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Unified Diff: src/opts/SkBlurImage_opts_neon.cpp

Issue 105893003: NEON fast path for box blur (Closed) Base URL: https://skia.googlecode.com/svn/trunk
Patch Set: Created 7 years ago
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« expectations/gm/ignored-tests.txt ('K') | « gm/imageblur.cpp ('k') | no next file » | no next file with comments »
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Index: src/opts/SkBlurImage_opts_neon.cpp
diff --git a/src/opts/SkBlurImage_opts_neon.cpp b/src/opts/SkBlurImage_opts_neon.cpp
index 4e33d72d462562284c8feebe9cb1189ca851e52f..ebe17f05b4eea88d833b7b72c38159c087c8b7db 100644
--- a/src/opts/SkBlurImage_opts_neon.cpp
+++ b/src/opts/SkBlurImage_opts_neon.cpp
@@ -20,6 +20,86 @@ enum BlurDirection {
};
/**
+ * 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.
*/
@@ -42,7 +122,14 @@ void SkBoxBlur_NEON(const SkPMColor* src, int srcStride, SkPMColor* dst, int ker
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);
- for (int y = 0; y < height; ++y) {
+
+ if (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) {
@@ -77,8 +164,8 @@ void SkBoxBlur_NEON(const SkPMColor* src, int srcStride, SkPMColor* dst, int ker
sum = vaddw_u16(sum, expand(*r));
}
sptr += srcStrideX;
- if (srcDirection == kY) {
- SK_PREFETCH(sptr + (rightOffset + 1) * srcStrideX);
+ if (srcDirection == kX) {
+ SK_PREFETCH(sptr + (rightOffset + 16) * srcStrideX);
}
dptr += dstStrideX;
}
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