1 files changed, 20 insertions, 0 deletions
diff --git a/src/math/ilogbf.c b/src/math/ilogbf.c
new file mode 100644
index 00000000..272cbdac
--- /dev/null
+++ b/src/math/ilogbf.c
@@ -0,0 +1,20 @@
+#include <limits.h>
+#include "libm.h"
+
+int ilogbf(float x)
+{
+	union fshape u = {x};
+	int e = u.bits>>23 & 0xff;
+
+	if (!e) {
+		u.bits <<= 9;
+		if (u.bits == 0)
+			return FP_ILOGB0;
+		/* subnormal x */
+		for (e = -0x7f; u.bits < (uint32_t)1<<31; e--, u.bits<<=1);
+		return e;
+	}
+	if (e == 0xff)
+		return u.bits<<9 ? FP_ILOGBNAN : INT_MAX;
+	return e - 0x7f;
+}