skia: blend32_16_row for neon version

src/opts/SkBlitRow_opts_arm_neon.cpp

Index: src/opts/SkBlitRow_opts_arm_neon.cpp
diff --git a/src/opts/SkBlitRow_opts_arm_neon.cpp b/src/opts/SkBlitRow_opts_arm_neon.cpp
index a1ff1722b5f5e7c820bed0a3c17f6af90f2e7cba..8981fd7fee6967ad23f2d3713099890f4dd30304 100644
--- a/src/opts/SkBlitRow_opts_arm_neon.cpp
+++ b/src/opts/SkBlitRow_opts_arm_neon.cpp
@@ -465,6 +465,130 @@ void S32A_D565_Opaque_neon(uint16_t* SK_RESTRICT dst,
 }
 #endif // #ifdef SK_CPU_ARM32
 
+static uint32_t pmcolor_to_expand16(SkPMColor c) {
+    unsigned r = SkGetPackedR32(c);
+    unsigned g = SkGetPackedG32(c);
+    unsigned b = SkGetPackedB32(c);
+    return (g << 24) | (r << 13) | (b << 2);
+}
+
+void Color32A_D565_neon(uint16_t dst[], SkPMColor src, int count, int x, int y) {
+    uint32_t src_expand;
+    unsigned scale;
+    uint16x8_t vmask_blue;
+
+    if (count <= 0) return;
+    SkASSERT(((size_t)dst & 0x01) == 0);
+
+    /*
+     * This preamble code is in order to make dst aligned to 8 bytes
+     * in the next mutiple bytes read & write access.
+     */
+    src_expand = pmcolor_to_expand16(src);
+    scale = SkAlpha255To256(0xFF - SkGetPackedA32(src)) >> 3;
+
+#define DST_ALIGN 8
+
+    /*
+     * preamble_size is in byte, meantime, this blend32_16_row_neon updates 2 bytes at a time.
+     */
+    int preamble_size = (DST_ALIGN - (size_t)dst) & (DST_ALIGN - 1);
+
+    for (int i = 0; i < preamble_size; i+=2, dst++) {
+        uint32_t dst_expand = SkExpand_rgb_16(*dst) * scale;
+        *dst = SkCompact_rgb_16((src_expand + dst_expand) >> 5);
+        if (--count == 0)
+            break;
+    }
+
+    int count16 = 0;
+    count16 = count >> 4;
+    vmask_blue = vmovq_n_u16(SK_B16_MASK);
+
+    if (count16) {
+        uint16x8_t wide_sr;
+        uint16x8_t wide_sg;
+        uint16x8_t wide_sb;
+        uint16x8_t wide_256_sa;
+
+        unsigned sr = SkGetPackedR32(src);
+        unsigned sg = SkGetPackedG32(src);
+        unsigned sb = SkGetPackedB32(src);
+        unsigned sa = SkGetPackedA32(src);
+
+        // Operation: dst_rgb = src_rgb + ((256 - src_a) >> 3) x dst_rgb
+        // sr: 8-bit based, dr: 5-bit based, with dr x ((256-sa)>>3), 5-bit left shifted,
+        //thus, for sr, do 2-bit left shift to match MSB : (8 + 2 = 5 + 5)
+        wide_sr = vshlq_n_u16(vmovl_u8(vdup_n_u8(sr)), 2); // widen and src_red shift
+
+        // sg: 8-bit based, dg: 6-bit based, with dg x ((256-sa)>>3), 5-bit left shifted,
+        //thus, for sg, do 3-bit left shift to match MSB : (8 + 3 = 6 + 5)
+        wide_sg = vshlq_n_u16(vmovl_u8(vdup_n_u8(sg)), 3); // widen and src_grn shift
+
+        // sb: 8-bit based, db: 5-bit based, with db x ((256-sa)>>3), 5-bit left shifted,
+        //thus, for sb, do 2-bit left shift to match MSB : (8 + 2 = 5 + 5)
+        wide_sb = vshlq_n_u16(vmovl_u8(vdup_n_u8(sb)), 2); // widen and src blu shift
+
+        wide_256_sa =
+            vshrq_n_u16(vsubw_u8(vdupq_n_u16(256), vdup_n_u8(sa)), 3); // (256 - sa) >> 3
+
+        while (count16-- > 0) {
+            uint16x8_t vdst1, vdst1_r, vdst1_g, vdst1_b;
+            uint16x8_t vdst2, vdst2_r, vdst2_g, vdst2_b;
+            vdst1 = vld1q_u16(dst);
+            dst += 8;
+            vdst2 = vld1q_u16(dst);
+            dst -= 8;    //to store dst again.
+
+            vdst1_g = vshlq_n_u16(vdst1, SK_R16_BITS);                 // shift green to top of lanes
+            vdst1_b = vdst1 & vmask_blue;                              // extract blue
+            vdst1_r = vshrq_n_u16(vdst1, SK_R16_SHIFT);                // extract red
+            vdst1_g = vshrq_n_u16(vdst1_g, SK_R16_BITS + SK_B16_BITS); // extract green
+
+            vdst2_g = vshlq_n_u16(vdst2, SK_R16_BITS);                 // shift green to top of lanes
+            vdst2_b = vdst2 & vmask_blue;                              // extract blue
+            vdst2_r = vshrq_n_u16(vdst2, SK_R16_SHIFT);                // extract red
+            vdst2_g = vshrq_n_u16(vdst2_g, SK_R16_BITS + SK_B16_BITS); // extract green
+
+            vdst1_r = vmlaq_u16(wide_sr, wide_256_sa, vdst1_r);        // sr + (256-sa) x dr1
+            vdst1_g = vmlaq_u16(wide_sg, wide_256_sa, vdst1_g);        // sg + (256-sa) x dg1
+            vdst1_b = vmlaq_u16(wide_sb, wide_256_sa, vdst1_b);        // sb + (256-sa) x db1
+
+            vdst2_r = vmlaq_u16(wide_sr, wide_256_sa, vdst2_r);        // sr + (256-sa) x dr2
+            vdst2_g = vmlaq_u16(wide_sg, wide_256_sa, vdst2_g);        // sg + (256-sa) x dg2
+            vdst2_b = vmlaq_u16(wide_sb, wide_256_sa, vdst2_b);        // sb + (256-sa) x db2
+
+            vdst1_r = vshrq_n_u16(vdst1_r, 5);                         // 5-bit right shift for 5-bit red
+            vdst1_g = vshrq_n_u16(vdst1_g, 5);                         // 5-bit right shift for 6-bit green
+            vdst1_b = vshrq_n_u16(vdst1_b, 5);                         // 5-bit right shift for 5-bit blue
+
+            vdst1 = vsliq_n_u16(vdst1_b, vdst1_g, SK_G16_SHIFT);       // insert green into blue
+            vdst1 = vsliq_n_u16(vdst1, vdst1_r, SK_R16_SHIFT);         // insert red into green/blue
+
+            vdst2_r = vshrq_n_u16(vdst2_r, 5);                         // 5-bit right shift for 5-bit red
+            vdst2_g = vshrq_n_u16(vdst2_g, 5);                         // 5-bit right shift for 6-bit green
+            vdst2_b = vshrq_n_u16(vdst2_b, 5);                         // 5-bit right shift for 5-bit blue
+
+            vdst2 = vsliq_n_u16(vdst2_b, vdst2_g, SK_G16_SHIFT);       // insert green into blue
+            vdst2 = vsliq_n_u16(vdst2, vdst2_r, SK_R16_SHIFT);         // insert red into green/blue
+
+            vst1q_u16(dst, vdst1);
+            dst += 8;
+            vst1q_u16(dst, vdst2);
+            dst += 8;
+        }
+    }
+
+    count &= 0xF;
+    if (count > 0) {
+        do {
+            uint32_t dst_expand = SkExpand_rgb_16(*dst) * scale;
+            *dst = SkCompact_rgb_16((src_expand + dst_expand) >> 5);
+            dst += 1;
+        } while (--count != 0);
+    }
+}
+
 static inline uint16x8_t SkDiv255Round_neon8(uint16x8_t prod) {
     prod += vdupq_n_u16(128);
     prod += vshrq_n_u16(prod, 8);
@@ -1665,6 +1789,13 @@ const SkBlitRow::Proc16 sk_blitrow_platform_565_procs_arm_neon[] = {
     NULL,   // S32A_D565_Blend_Dither
 };
 
+const SkBlitRow::ColorProc16 sk_blitrow_platform_565_colorprocs_arm_neon[] = {
+    Color32A_D565_neon,    // Color32_D565,
+    Color32A_D565_neon,    // Color32A_D565,
+    Color32A_D565_neon,    // Color32_D565_Dither,
+    Color32A_D565_neon,    // Color32A_D565_Dither
+};
+
 const SkBlitRow::Proc32 sk_blitrow_platform_32_procs_arm_neon[] = {
     NULL,   // S32_Opaque,
     S32_Blend_BlitRow32_neon,        // S32_Blend,