }
         src++;
         dst++;
     }
 }

 }  // SK_OPTS_NS

 #endif//SkBlitRow_opts_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 SkBlitRow_opts_DEFINED
	#define SkBlitRow_opts_DEFINED

	#include "Sk4px.h"
	#include "SkColorData.h"
	#include "SkMSAN.h"

	#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
	#include "SkColor_opts_SSE2.h"
	#include <immintrin.h>
	#endif

	namespace SK_OPTS_NS {

	// Color32 uses the blend_256_round_alt algorithm from tests/BlendTest.cpp.
	// It's not quite perfect, but it's never wrong in the interesting edge cases,
	// and it's quite a bit faster than blend_perfect.
	//
	// blend_256_round_alt is our currently blessed algorithm. Please use it or an analogous one.
	static inline
	void blit_row_color32(SkPMColor* dst, const SkPMColor* src, int count, SkPMColor color) {
	unsigned invA = 255 - SkGetPackedA32(color);
	invA += invA >> 7;
	SkASSERT(invA < 256); // We've should have already handled alpha == 0 externally.

	Sk16h colorHighAndRound = Sk4px::DupPMColor(color).widenHi() + Sk16h(128);
	Sk16b invA_16x(invA);

	Sk4px::MapSrc(count, dst, src, [&](const Sk4px& src4) -> Sk4px {
	return (src4 * invA_16x).addNarrowHi(colorHighAndRound);
	});
	}

	#if defined(SK_ARM_HAS_NEON)

	// Return a uint8x8_t value, r, computed as r[i] = SkMulDiv255Round(x[i], y[i]), where r[i], x[i],
	// y[i] are the i-th lanes of the corresponding NEON vectors.
	static inline uint8x8_t SkMulDiv255Round_neon8(uint8x8_t x, uint8x8_t y) {
	uint16x8_t prod = vmull_u8(x, y);
	return vraddhn_u16(prod, vrshrq_n_u16(prod, 8));
	}

	// The implementations of SkPMSrcOver below perform alpha blending consistently with
	// SkMulDiv255Round. They compute the color components (numbers in the interval [0, 255]) as:
	//
	// result_i = src_i + rint(g(src_alpha, dst_i))
	//
	// where g(x, y) = ((255.0 - x) * y) / 255.0 and rint rounds to the nearest integer.

	// In this variant of SkPMSrcOver each NEON register, dst.val[i], src.val[i], contains the value
	// of the same color component for 8 consecutive pixels. The result of this function follows the
	// same convention.
	static inline uint8x8x4_t SkPMSrcOver_neon8(uint8x8x4_t dst, uint8x8x4_t src) {
	uint8x8_t nalphas = vmvn_u8(src.val[3]);
	uint8x8x4_t result;
	result.val[0] = vadd_u8(src.val[0], SkMulDiv255Round_neon8(nalphas, dst.val[0]));
	result.val[1] = vadd_u8(src.val[1], SkMulDiv255Round_neon8(nalphas, dst.val[1]));
	result.val[2] = vadd_u8(src.val[2], SkMulDiv255Round_neon8(nalphas, dst.val[2]));
	result.val[3] = vadd_u8(src.val[3], SkMulDiv255Round_neon8(nalphas, dst.val[3]));
	return result;
	}

	// In this variant of SkPMSrcOver dst and src contain the color components of two consecutive
	// pixels. The return value follows the same convention.
	static inline uint8x8_t SkPMSrcOver_neon2(uint8x8_t dst, uint8x8_t src) {
	const uint8x8_t alpha_indices = vcreate_u8(0x0707070703030303);
	uint8x8_t nalphas = vmvn_u8(vtbl1_u8(src, alpha_indices));
	return vadd_u8(src, SkMulDiv255Round_neon8(nalphas, dst));
	}

	#endif

	/not static/ inline
	void blit_row_s32a_opaque(SkPMColor* dst, const SkPMColor* src, int len, U8CPU alpha) {
	SkASSERT(alpha == 0xFF);
	sk_msan_assert_initialized(src, src+len);

	#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
	while (len >= 16) {
	// Load 16 source pixels.
	auto s0 = _mm_loadu_si128((const __m128i*)(src) + 0),
	s1 = _mm_loadu_si128((const __m128i*)(src) + 1),
	s2 = _mm_loadu_si128((const __m128i*)(src) + 2),
	s3 = _mm_loadu_si128((const __m128i*)(src) + 3);

	const auto alphaMask = _mm_set1_epi32(0xFF000000);

	auto ORed = _mm_or_si128(s3, _mm_or_si128(s2, _mm_or_si128(s1, s0)));
	if (_mm_testz_si128(ORed, alphaMask)) {
	// All 16 source pixels are transparent. Nothing to do.
	src += 16;
	dst += 16;
	len -= 16;
	continue;
	}

	auto d0 = (__m128i*)(dst) + 0,
	d1 = (__m128i*)(dst) + 1,
	d2 = (__m128i*)(dst) + 2,
	d3 = (__m128i*)(dst) + 3;

	auto ANDed = _mm_and_si128(s3, _mm_and_si128(s2, _mm_and_si128(s1, s0)));
	if (_mm_testc_si128(ANDed, alphaMask)) {
	// All 16 source pixels are opaque. SrcOver becomes Src.
	_mm_storeu_si128(d0, s0);
	_mm_storeu_si128(d1, s1);
	_mm_storeu_si128(d2, s2);
	_mm_storeu_si128(d3, s3);
	src += 16;
	dst += 16;
	len -= 16;
	continue;
	}

	// TODO: This math is wrong.
	// Do SrcOver.
	_mm_storeu_si128(d0, SkPMSrcOver_SSE2(s0, _mm_loadu_si128(d0)));
	_mm_storeu_si128(d1, SkPMSrcOver_SSE2(s1, _mm_loadu_si128(d1)));
	_mm_storeu_si128(d2, SkPMSrcOver_SSE2(s2, _mm_loadu_si128(d2)));
	_mm_storeu_si128(d3, SkPMSrcOver_SSE2(s3, _mm_loadu_si128(d3)));
	src += 16;
	dst += 16;
	len -= 16;
	}

	#elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
	while (len >= 16) {
	// Load 16 source pixels.
	auto s0 = _mm_loadu_si128((const __m128i*)(src) + 0),
	s1 = _mm_loadu_si128((const __m128i*)(src) + 1),
	s2 = _mm_loadu_si128((const __m128i*)(src) + 2),
	s3 = _mm_loadu_si128((const __m128i*)(src) + 3);

	const auto alphaMask = _mm_set1_epi32(0xFF000000);

	auto ORed = _mm_or_si128(s3, _mm_or_si128(s2, _mm_or_si128(s1, s0)));
	if (0xffff == _mm_movemask_epi8(_mm_cmpeq_epi8(_mm_and_si128(ORed, alphaMask),
	_mm_setzero_si128()))) {
	// All 16 source pixels are transparent. Nothing to do.
	src += 16;
	dst += 16;
	len -= 16;
	continue;
	}

	auto d0 = (__m128i*)(dst) + 0,
	d1 = (__m128i*)(dst) + 1,
	d2 = (__m128i*)(dst) + 2,
	d3 = (__m128i*)(dst) + 3;

	auto ANDed = _mm_and_si128(s3, _mm_and_si128(s2, _mm_and_si128(s1, s0)));
	if (0xffff == _mm_movemask_epi8(_mm_cmpeq_epi8(_mm_and_si128(ANDed, alphaMask),
	alphaMask))) {
	// All 16 source pixels are opaque. SrcOver becomes Src.
	_mm_storeu_si128(d0, s0);
	_mm_storeu_si128(d1, s1);
	_mm_storeu_si128(d2, s2);
	_mm_storeu_si128(d3, s3);
	src += 16;
	dst += 16;
	len -= 16;
	continue;
	}

	// TODO: This math is wrong.
	// Do SrcOver.
	_mm_storeu_si128(d0, SkPMSrcOver_SSE2(s0, _mm_loadu_si128(d0)));
	_mm_storeu_si128(d1, SkPMSrcOver_SSE2(s1, _mm_loadu_si128(d1)));
	_mm_storeu_si128(d2, SkPMSrcOver_SSE2(s2, _mm_loadu_si128(d2)));
	_mm_storeu_si128(d3, SkPMSrcOver_SSE2(s3, _mm_loadu_si128(d3)));

	src += 16;
	dst += 16;
	len -= 16;
	}

	#elif defined(SK_ARM_HAS_NEON)
	// Do 8-pixels at a time. A 16-pixels at a time version of this code was also tested, but it
	// underperformed on some of the platforms under test for inputs with frequent transitions of
	// alpha (corresponding to changes of the conditions [~]alpha_u64 == 0 below). It may be worth
	// revisiting the situation in the future.
	while (len >= 8) {
	// Load 8 pixels in 4 NEON registers. src_col.val[i] will contain the same color component
	// for 8 consecutive pixels (e.g. src_col.val[3] will contain all alpha components of 8
	// pixels).
	uint8x8x4_t src_col = vld4_u8(reinterpret_cast<const uint8_t*>(src));
	src += 8;
	len -= 8;

	// We now detect 2 special cases: the first occurs when all alphas are zero (the 8 pixels
	// are all transparent), the second when all alphas are fully set (they are all opaque).
	uint8x8_t alphas = src_col.val[3];
	uint64_t alphas_u64 = vget_lane_u64(vreinterpret_u64_u8(alphas), 0);
	if (alphas_u64 == 0) {
	// All pixels transparent.
	dst += 8;
	continue;
	}

	if (~alphas_u64 == 0) {
	// All pixels opaque.
	vst4_u8(reinterpret_cast<uint8_t*>(dst), src_col);
	dst += 8;
	continue;
	}

	uint8x8x4_t dst_col = vld4_u8(reinterpret_cast<uint8_t*>(dst));
	vst4_u8(reinterpret_cast<uint8_t*>(dst), SkPMSrcOver_neon8(dst_col, src_col));
	dst += 8;
	}

	// Deal with leftover pixels.
	for (; len >= 2; len -= 2, src += 2, dst += 2) {
	uint8x8_t src2 = vld1_u8(reinterpret_cast<const uint8_t*>(src));
	uint8x8_t dst2 = vld1_u8(reinterpret_cast<const uint8_t*>(dst));
	vst1_u8(reinterpret_cast<uint8_t*>(dst), SkPMSrcOver_neon2(dst2, src2));
	}

	if (len != 0) {
	uint8x8_t result = SkPMSrcOver_neon2(vcreate_u8(dst), vcreate_u8(src));
	vst1_lane_u32(dst, vreinterpret_u32_u8(result), 0);
	}
	return;
	#endif

	while (len-- > 0) {
	// This 0xFF000000 is not semantically necessary, but for compatibility
	// with chromium:611002 we need to keep it until we figure out where
	// the non-premultiplied src values (like 0x00FFFFFF) are coming from.
	// TODO(mtklein): sort this out and assert *src is premul here.
	if (*src & 0xFF000000) {
	dst = (src >= 0xFF000000) ? src : SkPMSrcOver(src, *dst);
	}
	src++;
	dst++;
	}
	}

	} // SK_OPTS_NS

	#endif//SkBlitRow_opts_DEFINED