Sk2x

This adds an API, an SSE impl, a portable impl, and some tests for Sk2f/Sk2d/Sk2s.

BUG=skia:

Review URL: https://codereview.chromium.org/1025463002
diff --git a/tests/Sk2xTest.cpp b/tests/Sk2xTest.cpp
new file mode 100644
index 0000000..5f7bf68
--- /dev/null
+++ b/tests/Sk2xTest.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Test.h"
+#include "Sk2x.h"
+
+template <typename T>
+static bool nearly_eq(double eps, const Sk2x<T>& v, double x, double y) {
+    T vals[2];
+    v.store(vals);
+    return fabs(vals[0] - (T)x) <= eps && fabs(vals[1] - (T)y) <= eps;
+}
+
+template <typename T>
+static bool eq(const Sk2x<T>& v, double x, double y) { return nearly_eq(0, v, x, y); }
+
+template <typename T>
+static void test(skiatest::Reporter* r) {
+    // Constructors, assignment, etc.
+    Sk2x<T> a(4),
+            b = a,
+            c(a);
+    REPORTER_ASSERT(r, eq(a, 4, 4));
+    REPORTER_ASSERT(r, eq(b, 4, 4));
+    REPORTER_ASSERT(r, eq(c, 4, 4));
+
+    Sk2x<T> d(2, 5);
+    Sk2x<T> e;
+    e = d;
+    T vals[] = { 2, 5 };
+    Sk2x<T> f = Sk2x<T>::Load(vals);
+    REPORTER_ASSERT(r, eq(d, 2, 5));
+    REPORTER_ASSERT(r, eq(e, 2, 5));
+    REPORTER_ASSERT(r, eq(f, 2, 5));
+
+    a.store(vals);
+    REPORTER_ASSERT(r, vals[0] == 4 && vals[1] == 4);
+
+    // Math
+    REPORTER_ASSERT(r, eq(a.add(d),      6,   9));
+    REPORTER_ASSERT(r, eq(a.subtract(d), 2,  -1));
+    REPORTER_ASSERT(r, eq(a.multiply(d), 8,  20));
+
+    REPORTER_ASSERT(r, nearly_eq(0.001, a.rsqrt(), 0.5, 0.5));
+    REPORTER_ASSERT(r, eq(a.sqrt(), 2, 2));
+
+    REPORTER_ASSERT(r, eq(Sk2x<T>::Min(a, d), 2, 4));
+    REPORTER_ASSERT(r, eq(Sk2x<T>::Max(a, d), 4, 5));
+}
+
+DEF_TEST(Sk2f, r) { test< float>(r); }
+DEF_TEST(Sk2d, r) { test<double>(r); }