remove U16 support, just support F16

src/core/SkXfermodeF16.cpp

Index: src/core/SkXfermodeF16.cpp
diff --git a/src/core/SkXfermodeF16.cpp b/src/core/SkXfermodeF16.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..dfcefa2de5ba4df925b4b7b0f5df349b5722a0bf
--- /dev/null
+++ b/src/core/SkXfermodeF16.cpp
@@ -0,0 +1,178 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkHalf.h"
+#include "SkPM4fPriv.h"
+#include "SkUtils.h"
+#include "SkXfermode.h"
+
+static Sk4f lerp_by_coverage(const Sk4f& src, const Sk4f& dst, uint8_t srcCoverage) {
+    return dst + (src - dst) * Sk4f(srcCoverage * (1/255.0f));
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static void xfer_1(const SkXfermode* xfer, uint64_t dst[], const SkPM4f* src, int count,
+                       const SkAlpha aa[]) {
+    SkXfermodeProc4f proc = xfer->getProc4f();
+    SkPM4f d;
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            Sk4f d4 = SkHalfToFloat_01(dst[i]);
+            d4.store(d.fVec);
+            Sk4f r4 = Sk4f::Load(proc(*src, d).fVec);
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(r4, d4, aa[i]));
+        }
+    } else {
+        for (int i = 0; i < count; ++i) {
+            SkHalfToFloat_01(dst[i]).store(d.fVec);
+            Sk4f r4 = Sk4f::Load(proc(*src, d).fVec);
+            dst[i] = SkFloatToHalf_01(r4);
+        }
+    }
+}
+
+static void xfer_n(const SkXfermode* xfer, uint64_t dst[], const SkPM4f src[], int count,
+                       const SkAlpha aa[]) {
+    SkXfermodeProc4f proc = xfer->getProc4f();
+    SkPM4f d;
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            Sk4f d4 = SkHalfToFloat_01(dst[i]);
+            d4.store(d.fVec);
+            Sk4f r4 = Sk4f::Load(proc(src[i], d).fVec);
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(r4, d4, aa[i]));
+        }
+    } else {
+        for (int i = 0; i < count; ++i) {
+            SkHalfToFloat_01(dst[i]).store(d.fVec);
+            Sk4f r4 = Sk4f::Load(proc(src[i], d).fVec);
+            dst[i] = SkFloatToHalf_01(r4);
+        }
+    }
+}
+
+const SkXfermode::F16Proc gProcs_General[] = { xfer_n, xfer_n, xfer_1, xfer_1 };
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static void clear(const SkXfermode*, uint64_t dst[], const SkPM4f*, int count, const SkAlpha aa[]) {
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            if (aa[i]) {
+                const Sk4f d4 = SkHalfToFloat_01(dst[i]);
+                dst[i] = SkFloatToHalf_01(d4 * Sk4f((255 - aa[i]) * 1.0f/255));
+            }
+        }
+    } else {
+        sk_memset64(dst, 0, count);
+    }
+}
+
+const SkXfermode::F16Proc gProcs_Clear[] = { clear, clear, clear, clear };
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static void src_1(const SkXfermode*, uint64_t dst[], const SkPM4f* src, int count,
+                  const SkAlpha aa[]) {
+    const Sk4f s4 = Sk4f::Load(src->fVec);
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            const Sk4f d4 = SkHalfToFloat_01(dst[i]);
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(s4, d4, aa[i]));
+        }
+    } else {
+        sk_memset64(dst, SkFloatToHalf_01(s4), count);
+    }
+}
+
+static void src_n(const SkXfermode*, uint64_t dst[], const SkPM4f src[], int count,
+                  const SkAlpha aa[]) {
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            const Sk4f s4 = Sk4f::Load(src[i].fVec);
+            const Sk4f d4 = SkHalfToFloat_01(dst[i]);
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(s4, d4, aa[i]));
+        }
+    } else {
+        for (int i = 0; i < count; ++i) {
+            const Sk4f s4 = Sk4f::Load(src[i].fVec);
+            dst[i] = SkFloatToHalf_01(s4);
+        }
+    }
+}
+
+const SkXfermode::F16Proc gProcs_Src[] = { src_n, src_n, src_1,  src_1 };
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static void dst(const SkXfermode*, uint64_t*, const SkPM4f*, int count, const SkAlpha[]) {}
+
+const SkXfermode::F16Proc gProcs_Dst[] = { dst, dst, dst, dst };
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static void srcover_1(const SkXfermode*, uint64_t dst[], const SkPM4f* src, int count,
+                      const SkAlpha aa[]) {
+    const Sk4f s4 = Sk4f::Load(src->fVec);
+    const Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
+    for (int i = 0; i < count; ++i) {
+        const Sk4f d4 = SkHalfToFloat_01(dst[i]);
+        const Sk4f r4 = s4 + d4 * dst_scale;
+        if (aa) {
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(r4, d4, aa[i]));
+        } else {
+            dst[i] = SkFloatToHalf_01(r4);
+        }
+    }
+}
+
+static void srcover_n(const SkXfermode*, uint64_t dst[], const SkPM4f src[], int count,
+                      const SkAlpha aa[]) {
+    for (int i = 0; i < count; ++i) {
+        const Sk4f s4 = Sk4f::Load(src[i].fVec);
+        const Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
+        const Sk4f d4 = SkHalfToFloat_01(dst[i]);
+        const Sk4f r4 = s4 + d4 * dst_scale;
+        if (aa) {
+            dst[i] = SkFloatToHalf_01(lerp_by_coverage(r4, d4, aa[i]));
+        } else {
+            dst[i] = SkFloatToHalf_01(r4);
+        }
+    }
+}
+
+const SkXfermode::F16Proc gProcs_SrcOver[] = { srcover_n, src_n, srcover_1, src_1 };
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+static SkXfermode::F16Proc find_proc(SkXfermode::Mode mode, uint32_t flags) {
+    SkASSERT(0 == (flags & ~3));
+    flags &= 3;
+
+    switch (mode) {
+        case SkXfermode::kClear_Mode:   return gProcs_Clear[flags];
+        case SkXfermode::kSrc_Mode:     return gProcs_Src[flags];
+        case SkXfermode::kDst_Mode:     return gProcs_Dst[flags];
+        case SkXfermode::kSrcOver_Mode: return gProcs_SrcOver[flags];
+        default:
+            break;
+    }
+    return gProcs_General[flags];
+}
+
+SkXfermode::F16Proc SkXfermode::onGetF16Proc(uint32_t flags) const {
+    SkASSERT(0 == (flags & ~3));
+    flags &= 3;
+
+    Mode mode;
+    return this->asMode(&mode) ? find_proc(mode, flags) : gProcs_General[flags];
+}
+
+SkXfermode::F16Proc SkXfermode::GetF16Proc(SkXfermode* xfer, uint32_t flags) {
+    return xfer ? xfer->onGetF16Proc(flags) : find_proc(SkXfermode::kSrcOver_Mode, flags);
+}