693 Opensource replacement of sunwlibm

Reviewed by: Igor Kozhukhov ikozhukhov@gmail.com
Reviewed by: Keith M Wesolowski <keith.wesolowski@joyent.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Approved by: Dan McDonald <danmcd@omniti.com>

1 files changed, 103 insertions, 0 deletions

diff --git a/usr/src/lib/libm/common/m9x/frexp.c b/usr/src/lib/libm/common/m9x/frexp.c
new file mode 100644
index 0000000000..d13ebd907f
--- /dev/null
+++ b/usr/src/lib/libm/common/m9x/frexp.c
@@ -0,0 +1,103 @@
+/*
+ * 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 frexp = __frexp
+#endif
+
+/*
+ * frexp(x, exp) returns the normalized significand of x and sets
+ * *exp so that x = r*2^(*exp) where r is the return value.  If x
+ * is finite and nonzero, 1/2 <= |r| < 1.
+ *
+ * If x is zero, infinite or NaN, frexp returns x and sets *exp = 0.
+ * (The relevant standards do not specify *exp when x is infinite or
+ * NaN, but this code sets it anyway.)
+ *
+ * If x is a signaling NaN, this code returns x without attempting
+ * to raise the invalid operation exception.  If x is subnormal,
+ * this code treats it as nonzero regardless of nonstandard mode.
+ */
+
+#include "libm.h"
+
+double
+__frexp(double x, int *exp) {
+	union {
+		unsigned i[2];
+		double d;
+	} xx, yy;
+	double t;
+	unsigned hx;
+	int e;
+
+	xx.d = x;
+	hx = xx.i[HIWORD] & ~0x80000000;
+
+	if (hx >= 0x7ff00000) { /* x is infinite or NaN */
+		*exp = 0;
+		return (x);
+	}
+
+	e = 0;
+	if (hx < 0x00100000) { /* x is subnormal or zero */
+		if ((hx | xx.i[LOWORD]) == 0) {
+			*exp = 0;
+			return (x);
+		}
+
+		/*
+		 * normalize x by regarding it as an integer
+		 *
+		 * Here we use 32-bit integer arithmetic to avoid trapping
+		 * or emulating 64-bit arithmetic.  If 64-bit arithmetic is
+		 * available (e.g., in SPARC V9), do this instead:
+		 *
+		 *  long lx = ((long) hx << 32) | xx.i[LOWORD];
+		 *  xx.d = (xx.i[HIWORD] < 0)? -lx : lx;
+		 *
+		 * If subnormal arithmetic doesn't trap, just multiply x by
+		 * a power of two.
+		 */
+		yy.i[HIWORD] = 0x43300000 | hx;
+		yy.i[LOWORD] = xx.i[LOWORD];
+		t = yy.d;
+		yy.i[HIWORD] = 0x43300000;
+		yy.i[LOWORD] = 0;
+		t -= yy.d; /* t = |x| scaled */
+		xx.d = ((int)xx.i[HIWORD] < 0)? -t : t;
+		hx = xx.i[HIWORD] & ~0x80000000;
+		e = -1074;
+	}
+
+	/* now xx.d is normal */
+	xx.i[HIWORD] = (xx.i[HIWORD] & ~0x7ff00000) | 0x3fe00000;
+	*exp = e + (hx >> 20) - 0x3fe;
+	return (xx.d);
+}