1 files changed, 13 insertions, 0 deletions
diff --git a/src/math/__signbit.c b/src/math/__signbit.c
new file mode 100644
index 00000000..ffe717ce
--- /dev/null
+++ b/src/math/__signbit.c
@@ -0,0 +1,13 @@
+#include "libm.h"
+
+// FIXME: macro
+int __signbit(double x)
+{
+	union {
+		double d;
+		uint64_t i;
+	} y = { x };
+	return y.i>>63;
+}
+
+