SkNx_shuffle

src/core/SkNx.h

Index: src/core/SkNx.h
diff --git a/src/core/SkNx.h b/src/core/SkNx.h
index ff94e0545870fa51bf9559b587fb615a3ca1e5bd..8d0ad720165b403b2adbdd8e35b49f1ab3c1c7f6 100644
--- a/src/core/SkNx.h
+++ b/src/core/SkNx.h
@@ -266,8 +266,23 @@ protected:
     T fVal;
 };
 
+// This default implementation can be specialized by ../opts/SkNx_foo.h
+// if there's a better platform-specific shuffle strategy.
+template <typename SkNx, int... Ix>
+inline SkNx SkNx_shuffle_impl(const SkNx& src) { return SkNx( src.template kth<Ix>()... ); }
+
+// This generic shuffle can be called on either SkNi or SkNf with either 1 or N indices:
+//     Sk4f(1,2,3,4) f;

[reed1, 2015/09/01 15:45:03]

do you mean Sk4f f(1,2,3,4); ?

Actually, I think it may be ever clearer to use letters, so as to clearly
distinguish between indices and values

e.g.

Sk4f f(a, b, c, d);

[mtklein_C, 2015/09/01 16:00:03]

Yep, done.

+//     SkNx_shuffle<0>(f);        // ~~~> Sk4f(1,1,1,1)
+//     SkNx_shuffle<2,1,0,3>(f);  // ~~~> Sk4f(3,2,1,4)
+template <int... Ix, typename SkNx>
+inline SkNx SkNx_shuffle(const SkNx& src) { return SkNx_shuffle_impl<SkNx, Ix...>(src); }
+
 }  // namespace
 
+
+
+
 // Include platform specific specializations if available.
 #ifndef SKNX_NO_SIMD
     #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2