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/*
* 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 "include/private/SkColorData.h"
#include "src/base/SkMSAN.h"
#include "src/base/SkVx.h"
// Helpers for blit_row_s32a_opaque(),
// then blit_row_s32a_opaque() itself,
// then unrelated blit_row_color32() at the bottom.
//
// To keep Skia resistant to timing attacks, it's important not to branch on pixel data.
// In particular, don't be tempted to [v]ptest, pmovmskb, etc. to branch on the source alpha.
#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SKX
#include <immintrin.h>
static inline __m512i SkPMSrcOver_SKX(const __m512i& src, const __m512i& dst) {
// Detailed explanations in SkPMSrcOver_AVX2
// b = s + (d*(256-srcA)) >> 8
// Shuffle each pixel's srcA to the low byte of each 16-bit half of the pixel.
const uint8_t _ = -1; // fills a literal 0 byte.
const uint8_t mask[64] = { 3, _,3, _, 7, _,7, _, 11,_,11,_, 15,_,15,_,
19,_,19,_, 23,_,23,_, 27,_,27,_, 31,_,31,_,
35,_,35,_, 39,_,39,_, 43,_,43,_, 47,_,47,_,
51,_,51,_, 55,_,55,_, 59,_,59,_, 63,_,63,_ };
__m512i srcA_x2 = _mm512_shuffle_epi8(src, _mm512_loadu_si512(mask));
__m512i scale_x2 = _mm512_sub_epi16(_mm512_set1_epi16(256),
srcA_x2);
// Scale red and blue, leaving results in the low byte of each 16-bit lane.
__m512i rb = _mm512_and_si512(_mm512_set1_epi32(0x00ff00ff), dst);
rb = _mm512_mullo_epi16(rb, scale_x2);
rb = _mm512_srli_epi16(rb, 8);
// Scale green and alpha, leaving results in the high byte, masking off the low bits.
__m512i ga = _mm512_srli_epi16(dst, 8);
ga = _mm512_mullo_epi16(ga, scale_x2);
ga = _mm512_andnot_si512(_mm512_set1_epi32(0x00ff00ff), ga);
return _mm512_adds_epu8(src, _mm512_or_si512(rb, ga));
}
#endif
#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX2
#include <immintrin.h>
static inline __m256i SkPMSrcOver_AVX2(const __m256i& src, const __m256i& dst) {
// Abstractly srcover is
// b = s + d*(1-srcA)
//
// In terms of unorm8 bytes, that works out to
// b = s + (d*(255-srcA) + 127) / 255
//
// But we approximate that to within a bit with
// b = s + (d*(255-srcA) + d) / 256
// a.k.a
// b = s + (d*(256-srcA)) >> 8
// The bottleneck of this math is the multiply, and we want to do it as
// narrowly as possible, here getting inputs into 16-bit lanes and
// using 16-bit multiplies. We can do twice as many multiplies at once
// as using naive 32-bit multiplies, and on top of that, the 16-bit multiplies
// are themselves a couple cycles quicker. Win-win.
// We'll get everything in 16-bit lanes for two multiplies, one
// handling dst red and blue, the other green and alpha. (They're
// conveniently 16-bits apart, you see.) We don't need the individual
// src channels beyond alpha until the very end when we do the "s + "
// add, and we don't even need to unpack them; the adds cannot overflow.
// Shuffle each pixel's srcA to the low byte of each 16-bit half of the pixel.
const int _ = -1; // fills a literal 0 byte.
__m256i srcA_x2 = _mm256_shuffle_epi8(src,
_mm256_setr_epi8(3,_,3,_, 7,_,7,_, 11,_,11,_, 15,_,15,_,
3,_,3,_, 7,_,7,_, 11,_,11,_, 15,_,15,_));
__m256i scale_x2 = _mm256_sub_epi16(_mm256_set1_epi16(256),
srcA_x2);
// Scale red and blue, leaving results in the low byte of each 16-bit lane.
__m256i rb = _mm256_and_si256(_mm256_set1_epi32(0x00ff00ff), dst);
rb = _mm256_mullo_epi16(rb, scale_x2);
rb = _mm256_srli_epi16 (rb, 8);
// Scale green and alpha, leaving results in the high byte, masking off the low bits.
__m256i ga = _mm256_srli_epi16(dst, 8);
ga = _mm256_mullo_epi16(ga, scale_x2);
ga = _mm256_andnot_si256(_mm256_set1_epi32(0x00ff00ff), ga);
return _mm256_adds_epu8(src, _mm256_or_si256(rb, ga));
}
#endif
#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
#include <immintrin.h>
static inline __m128i SkPMSrcOver_SSE2(const __m128i& src, const __m128i& dst) {
__m128i scale = _mm_sub_epi32(_mm_set1_epi32(256),
_mm_srli_epi32(src, 24));
__m128i scale_x2 = _mm_or_si128(_mm_slli_epi32(scale, 16), scale);
__m128i rb = _mm_and_si128(_mm_set1_epi32(0x00ff00ff), dst);
rb = _mm_mullo_epi16(rb, scale_x2);
rb = _mm_srli_epi16(rb, 8);
__m128i ga = _mm_srli_epi16(dst, 8);
ga = _mm_mullo_epi16(ga, scale_x2);
ga = _mm_andnot_si128(_mm_set1_epi32(0x00ff00ff), ga);
return _mm_adds_epu8(src, _mm_or_si128(rb, ga));
}
#endif
#if defined(SK_ARM_HAS_NEON)
#include <arm_neon.h>
// SkMulDiv255Round() applied to each lane.
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));
}
static inline uint8x8x4_t SkPMSrcOver_neon8(uint8x8x4_t dst, uint8x8x4_t src) {
uint8x8_t nalphas = vmvn_u8(src.val[3]); // 256 - alpha
return {
vqadd_u8(src.val[0], SkMulDiv255Round_neon8(nalphas, dst.val[0])),
vqadd_u8(src.val[1], SkMulDiv255Round_neon8(nalphas, dst.val[1])),
vqadd_u8(src.val[2], SkMulDiv255Round_neon8(nalphas, dst.val[2])),
vqadd_u8(src.val[3], SkMulDiv255Round_neon8(nalphas, dst.val[3])),
};
}
// Variant assuming dst and src contain the color components of two consecutive pixels.
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 vqadd_u8(src, SkMulDiv255Round_neon8(nalphas, dst));
}
#endif
namespace SK_OPTS_NS {
/*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_SKX
while (len >= 16) {
_mm512_storeu_si512((__m512*)dst,
SkPMSrcOver_SKX(_mm512_loadu_si512((const __m512i*)src),
_mm512_loadu_si512((const __m512i*)dst)));
src += 16;
dst += 16;
len -= 16;
}
#endif
#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX2
while (len >= 8) {
_mm256_storeu_si256((__m256i*)dst,
SkPMSrcOver_AVX2(_mm256_loadu_si256((const __m256i*)src),
_mm256_loadu_si256((const __m256i*)dst)));
src += 8;
dst += 8;
len -= 8;
}
#endif
#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
while (len >= 4) {
_mm_storeu_si128((__m128i*)dst, SkPMSrcOver_SSE2(_mm_loadu_si128((const __m128i*)src),
_mm_loadu_si128((const __m128i*)dst)));
src += 4;
dst += 4;
len -= 4;
}
#endif
#if defined(SK_ARM_HAS_NEON)
while (len >= 8) {
vst4_u8((uint8_t*)dst, SkPMSrcOver_neon8(vld4_u8((const uint8_t*)dst),
vld4_u8((const uint8_t*)src)));
src += 8;
dst += 8;
len -= 8;
}
while (len >= 2) {
vst1_u8((uint8_t*)dst, SkPMSrcOver_neon2(vld1_u8((const uint8_t*)dst),
vld1_u8((const uint8_t*)src)));
src += 2;
dst += 2;
len -= 2;
}
if (len != 0) {
uint8x8_t result = SkPMSrcOver_neon2(vcreate_u8((uint64_t)*dst),
vcreate_u8((uint64_t)*src));
vst1_lane_u32(dst, vreinterpret_u32_u8(result), 0);
}
return;
#endif
while (len --> 0) {
*dst = SkPMSrcOver(*src, *dst);
src++;
dst++;
}
}
// Blend constant color over count src pixels, writing into dst.
/*not static*/
inline void blit_row_color32(SkPMColor* dst, const SkPMColor* src, int count, SkPMColor color) {
constexpr int N = 4; // 8, 16 also reasonable choices
using U32 = skvx::Vec< N, uint32_t>;
using U16 = skvx::Vec<4*N, uint16_t>;
using U8 = skvx::Vec<4*N, uint8_t>;
auto kernel = [color](U32 src) {
unsigned invA = 255 - SkGetPackedA32(color);
invA += invA >> 7;
SkASSERT(0 < invA && invA < 256); // We handle alpha == 0 or alpha == 255 specially.
// (src * invA + (color << 8) + 128) >> 8
// Should all fit in 16 bits.
U8 s = skvx::bit_pun<U8>(src),
a = U8(invA);
U16 c = skvx::cast<uint16_t>(skvx::bit_pun<U8>(U32(color))),
d = (mull(s,a) + (c << 8) + 128)>>8;
return skvx::bit_pun<U32>(skvx::cast<uint8_t>(d));
};
while (count >= N) {
kernel(U32::Load(src)).store(dst);
src += N;
dst += N;
count -= N;
}
while (count --> 0) {
*dst++ = kernel(U32{*src++})[0];
}
}
} // namespace SK_OPTS_NS
#endif//SkBlitRow_opts_DEFINED
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