Move float<->byte conversions into Sk4f.

src/core/SkNx.h

 /*
  * 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 SkNx_DEFINED
 #define SkNx_DEFINED
 
@@ skipping 74 matching lines @@
 class SkNf {
     static int32_t MyNi(float);
     static int64_t MyNi(double);
     typedef decltype(MyNi(T())) I;
 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));
     }
+    // FromBytes() and toBytes() specializations may assume their argument is N-byte aligned.
+    // E.g. Sk4f::FromBytes() may assume it's reading from a 4-byte-aligned pointer.
+    // Converts [0,255] bytes to [0.0, 255.0] floats.
+    static SkNf FromBytes(const uint8_t bytes[N]) {
+        return SkNf(SkNf<N/2,T>::FromBytes(bytes), SkNf<N/2,T>::FromBytes(bytes+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);
     }
+    // Please see note on FromBytes().
+    // Truncates [0.0,256.0) floats to [0,255] bytes.  Other inputs are unspecified.
+    void toBytes(uint8_t bytes[N]) const {
+        fLo.toBytes(bytes);
+        fHi.toBytes(bytes+N/2);
+    }
 
     SkNi<N,I> castTrunc() const { return SkNi<N,I>(fLo.castTrunc(), fHi.castTrunc()); }
 
     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); }
 
     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); }
@@ skipping 80 matching lines @@
 
 template <typename T>
 class SkNf<1,T> {
     static int32_t MyNi(float);
     static int64_t MyNi(double);
     typedef decltype(MyNi(T())) I;
 public:
     SkNf() {}
     explicit SkNf(T val) : fVal(val) {}
     static SkNf Load(const T vals[1]) { return SkNf(vals[0]); }
+    static SkNf FromBytes(const uint8_t bytes[1]) { return SkNf((T)bytes[0]); }
 
     void store(T vals[1]) const { vals[0] = fVal; }
+    void toBytes(uint8_t bytes[1]) const { bytes[0] = (uint8_t)(fVal); }
 
     SkNi<1,I> castTrunc() const { return SkNi<1,I>(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); }
 
     SkNf operator == (const SkNf& o) const { return SkNf(fVal == o.fVal); }
     SkNf operator != (const SkNf& o) const { return SkNf(fVal != o.fVal); }
@@ skipping 60 matching lines @@
 typedef SkNi<4,  uint16_t> Sk4h;
 typedef SkNi<8,  uint16_t> Sk8h;
 typedef SkNi<16, uint16_t> Sk16h;
 
 typedef SkNi<16, uint8_t> Sk16b;
 
 typedef SkNi<4,  int32_t> Sk4i;
 typedef SkNi<4, uint32_t> Sk4u;
 
 #endif//SkNx_DEFINED