usr: libc: Add math.h + musl math impl portexpt

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/fmax.c b/lib/libc/src/musl-math/fmax.c
new file mode 100644
index 0000000..94f0caa
--- /dev/null
+++ b/lib/libc/src/musl-math/fmax.c
@@ -0,0 +1,13 @@
+#include <math.h>
+
+double fmax(double x, double y)
+{
+	if (isnan(x))
+		return y;
+	if (isnan(y))
+		return x;
+	/* handle signed zeros, see C99 Annex F.9.9.2 */
+	if (signbit(x) != signbit(y))
+		return signbit(x) ? y : x;
+	return x < y ? y : x;
+}