1 files changed, 87 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/R/logbf.c b/usr/src/lib/libm/common/R/logbf.c
new file mode 100644
index 0000000000..bf6851ef68
--- /dev/null
+++ b/usr/src/lib/libm/common/R/logbf.c
@@ -0,0 +1,87 @@
+/*
+ * 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 logbf = __logbf
+#endif
+
+#include "libm.h"
+#include "xpg6.h"	/* __xpg6 */
+#define	_C99SUSv3_logb	_C99SUSv3_logb_subnormal_is_like_ilogb
+
+#if defined(USE_FPSCALE) || defined(__x86)
+static const float two25 = 33554432.0F;
+#else
+/*
+ * v: a non-zero subnormal |x|
+ */
+static int
+ilogbf_subnormal(unsigned v) {
+	int r = -126 - 23;
+
+	if (v & 0xffff0000)
+		r += 16, v >>= 16;
+	if (v & 0xff00)
+		r += 8, v >>= 8;
+	if (v & 0xf0)
+		r += 4, v >>= 4;
+	v <<= 1;
+	return (r + ((0xffffaa50 >> v) & 0x3));
+}
+#endif	/* defined(USE_FPSCALE) */
+
+static float
+raise_division(float t) {
+#pragma STDC FENV_ACCESS ON
+	static const float zero = 0.0F;
+	return (t / zero);
+}
+
+float
+logbf(float x) {
+	int k = *((int *) &x) & ~0x80000000;
+
+	if (k < 0x00800000) {
+		if (k == 0)
+			return (raise_division(-1.0F));
+		else if ((__xpg6 & _C99SUSv3_logb) != 0) {
+#if defined(USE_FPSCALE) || defined(__x86)
+			x *= two25;
+			return ((float) (((*((int *) &x) & 0x7f800000) >> 23) -
+				152));
+#else
+			return ((float) ilogbf_subnormal(k));
+#endif
+		} else
+			return (-126.F);
+	} else if (k < 0x7f800000)
+		return ((float) ((k >> 23) - 127));
+	else
+		return (x * x);
+}