Refactor Sk2x<T> + Sk4x<T> into SkNf<N,T> and SkNi<N,T>

src/core/SkNx.h

Index: src/core/SkNx.h
diff --git a/src/core/SkNx.h b/src/core/SkNx.h
index 5926f36e858b9b40516f293eb9ef4b9343a5b162..e0a4aa56ecdb6adabc50d529e65264b60f4c593c 100644
--- a/src/core/SkNx.h
+++ b/src/core/SkNx.h
@@ -8,6 +8,178 @@
 #ifndef SkNx_DEFINED
 #define SkNx_DEFINED
 
-#define SKNX_NO_SIMDx  // Remove the x to disable SIMD in Sk2x and Sk4x.
+
+#define SKNX_NO_SIMDx  // Remove the x to disable SIMD for all SkNx types.
+
+
+#include "SkScalar.h"
+#include "SkTypes.h"
+#include <math.h>
+#define REQUIRE(x) static_assert(x, #x)
+
+// The default implementations of SkNi<N,T> and SkNf<N,T> just fall back on a pair of size N/2.
+template <int N, typename T>
+class SkNi {
+public:
+    // For now SkNi is a _very_ minimal sketch just to support comparison operators on SkNf.
+    SkNi() {}
+    SkNi(const SkNi<N/2, T>& lo, const SkNi<N/2, T>& hi) : fLo(lo), fHi(hi) {}
+    bool allTrue() const { return fLo.allTrue() && fHi.allTrue(); }
+    bool anyTrue() const { return fLo.anyTrue() || fHi.anyTrue(); }
+
+private:
+    REQUIRE(0 == (N & (N-1)));
+    SkNi<N/2, T> fLo, fHi;
+};
+
+template <int N, typename T>
+class SkNf {
+    static SkNi<N,int32_t> ToNi(float);
+    static SkNi<N,int64_t> ToNi(double);
+    typedef decltype(ToNi(T())) Ni;
+public:
+    SkNf() {}
+    explicit SkNf(T val)           : fLo(val),  fHi(val)      {}
+    static SkNf Load(const T vals[N]) {
+        return SkNf(SkNf<N/2,T>::Load(vals), SkNf<N/2,T>::Load(vals+N/2));
+    }
+
+    SkNf(T a, T b)                               : fLo(a),       fHi(b)       { REQUIRE(N==2); }
+    SkNf(T a, T b, T c, T d)                     : fLo(a,b),     fHi(c,d)     { REQUIRE(N==4); }
+    SkNf(T a, T b, T c, T d, T e, T f, T g, T h) : fLo(a,b,c,d), fHi(e,f,g,h) { REQUIRE(N==8); }
+
+    void store(T vals[N]) const {
+        fLo.store(vals);
+        fHi.store(vals+N/2);
+    }
+
+    SkNf operator + (const SkNf& o) const { return SkNf(fLo + o.fLo, fHi + o.fHi); }
+    SkNf operator - (const SkNf& o) const { return SkNf(fLo - o.fLo, fHi - o.fHi); }
+    SkNf operator * (const SkNf& o) const { return SkNf(fLo * o.fLo, fHi * o.fHi); }
+    SkNf operator / (const SkNf& o) const { return SkNf(fLo / o.fLo, fHi / o.fHi); }
+
+    Ni operator == (const SkNf& o) const { return Ni(fLo == o.fLo, fHi == o.fHi); }
+    Ni operator != (const SkNf& o) const { return Ni(fLo != o.fLo, fHi != o.fHi); }
+    Ni operator  < (const SkNf& o) const { return Ni(fLo  < o.fLo, fHi  < o.fHi); }
+    Ni operator  > (const SkNf& o) const { return Ni(fLo  > o.fLo, fHi  > o.fHi); }
+    Ni operator <= (const SkNf& o) const { return Ni(fLo <= o.fLo, fHi <= o.fHi); }
+    Ni operator >= (const SkNf& o) const { return Ni(fLo >= o.fLo, fHi >= o.fHi); }
+
+    static SkNf Min(const SkNf& l, const SkNf& r) {
+        return SkNf(SkNf<N/2,T>::Min(l.fLo, r.fLo), SkNf<N/2,T>::Min(l.fHi, r.fHi));
+    }
+    static SkNf Max(const SkNf& l, const SkNf& r) {
+        return SkNf(SkNf<N/2,T>::Max(l.fLo, r.fLo), SkNf<N/2,T>::Max(l.fHi, r.fHi));
+    }
+
+    SkNf  sqrt() const { return SkNf(fLo. sqrt(), fHi. sqrt()); }
+    SkNf rsqrt() const { return SkNf(fLo.rsqrt(), fHi.rsqrt()); }
+
+    SkNf       invert() const { return SkNf(fLo.      invert(), fHi.      invert()); }
+    SkNf approxInvert() const { return SkNf(fLo.approxInvert(), fHi.approxInvert()); }
+
+    T operator[] (int k) const {
+        SkASSERT(0 <= k && k < N);
+        return k < N/2 ? fLo[k] : fHi[k-N/2];
+    }
+
+private:
+    REQUIRE(0 == (N & (N-1)));
+    SkNf(const SkNf<N/2, T>& lo, const SkNf<N/2, T>& hi) : fLo(lo), fHi(hi) {}
+
+    SkNf<N/2, T> fLo, fHi;
+};
+
+
+// Bottom out the default implementation with scalars when nothing's been specialized.
+template <typename T>
+class SkNi<1,T> {
+public:
+    SkNi() {}
+    explicit SkNi(T val) : fVal(val) {}
+    bool allTrue() const { return (bool)fVal; }
+    bool anyTrue() const { return (bool)fVal; }
+
+private:
+    T fVal;
+};
+
+template <typename T>
+class SkNf<1,T> {
+    static SkNi<1,int32_t> ToNi(float);
+    static SkNi<1,int64_t> ToNi(double);
+    typedef decltype(ToNi(T())) Ni;
+public:
+    SkNf() {}
+    explicit SkNf(T val)           : fVal(val)     {}
+    static SkNf Load(const T vals[1]) { return SkNf(vals[0]); }
+
+    void store(T vals[1]) const { vals[0] = fVal; }
+
+    SkNf operator + (const SkNf& o) const { return SkNf(fVal + o.fVal); }
+    SkNf operator - (const SkNf& o) const { return SkNf(fVal - o.fVal); }
+    SkNf operator * (const SkNf& o) const { return SkNf(fVal * o.fVal); }
+    SkNf operator / (const SkNf& o) const { return SkNf(fVal / o.fVal); }
+
+    Ni operator == (const SkNf& o) const { return Ni(fVal == o.fVal); }
+    Ni operator != (const SkNf& o) const { return Ni(fVal != o.fVal); }
+    Ni operator  < (const SkNf& o) const { return Ni(fVal  < o.fVal); }
+    Ni operator  > (const SkNf& o) const { return Ni(fVal  > o.fVal); }
+    Ni operator <= (const SkNf& o) const { return Ni(fVal <= o.fVal); }
+    Ni operator >= (const SkNf& o) const { return Ni(fVal >= o.fVal); }
+
+    static SkNf Min(const SkNf& l, const SkNf& r) { return SkNf(SkTMin(l.fVal, r.fVal)); }
+    static SkNf Max(const SkNf& l, const SkNf& r) { return SkNf(SkTMax(l.fVal, r.fVal)); }
+
+    SkNf  sqrt() const { return SkNf(Sqrt(fVal));          }
+    SkNf rsqrt() const { return SkNf((T)1 / Sqrt(fVal)); }
+
+    SkNf       invert() const { return SkNf((T)1 / fVal); }
+    SkNf approxInvert() const { return this->invert();    }
+
+    T operator[] (int SkDEBUGCODE(k)) const {
+        SkASSERT(k == 0);
+        return fVal;
+    }
+
+private:
+    // We do double sqrts natively, or via floats for any other type.
+    template <typename U>
+    static U      Sqrt(U      val) { return (U) ::sqrtf((float)val); }
+    static double Sqrt(double val) { return     ::sqrt (       val); }
+
+    T fVal;
+};
+
+
+// Generic syntax sugar that should work equally well for all SkNi and SkNf implementations.
+template <typename SkNx> SkNx operator - (const SkNx& l) { return SkNx((decltype(l[0]))0) - l; }
+
+template <typename SkNx> SkNx& operator += (SkNx& l, const SkNx& r) { return (l = l + r); }
+template <typename SkNx> SkNx& operator -= (SkNx& l, const SkNx& r) { return (l = l - r); }
+template <typename SkNx> SkNx& operator *= (SkNx& l, const SkNx& r) { return (l = l * r); }
+template <typename SkNx> SkNx& operator /= (SkNx& l, const SkNx& r) { return (l = l / r); }
+
+
+// Include platform specific specializations if available.
+#ifndef SKNX_NO_SIMD
+    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+        #include "../opts/SkNx_sse.h"
+    #elif defined(SK_ARM_HAS_NEON)
+        #include "../opts/SkNx_neon.h"
+    #endif
+#endif
+
+#undef REQUIRE
+
+typedef SkNf<2,    float> Sk2f;
+typedef SkNf<2,   double> Sk2d;
+typedef SkNf<2, SkScalar> Sk2s;
+
+typedef SkNf<4,    float> Sk4f;
+typedef SkNf<4,   double> Sk4d;
+typedef SkNf<4, SkScalar> Sk4s;
+
+typedef SkNi<4, int32_t> Sk4i;
 
 #endif//SkNx_DEFINED