Port SkBlurImage opts to SkOpts.

src/opts/SkBlurImage_opts_neon.cpp

-/*
- * 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;
-}