ARM Skia NEON patches - 16/17 - Blitmask

src/opts/SkColor_opts_neon.h

Index: src/opts/SkColor_opts_neon.h
diff --git a/src/opts/SkColor_opts_neon.h b/src/opts/SkColor_opts_neon.h
index f81239712ab5bba90fb21b6896f7edbb4e658044..85752f5558cd8263bdf6f4108c5c88d55e6ee9a2 100644
--- a/src/opts/SkColor_opts_neon.h
+++ b/src/opts/SkColor_opts_neon.h
@@ -2,6 +2,7 @@
 #define SkColor_opts_neon_DEFINED
 
 #include "SkTypes.h"
+#include "SkColorPriv.h"
 
 #include <arm_neon.h>
 
@@ -65,4 +66,20 @@ static inline uint16x8_t SkPixel32ToPixel16_neon8(uint8x8x4_t vsrc) {
     return ret;
 }
 
+/* This function blends 8 pixels of the same channel in the exact same way as
+ * SkBlend32.
+ */
+static inline uint8x8_t SkBlend32_neon8(uint8x8_t src, uint8x8_t dst, uint16x8_t scale) {
+    int16x8_t src_wide, dst_wide;
+
+    src_wide = vreinterpretq_s16_u16(vmovl_u8(src));
+    dst_wide = vreinterpretq_s16_u16(vmovl_u8(dst));
+
+    src_wide = (src_wide - dst_wide) * vreinterpretq_s16_u16(scale);
+
+    dst_wide += vshrq_n_s16(src_wide, 5);
+
+    return vmovn_u16(vreinterpretq_u16_s16(dst_wide));
+}
+
 #endif /* #ifndef SkColor_opts_neon_DEFINED */