sync code with last improvements from OpenBSD

regress/lib/libc/modf/modf_test.c

@@ -1,35 +1,67 @@
-/* Public domain, 2014, Tobias Ulmer <tobiasu@tmux.org> */
+/*	$OpenBSD: modf_test.c,v 1.2 2023/08/13 06:57:04 miod Exp $	*/
+
+#include <assert.h>
+#include <math.h>
 
 /* Test for bug introduced in 4.4BSD modf() on sparc */
-
-#include <math.h>
+/* Public domain, 2014, Tobias Ulmer <tobiasu@tmux.org> */
 
 #define BIGFLOAT (5e15) /* Number large enough to trigger the "big" case */
 
-int
-main(void)
+void
+modf_sparc(void)
 {
 	double f, i;
 
 	f = modf(BIGFLOAT, &i);
-	if (i != BIGFLOAT)
-		return 1;
-	if (f != 0.0)
-		return 1;
+	assert(i == BIGFLOAT);
+	assert(f == 0.0);
 
 	/* Repeat, maybe we were lucky */
 	f = modf(BIGFLOAT, &i);
-	if (i != BIGFLOAT)
-		return 1;
-	if (f != 0.0)
-		return 1;
+	assert(i == BIGFLOAT);
+	assert(f == 0.0);
 
 	/* With negative number, for good measure */
 	f = modf(-BIGFLOAT, &i);
-	if (i != -BIGFLOAT)
-		return 1;
-	if (f != 0.0)
-		return 1;
-
-	return 0;
+	assert(i == -BIGFLOAT);
+	assert(f == 0.0);
+}
+
+/* Test for modf() behaviour on Inf and Nan */
+/* Written by Willemijn Coene.  Public domain */
+
+void
+modf_infnan(void)
+{
+	double f, i;
+
+	f = modf(__builtin_inf(), &i);
+	assert(isinf(i));
+	assert(signbit(i) == 0);
+	assert(f == 0.0);
+
+	f = modf(-__builtin_inf(), &i);
+	assert(isinf(i));
+	assert(signbit(i) != 0);
+	assert(f == -0.0);
+
+	f = modf(NAN, &i);
+	assert(isnan(i));
+	assert(signbit(i) == 0);
+	assert(isnan(f));
+	assert(signbit(f) == 0);
+
+	f = modf(-NAN, &i);
+	assert(isnan(i));
+	assert(signbit(i) != 0);
+	assert(isnan(f));
+	assert(signbit(f) != 0);
+}
+
+int
+main(void)
+{
+	modf_sparc();
+	modf_infnan();
 }