xref: /illumos-gate/usr/src/lib/libm/common/m9x/fmaxl.c (revision eb9a1df2aeb866bf1de4494433b6d7e5fa07b3ae)
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 fmaxl = __fmaxl
31 
32 #include "libm.h"	/* for isgreaterequal macro */
33 
34 long double
35 __fmaxl(long double x, long double y) {
36 	union {
37 #if defined(__sparc)
38 		unsigned i[4];
39 #elif defined(__x86)
40 		unsigned i[3];
41 #else
42 #error Unknown architecture
43 #endif
44 		long double ld;
45 	} xx, yy;
46 	unsigned s;
47 
48 	/* if y is nan, replace it by x */
49 	if (y != y)
50 		y = x;
51 
52 	/* if x is nan, replace it by y */
53 	if (x != x)
54 		x = y;
55 
56 	/* At this point, x and y are either both numeric, or both NaN */
57 	if (!isnan(x) && !isgreaterequal(x, y))
58 		x = y;
59 
60 	/*
61 	 * clear the sign of the result if either x or y has its sign clear
62 	 */
63 	xx.ld = x;
64 	yy.ld = y;
65 #if defined(__sparc)
66 	s = ~(xx.i[0] & yy.i[0]) & 0x80000000;
67 	xx.i[0] &= ~s;
68 #elif defined(__x86)
69 	s = ~(xx.i[2] & yy.i[2]) & 0x8000;
70 	xx.i[2] &= ~s;
71 #else
72 #error Unknown architecture
73 #endif
74 
75 	return (xx.ld);
76 }
77