Isolated emscripten in new lib

lib/emscripten/emtests/test_float_builtins.c

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2017 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+
+#include <math.h>
+#include <stdio.h>
+
+// Prints the float/double/long double versions of the given function
+// e.g.: TEST(fmax) prints fmaxf : fmax : fmaxl
+#define TEST(func)                    \
+    printf("%f : %f : %Lf\n",         \
+        __builtin_##func##f(f1, f2),  \
+        __builtin_##func(d1, d2),     \
+        __builtin_##func##l(l1, l2));
+
+int test_builtins() {
+    float f1 = 0.1234f;
+    float f2 = 0.5678f;
+    double d1 = 1.0101;
+    double d2 = 0.10101;
+    long double l1 = 12.0123L;
+    long double l2 = 21.3201L;
+    TEST(fmax)
+    TEST(fmin)
+    TEST(fmod)
+    return 0;
+}
+
+void test_exp_log(double x) {
+    double a = exp2(x);
+    double b = log10(x);
+    float c = log10f(x);
+    double d = acos(x);
+    printf("%f : %f : %f : %d\n", a, b, c, isnan(d));
+}
+
+int main() {
+    puts("***start***");
+    test_builtins();
+    test_exp_log(1234.5678);
+    puts("***end***");
+    return 0;
+}