Sk4px

src/core/Sk4px.h

Index: src/core/Sk4px.h
diff --git a/src/core/Sk4px.h b/src/core/Sk4px.h
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+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef Sk4px_DEFINED
+#define Sk4px_DEFINED
+
+#include "SkNx.h"
+#include "SkColor.h"
+
+// 1, 2 or 4 SkPMColors, generally vectorized.
+class Sk4px : public Sk16b {
+public:
+    Sk4px(SkPMColor);  // Duplicate 4x.
+    Sk4px(const Sk16b& v) : Sk16b(v) {}
+
+    // When loading or storing fewer than 4 SkPMColors, we use the low lanes.
+    static Sk4px Load4(const SkPMColor[4]);
+    static Sk4px Load2(const SkPMColor[2]);
+    static Sk4px Load1(const SkPMColor[1]);
+
+    void store4(SkPMColor[4]) const;
+    void store2(SkPMColor[2]) const;
+    void store1(SkPMColor[1]) const;
+
+    // 1, 2, or 4 SkPMColors with 16-bit components.
+    // This is most useful as the result of a multiply, e.g. from mulWiden().
+    class Wide : public Sk16h {
+    public:
+        Wide(const Sk16h& v) : Sk16h(v) {}
+
+        // Pack the top byte of each component back down into 4 SkPMColors.
+        Sk4px addNarrowHi(const Sk16h&) const;
+    private:
+        typedef Sk16h INHERITED;
+    };
+
+    Wide widenLo() const;               // ARGB -> 0A 0R 0G 0B
+    Wide widenHi() const;               // ARGB -> A0 R0 G0 B0
+    Wide mulWiden(const Sk16b&) const;  // 8-bit x 8-bit -> 16-bit components.
+
+    // A generic driver that maps fn over a src array into a dst array.
+    // fn should take an Sk4px (4 src pixels) and return an Sk4px (4 dst pixels).
+    template <typename Fn>
+    static void MapSrc(int count, SkPMColor* dst, const SkPMColor* src, Fn fn) {
+        // This looks a bit odd, but it helps loop-invariant hoisting across different calls to fn.
+        // Basically, we need to make sure we keep things inside a single loop.
+        while (count > 0) {
+            if (count >= 8) {
+                Sk4px dst0 = fn(Load4(src+0)),
+                      dst4 = fn(Load4(src+4));
+                dst0.store4(dst+0);
+                dst4.store4(dst+4);
+                dst += 8; src += 8; count -= 8;
+                continue;  // Keep our stride at 8 pixels as long as possible.
+            }
+            SkASSERT(count <= 7);
+            if (count >= 4) {
+                fn(Load4(src)).store4(dst);
+                dst += 4; src += 4; count -= 4;
+            }
+            if (count >= 2) {
+                fn(Load2(src)).store2(dst);
+                dst += 2; src += 2; count -= 2;
+            }
+            if (count >= 1) {
+                fn(Load1(src)).store1(dst);
+            }
+            break;
+        }
+    }
+
+private:
+    typedef Sk16b INHERITED;
+};
+
+#ifdef SKNX_NO_SIMD
+    #include "../opts/Sk4px_none.h"
+#else
+    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+        #include "../opts/Sk4px_SSE2.h"
+    #elif defined(SK_ARM_HAS_NEON)
+        #include "../opts/Sk4px_NEON.h"
+    #else
+        #include "../opts/Sk4px_none.h"
+    #endif
+#endif
+
+#endif//Sk4px_DEFINED