xref: /titanic_44/usr/src/lib/libm/common/m9x/llroundf.c (revision a05fd0c9b9aa46cf66ddea7617e56facdf1f4aaf)
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 llroundf = __llroundf
32 #if defined(__sparcv9) || defined(__amd64)
33 #pragma weak lroundf = __llroundf
34 #pragma weak __lroundf = __llroundf
35 #endif
36 #endif
37 
38 #include "libm.h"
39 
40 long long
41 llroundf(float x) {
42 	union {
43 		unsigned i;
44 		float f;
45 	} xx;
46 	unsigned hx, sx, i;
47 
48 	xx.f = x;
49 	hx = xx.i & ~0x80000000;
50 	sx = xx.i & 0x80000000;
51 
52 	if (hx < 0x4b000000) { /* |x| < 2^23 */
53 		/* handle |x| < 1 */
54 		if (hx < 0x3f800000) {
55 			if (hx >= 0x3f000000)
56 				return (sx ? -1LL : 1LL);
57 			return (0LL);
58 		}
59 
60 		/* round x at the integer bit */
61 		i = 1 << (0x95 - (hx >> 23));
62 		xx.i = (xx.i + i) & ~((i << 1) - 1);
63 
64 		/*
65 		 * on LP32 architectures, we can just convert x to a 32-bit
66 		 * integer and sign-extend it
67 		 */
68 		return ((long) xx.f);
69 	}
70 
71 	/* now x is nan, inf, or integral */
72 	return ((long long) x);
73 }
74