1 files changed, 38 insertions, 0 deletions
diff --git a/libm/src/s_logb.c b/libm/src/s_logb.c
new file mode 100644
index 0000000..ec3d5ca
--- /dev/null
+++ b/libm/src/s_logb.c
@@ -0,0 +1,38 @@
+
+/* @(#)s_logb.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * double logb(x)
+ * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
+ * Use ilogb instead.
+ */
+
+#include "fdlibm.h"
+
+#ifdef __STDC__
+	double logb(double x)
+#else
+	double logb(x)
+	double x;
+#endif
+{
+	int lx,ix;
+	ix = (__HI(x))&0x7fffffff;	/* high |x| */
+	lx = __LO(x);			/* low x */
+	if((ix|lx)==0) return -1.0/fabs(x);
+	if(ix>=0x7ff00000) return x*x;
+	if((ix>>=20)==0) 			/* IEEE 754 logb */
+		return -1022.0; 
+	else
+		return (double) (ix-1023); 
+}