xref: /titanic_41/usr/src/lib/libm/common/m9x/lroundf.c (revision 018207534e5d18020ddb86fea48c6d68c7a2626d)
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 lroundf = __lroundf
32 #endif
33 
34 #include <sys/isa_defs.h>	/* _ILP32 */
35 #include "libm.h"
36 
37 #if defined(_ILP32)
38 long
39 lroundf(float x) {
40 	union {
41 		unsigned i;
42 		float f;
43 	} xx;
44 	unsigned hx, sx, i;
45 
46 	xx.f = x;
47 	hx = xx.i & ~0x80000000;
48 	sx = xx.i & 0x80000000;
49 	if (hx < 0x4b000000) {		/* |x| < 2^23 */
50 		if (hx < 0x3f800000) {		/* |x| < 1 */
51 			if (hx >= 0x3f000000)
52 				return (sx ? -1L : 1L);
53 			return (0L);
54 		}
55 
56 		/* round x at the integer bit */
57 		i = 1 << (0x95 - (hx >> 23));
58 		xx.i = (xx.i + i) & ~((i << 1) - 1);
59 		return ((long) xx.f);
60 	}
61 
62 	/* now x is nan, inf, or integral */
63 	return ((long) x);
64 }
65 #else
66 #error Unsupported architecture
67 #endif	/* defined(_ILP32) */
68