xref: /titanic_51/usr/src/lib/libm/common/m9x/frexpf.c (revision 60bf7f6fe2a9d65f5b54de946358dfd8ff1e46e0)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24  */
25 /*
26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 #if defined(ELFOBJ)
31 #pragma weak frexpf = __frexpf
32 #endif
33 
34 #include "libm.h"
35 
36 float
37 __frexpf(float x, int *exp) {
38 	union {
39 		unsigned i;
40 		float f;
41 	} xx;
42 	unsigned hx;
43 	int e;
44 
45 	xx.f = x;
46 	hx = xx.i & ~0x80000000;
47 
48 	if (hx >= 0x7f800000) { /* x is infinite or NaN */
49 		*exp = 0;
50 		return (x);
51 	}
52 
53 	e = 0;
54 	if (hx < 0x00800000) { /* x is subnormal or zero */
55 		if (hx == 0) {
56 			*exp = 0;
57 			return (x);
58 		}
59 
60 		/* normalize x by regarding it as an integer */
61 		xx.f = (int) xx.i < 0 ? -(int) hx : (int) hx;
62 		hx = xx.i & ~0x80000000;
63 		e = -149;
64 	}
65 
66 	/* now xx.f is normal */
67 	xx.i = (xx.i & ~0x7f800000) | 0x3f000000;
68 	*exp = e + (hx >> 23) - 0x7e;
69 	return (xx.f);
70 }
71