Optimize RGB16 blitH functions with NEON for ARM platform.

src/opts/SkBlitMask_opts_arm_neon.cpp

Index: src/opts/SkBlitMask_opts_arm_neon.cpp
diff --git a/src/opts/SkBlitMask_opts_arm_neon.cpp b/src/opts/SkBlitMask_opts_arm_neon.cpp
index 3361a5d19dd777191700bbe8f4f6111ddb7c1d7a..e9ca804ce7d7407819207218657d3e393ba694e8 100644
--- a/src/opts/SkBlitMask_opts_arm_neon.cpp
+++ b/src/opts/SkBlitMask_opts_arm_neon.cpp
@@ -332,3 +332,49 @@ void SkRGB16BlitterBlitV_neon(uint16_t* device,
 
 #undef LOAD_LANE_16
 #undef STORE_LANE_16
+
+void SkRGB16BlitterBlitH_neon(uint16_t* device,
+                              int height,

[mtklein, 2015/07/29 14:07:11]

Let's call this width or count or n?  height is rather confusing, given that
we're moving horizontally.

[yang.zhang, 2015/07/30 05:35:34]

Done.

+                              unsigned scale,
+                              uint32_t src32) {
+    if (height >= 8)
+    {
+        // prepare constants
+        uint16x8_t vdev = vdupq_n_u16(0);
+        uint16x8_t vmaskq_g16 = vdupq_n_u16(SK_G16_MASK_IN_PLACE);
+        uint16x8_t vmaskq_ng16 = vdupq_n_u16(~SK_G16_MASK_IN_PLACE);
+        uint32x4_t vsrc32 = vdupq_n_u32(src32);
+        uint32x4_t vscale5 = vdupq_n_u32((uint32_t)scale);
+
+        while (height >= 8){
+            vdev = vld1q_u16(device);
+
+            // Expand_rgb_16
+            uint16x8x2_t vdst = vzipq_u16((vdev & vmaskq_ng16), (vdev & vmaskq_g16));
+            uint32x4_t vdst32_lo = vmulq_u32(vreinterpretq_u32_u16(vdst.val[0]), vscale5);
+            uint32x4_t vdst32_hi = vmulq_u32(vreinterpretq_u32_u16(vdst.val[1]), vscale5);
+
+            // Compact_rgb_16
+            vdst32_lo = vaddq_u32(vdst32_lo, vsrc32);
+            vdst32_hi = vaddq_u32(vdst32_hi, vsrc32);
+            vdst32_lo = vshrq_n_u32(vdst32_lo, 5);
+            vdst32_hi = vshrq_n_u32(vdst32_hi, 5);
+
+            uint16x4_t vtmp_lo = vmovn_u32(vdst32_lo) & vget_low_u16(vmaskq_ng16);
+            uint16x4_t vtmp_hi = vshrn_n_u32(vdst32_lo, 16) & vget_low_u16(vmaskq_g16);
+            uint16x4_t vdst16_lo = vorr_u16(vtmp_lo, vtmp_hi);
+            vtmp_lo = vmovn_u32(vdst32_hi) & vget_low_u16(vmaskq_ng16);
+            vtmp_hi = vshrn_n_u32(vdst32_hi, 16) & vget_low_u16(vmaskq_g16);
+            uint16x4_t vdst16_hi = vorr_u16(vtmp_lo, vtmp_hi);
+
+            vst1q_u16(device, vcombine_u16(vdst16_lo, vdst16_hi));
+            device += 8;
+            height -= 8;
+        }
+    }
+    while (height != 0){
+        uint32_t dst32 = SkExpand_rgb_16(*device) * scale;
+        *device++ = SkCompact_rgb_16((src32 + dst32) >> 5);
+        height--;
+    }
+}