1 files changed, 66 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/LD/log1pl.c b/usr/src/lib/libm/common/LD/log1pl.c
new file mode 100644
index 0000000000..97dc4910c4
--- /dev/null
+++ b/usr/src/lib/libm/common/LD/log1pl.c
@@ -0,0 +1,66 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
+ */
+/*
+ * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#if defined(ELFOBJ)
+#pragma weak log1pl = __log1pl
+#endif
+
+/*
+ * log1pl(x)
+ * Kahan's trick based on log(1+x)/x being a slow varying function.
+ */
+
+#include "libm.h"
+
+#if defined(__x86)
+#define	__swapRD	__swap87RD
+#endif
+extern enum fp_direction_type __swapRD(enum fp_direction_type);
+
+long double
+log1pl(long double x) {
+	long double y;
+	enum fp_direction_type rd;
+
+	if (x != x)
+		return (x + x);
+	if (x < -1.L)
+		return (logl(x));
+	rd = __swapRD(fp_nearest);
+	y = 1.L + x;
+	if (y != 1.L) {
+		if (y == x)
+			x = logl(x);
+		else
+			x *= logl(y) / (y - 1.L);
+	}
+	if (rd != fp_nearest)
+		(void) __swapRD(rd);
+	return (x);
+}