/*
* Copyright 2013 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkBitmap.h"
#include "SkColorPriv.h"
#include "SkBlurImage_opts.h"
#include "SkRect.h"
#include <arm_neon.h>
namespace {
enum BlurDirection {
kX, kY
};
/**
* Helper function to load 2 pixels from diffent rows to a 8x8 NEON register
* and also pre-load pixels for future read
*/
template<BlurDirection srcDirection>
inline uint8x8_t load_2_pixels(const SkPMColor* src, int srcStride) {
if (srcDirection == kX) {
uint32x2_t temp = vdup_n_u32(0);
// 10% faster by adding these 2 prefetches
SK_PREFETCH(src + 16);
SK_PREFETCH(src + srcStride + 16);
return vreinterpret_u8_u32(vld1_lane_u32(src + srcStride, vld1_lane_u32(src, temp, 0), 1));
} else {
return vld1_u8((uint8_t*)src);
}
}
/**
* Helper function to store the low 8-bits from a 16x8 NEON register to 2 rows
*/
template<BlurDirection dstDirection>
inline void store_2_pixels(uint16x8_t result16x8, SkPMColor* dst, int dstStride) {
if (dstDirection == kX) {
uint32x2_t temp = vreinterpret_u32_u8(vmovn_u16(result16x8));
vst1_lane_u32(dst, temp, 0);
vst1_lane_u32(dst + dstStride, temp, 1);
} else {
uint8x8_t temp = vmovn_u16(result16x8);
vst1_u8((uint8_t*)dst, temp);
}
}
/**
* fast path for kernel size less than 128
*/
template<BlurDirection srcDirection, BlurDirection dstDirection>
void SkDoubleRowBoxBlur_NEON(const SkPMColor** src, int srcStride, SkPMColor** dst, int kernelSize,
int leftOffset, int rightOffset, int width, int* height)
{
const int rightBorder = SkMin32(rightOffset + 1, width);
const int srcStrideX = srcDirection == kX ? 1 : srcStride;
const int dstStrideX = dstDirection == kX ? 1 : *height;
const int srcStrideY = srcDirection == kX ? srcStride : 1;
const int dstStrideY = dstDirection == kX ? width : 1;
const uint16x8_t scale = vdupq_n_u16((1 << 15) / kernelSize);
for (; *height >= 2; *height -= 2) {
uint16x8_t sum = vdupq_n_u16(0);
const SkPMColor* p = *src;
for (int i = 0; i < rightBorder; i++) {
sum = vaddw_u8(sum,
load_2_pixels<srcDirection>(p, srcStride));
p += srcStrideX;
}
const SkPMColor* sptr = *src;
SkPMColor* dptr = *dst;
for (int x = 0; x < width; x++) {
// val = (sum * scale * 2 + 0x8000) >> 16
uint16x8_t resultPixels = vreinterpretq_u16_s16(vqrdmulhq_s16(
vreinterpretq_s16_u16(sum), vreinterpretq_s16_u16(scale)));
store_2_pixels<dstDirection>(resultPixels, dptr, width);
if (x >= leftOffset) {
sum = vsubw_u8(sum,
load_2_pixels<srcDirection>(sptr - leftOffset * srcStrideX, srcStride));
}
if (x + rightOffset + 1 < width) {
sum = vaddw_u8(sum,
load_2_pixels<srcDirection>(sptr + (rightOffset + 1) * srcStrideX, srcStride));
}
sptr += srcStrideX;
dptr += dstStrideX;
}
*src += srcStrideY * 2;
*dst += dstStrideY * 2;
}
}
/**
* Helper function to spread the components of a 32-bit integer into the
* lower 8 bits of each 16-bit element of a NEON register.
*/
static inline uint16x4_t expand(uint32_t a) {
// ( ARGB ) -> ( ARGB ARGB ) -> ( A R G B A R G B )
uint8x8_t v8 = vreinterpret_u8_u32(vdup_n_u32(a));
// ( A R G B A R G B ) -> ( 0A 0R 0G 0B 0A 0R 0G 0B ) -> ( 0A 0R 0G 0B )
return vget_low_u16(vmovl_u8(v8));
}
template<BlurDirection srcDirection, BlurDirection dstDirection>
void SkBoxBlur_NEON(const SkPMColor* src, int srcStride, SkPMColor* dst, int kernelSize,
int leftOffset, int rightOffset, int width, int height)
{
const int rightBorder = SkMin32(rightOffset + 1, width);
const int srcStrideX = srcDirection == kX ? 1 : srcStride;
const int dstStrideX = dstDirection == kX ? 1 : height;
const int srcStrideY = srcDirection == kX ? srcStride : 1;
const int dstStrideY = dstDirection == kX ? width : 1;
const uint32x4_t scale = vdupq_n_u32((1 << 24) / kernelSize);
const uint32x4_t half = vdupq_n_u32(1 << 23);
if (1 < kernelSize && kernelSize < 128)
{
SkDoubleRowBoxBlur_NEON<srcDirection, dstDirection>(&src, srcStride, &dst, kernelSize,
leftOffset, rightOffset, width, &height);
}
for (; height > 0; height--) {
uint32x4_t sum = vdupq_n_u32(0);
const SkPMColor* p = src;
for (int i = 0; i < rightBorder; ++i) {
sum = vaddw_u16(sum, expand(*p));
p += srcStrideX;
}
const SkPMColor* sptr = src;
SkPMColor* dptr = dst;
for (int x = 0; x < width; ++x) {
// ( half+sumA*scale half+sumR*scale half+sumG*scale half+sumB*scale )
uint32x4_t result = vmlaq_u32(half, sum, scale);
// Saturated conversion to 16-bit.
// ( AAAA RRRR GGGG BBBB ) -> ( 0A 0R 0G 0B )
uint16x4_t result16 = vqshrn_n_u32(result, 16);
// Saturated conversion to 8-bit.
// ( 0A 0R 0G 0B ) -> ( 0A 0R 0G 0B 0A 0R 0G 0B ) -> ( A R G B A R G B )
uint8x8_t result8 = vqshrn_n_u16(vcombine_u16(result16, result16), 8);
// ( A R G B A R G B ) -> ( ARGB ARGB ) -> ( ARGB )
// Store low 32 bits to destination.
vst1_lane_u32(dptr, vreinterpret_u32_u8(result8), 0);
if (x >= leftOffset) {
const SkPMColor* l = sptr - leftOffset * srcStrideX;
sum = vsubw_u16(sum, expand(*l));
}
if (x + rightOffset + 1 < width) {
const SkPMColor* r = sptr + (rightOffset + 1) * srcStrideX;
sum = vaddw_u16(sum, expand(*r));
}
sptr += srcStrideX;
if (srcDirection == kX) {
SK_PREFETCH(sptr + (rightOffset + 16) * srcStrideX);
}
dptr += dstStrideX;
}
src += srcStrideY;
dst += dstStrideY;
}
}
} // namespace
bool SkBoxBlurGetPlatformProcs_NEON(SkBoxBlurProc* boxBlurX,
SkBoxBlurProc* boxBlurXY,
SkBoxBlurProc* boxBlurYX) {
*boxBlurX = SkBoxBlur_NEON<kX, kX>;
*boxBlurXY = SkBoxBlur_NEON<kX, kY>;
*boxBlurYX = SkBoxBlur_NEON<kY, kX>;
return true;
}