1 files changed, 120 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/C/scalbn.c b/usr/src/lib/libm/common/C/scalbn.c
new file mode 100644
index 0000000000..1d344b8cbe
--- /dev/null
+++ b/usr/src/lib/libm/common/C/scalbn.c
@@ -0,0 +1,120 @@
+/*
+ * 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.
+ */
+
+#pragma weak scalbn = __scalbn
+
+#include "libm.h"
+
+static const double
+	one	= 1.0,
+	huge	= 1.0e300,
+	tiny	= 1.0e-300,
+	twom54	= 5.5511151231257827021181583404541015625e-17;
+
+#if defined(USE_FPSCALE) || defined(__x86)
+static const double two52 = 4503599627370496.0;
+#else
+/*
+ * Normalize non-zero subnormal x and return biased exponent of x in [-51,0]
+ */
+static int
+ilogb_biased(unsigned *px) {
+	int s = 52;
+	unsigned v = px[HIWORD] & ~0x80000000, w = px[LOWORD], t = v;
+
+	if (t)
+		s -= 32;
+	else
+		t = w;
+	if (t & 0xffff0000)
+		s -= 16, t >>= 16;
+	if (t & 0xff00)
+		s -= 8, t >>= 8;
+	if (t & 0xf0)
+		s -= 4, t >>= 4;
+	t <<= 1;
+	s -= (0xffffaa50 >> t) & 0x3;
+	if (s < 32) {
+		v = (v << s) | w >> (32 - s);
+		w <<= s;
+	} else {
+		v = w << (s - 32);
+		w = 0;
+	}
+	px[HIWORD] = (px[HIWORD] & 0x80000000) | v;
+	px[LOWORD] = w;
+	return (1 - s);
+}
+#endif	/* defined(USE_FPSCALE) */
+
+double
+scalbn(double x, int n) {
+	int	*px, ix, hx, k;
+
+	px = (int *)&x;
+	ix = px[HIWORD];
+	hx = ix & ~0x80000000;
+	k = hx >> 20;
+
+	if (k == 0x7ff)	/* x is inf or NaN */
+		return (x * one);
+
+	if (k == 0) {
+		if ((hx | px[LOWORD]) == 0 || n == 0)
+			return (x);
+#if defined(USE_FPSCALE) || defined(__x86)
+		x *= two52;
+		ix = px[HIWORD];
+		k = ((ix & ~0x80000000) >> 20) - 52;
+#else
+		k = ilogb_biased((unsigned *)px);
+		ix = px[HIWORD];
+#endif
+		/* now k is in the range -51..0 */
+		k += n;
+		if (k > n)	/* integer overflow occurred */
+			k = -100;
+	} else {
+		/* k is in the range 1..1023 */
+		k += n;
+		if (k < n)	/* integer overflow occurred */
+			k = 0x7ff;
+	}
+
+	if (k > 0x7fe)
+		return (huge * ((ix < 0)? -huge : huge));
+	if (k < 1) {
+		if (k <= -54)
+			return (tiny * ((ix < 0)? -tiny : tiny));
+		k += 54;
+		px[HIWORD] = (ix & ~0x7ff00000) | (k << 20);
+		return (x * twom54);
+	}
+	px[HIWORD] = (ix & ~0x7ff00000) | (k << 20);
+	return (x);
+}