1 files changed, 11 insertions, 0 deletions
diff --git a/lib/libm/__signbit.c b/lib/libm/__signbit.c
new file mode 100644
index 00000000..5d145b63
--- /dev/null
+++ b/lib/libm/__signbit.c
@@ -0,0 +1,11 @@
+#include "libm.h"
+
+// FIXME: macro in math.h
+int __signbit(double x)
+{
+	union {
+		double d;
+		uint64_t i;
+	} y = { x };
+	return y.i >> 63;
+}