ARM Skia NEON patches - 36 - Color32

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 950e4f71d124e6c6682082913f5252924bc52e4b..9503323d87a42900bd248e1a649f571acf90fbf9 100644
--- a/src/opts/SkBlitRow_opts_arm_neon.cpp
+++ b/src/opts/SkBlitRow_opts_arm_neon.cpp
@@ -1384,84 +1384,88 @@ void Color32_arm_neon(SkPMColor* dst, const SkPMColor* src, int count,
     unsigned colorA = SkGetPackedA32(color);
     if (255 == colorA) {
         sk_memset32(dst, color, count);
-    } else {
-        unsigned scale = 256 - SkAlpha255To256(colorA);
+        return;
+    }
 
-        if (count >= 8) {
-            // at the end of this assembly, count will have been decremented
-            // to a negative value. That is, if count mod 8 = x, it will be
-            // -8 +x coming out.
-            asm volatile (
-                PLD128(src, 0)
-
-                "vdup.32    q0, %[color]                \n\t"
-
-                PLD128(src, 128)
-
-                // scale numerical interval [0-255], so load as 8 bits
-                "vdup.8     d2, %[scale]                \n\t"
-
-                PLD128(src, 256)
-
-                "subs       %[count], %[count], #8      \n\t"
-
-                PLD128(src, 384)
-
-                "Loop_Color32:                          \n\t"
-
-                // load src color, 8 pixels, 4 64 bit registers
-                // (and increment src).
-                "vld1.32    {d4-d7}, [%[src]]!          \n\t"
-
-                PLD128(src, 384)
-
-                // multiply long by scale, 64 bits at a time,
-                // destination into a 128 bit register.
-                "vmull.u8   q4, d4, d2                  \n\t"
-                "vmull.u8   q5, d5, d2                  \n\t"
-                "vmull.u8   q6, d6, d2                  \n\t"
-                "vmull.u8   q7, d7, d2                  \n\t"
-
-                // shift the 128 bit registers, containing the 16
-                // bit scaled values back to 8 bits, narrowing the
-                // results to 64 bit registers.
-                "vshrn.i16  d8, q4, #8                  \n\t"
-                "vshrn.i16  d9, q5, #8                  \n\t"
-                "vshrn.i16  d10, q6, #8                 \n\t"
-                "vshrn.i16  d11, q7, #8                 \n\t"
-
-                // adding back the color, using 128 bit registers.
-                "vadd.i8    q6, q4, q0                  \n\t"
-                "vadd.i8    q7, q5, q0                  \n\t"
-
-                // store back the 8 calculated pixels (2 128 bit
-                // registers), and increment dst.
-                "vst1.32    {d12-d15}, [%[dst]]!        \n\t"
-
-                "subs       %[count], %[count], #8      \n\t"
-                "bge        Loop_Color32                \n\t"
-                : [src] "+r" (src), [dst] "+r" (dst), [count] "+r" (count)
-                : [color] "r" (color), [scale] "r" (scale)
-                : "cc", "memory",
-                  "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
-                  "d8", "d9", "d10", "d11", "d12", "d13", "d14", "d15"
-                          );
-            // At this point, if we went through the inline assembly, count is
-            // a negative value:
-            // if the value is -8, there is no pixel left to process.
-            // if the value is -7, there is one pixel left to process
-            // ...
-            // And'ing it with 7 will give us the number of pixels
-            // left to process.
-            count = count & 0x7;
-        }
+    unsigned scale = 256 - SkAlpha255To256(colorA);
 
-        while (count > 0) {
-            *dst = color + SkAlphaMulQ(*src, scale);
-            src += 1;
-            dst += 1;
-            count--;
-        }
+    if (count >= 8) {
+        uint32x4_t vcolor;
+        uint8x8_t vscale;
+
+        vcolor = vdupq_n_u32(color);
+
+        // scale numerical interval [0-255], so load as 8 bits
+        vscale = vdup_n_u8(scale);
+
+        do {
+            // load src color, 8 pixels, 4 64 bit registers
+            // (and increment src).
+            uint32x2x4_t vsrc;
+#if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6))
+            asm (
+                "vld1.32    %h[vsrc], [%[src]]!"
+                : [vsrc] "=w" (vsrc), [src] "+r" (src)
+                : :
+            );
+#else // (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6))
+            vsrc.val[0] = vld1_u32(src);
+            vsrc.val[1] = vld1_u32(src+2);
+            vsrc.val[2] = vld1_u32(src+4);
+            vsrc.val[3] = vld1_u32(src+6);
+            src += 8;
+#endif
+
+            // multiply long by scale, 64 bits at a time,
+            // destination into a 128 bit register.
+            uint16x8x4_t vtmp;
+            vtmp.val[0] = vmull_u8(vreinterpret_u8_u32(vsrc.val[0]), vscale);
+            vtmp.val[1] = vmull_u8(vreinterpret_u8_u32(vsrc.val[1]), vscale);
+            vtmp.val[2] = vmull_u8(vreinterpret_u8_u32(vsrc.val[2]), vscale);
+            vtmp.val[3] = vmull_u8(vreinterpret_u8_u32(vsrc.val[3]), vscale);
+
+            // shift the 128 bit registers, containing the 16
+            // bit scaled values back to 8 bits, narrowing the
+            // results to 64 bit registers.
+            uint8x16x2_t vres;
+            vres.val[0] = vcombine_u8(
+                            vshrn_n_u16(vtmp.val[0], 8),
+                            vshrn_n_u16(vtmp.val[1], 8));
+            vres.val[1] = vcombine_u8(
+                            vshrn_n_u16(vtmp.val[2], 8),
+                            vshrn_n_u16(vtmp.val[3], 8));
+
+            // adding back the color, using 128 bit registers.
+            uint32x4x2_t vdst;
+            vdst.val[0] = vreinterpretq_u32_u8(vres.val[0] +
+                                               vreinterpretq_u8_u32(vcolor));
+            vdst.val[1] = vreinterpretq_u32_u8(vres.val[1] +
+                                               vreinterpretq_u8_u32(vcolor));
+
+            // store back the 8 calculated pixels (2 128 bit
+            // registers), and increment dst.
+#if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6))
+            asm (
+                "vst1.32    %h[vdst], [%[dst]]!"
+                : [dst] "+r" (dst)
+                : [vdst] "w" (vdst)
+                : "memory"
+            );
+#else // (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6))
+            vst1q_u32(dst, vdst.val[0]);
+            vst1q_u32(dst+4, vdst.val[1]);
+            dst += 8;
+#endif
+            count -= 8;
+
+        } while (count >= 8);
+    }
+
+    while (count > 0) {
+        *dst = color + SkAlphaMulQ(*src, scale);
+        src += 1;
+        dst += 1;
+        count--;
     }
 }