import newlib-2000-02-17 snapshot

1 files changed, 42 insertions, 0 deletions

diff --git a/newlib/libm/common/s_logb.c b/newlib/libm/common/s_logb.c
new file mode 100644
index 000000000..dbddd1994
--- /dev/null
+++ b/newlib/libm/common/s_logb.c
@@ -0,0 +1,42 @@
+
+/* @(#)s_logb.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, 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"
+
+#ifndef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+	double logb(double x)
+#else
+	double logb(x)
+	double x;
+#endif
+{
+	__int32_t lx,ix;
+	EXTRACT_WORDS(ix,lx,x);
+	ix &= 0x7fffffff;			/* high |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); 
+}
+
+#endif /* _DOUBLE_IS_32BITS */