xref: /illumos-gate/usr/src/lib/libm/common/m9x/lroundf.c (revision ddc0e0b5)
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 #pragma weak __lroundf = lroundf
31 
32 #include <sys/isa_defs.h>	/* _ILP32 */
33 #include "libm.h"
34 
35 #if defined(_ILP32)
36 long
lroundf(float x)37 lroundf(float x) {
38 	union {
39 		unsigned i;
40 		float f;
41 	} xx;
42 	unsigned hx, sx, i;
43 
44 	xx.f = x;
45 	hx = xx.i & ~0x80000000;
46 	sx = xx.i & 0x80000000;
47 	if (hx < 0x4b000000) {		/* |x| < 2^23 */
48 		if (hx < 0x3f800000) {		/* |x| < 1 */
49 			if (hx >= 0x3f000000)
50 				return (sx ? -1L : 1L);
51 			return (0L);
52 		}
53 
54 		/* round x at the integer bit */
55 		i = 1 << (0x95 - (hx >> 23));
56 		xx.i = (xx.i + i) & ~((i << 1) - 1);
57 		return ((long) xx.f);
58 	}
59 
60 	/* now x is nan, inf, or integral */
61 	return ((long) x);
62 }
63 #else
64 #error Unsupported architecture
65 #endif	/* defined(_ILP32) */
66