xref: /illumos-gate/usr/src/lib/libm/common/m9x/fmin.c (revision 45ede40b2394db7967e59f19288fae9b62efd4aa)
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 fmin = __fmin
31 
32 /*
33  * fmin(x,y) returns the smaller of x and y.  If just one of the
34  * arguments is NaN, fmin returns the other argument.  If both
35  * arguments are NaN, fmin returns NaN.
36  *
37  * See fmaxf.c for a discussion of implementation trade-offs.
38  */
39 
40 #include "libm.h"	/* for islessequal macro */
41 
42 #include "fenv_inlines.h"
43 #include <stdio.h>
44 #include <sys/isa_defs.h>
45 
46 double
47 __fmin(double x, double y) {
48 	union {
49 		unsigned i[2];
50 		double d;
51 	} xx, yy;
52 	unsigned s;
53 
54 	/* if y is nan, replace it by x */
55 	if (y != y)
56 		y = x;
57 
58 	/* if x is nan, replace it by y */
59 	if (x != x)
60 		x = y;
61 
62 	/* At this point, x and y are either both numeric, or both NaN */
63 	if (!isnan(x) && !islessequal(x, y))
64 		x = y;
65 
66 	/*
67 	 * set the sign of the result if either x or y has its sign set
68 	 */
69 	xx.d = x;
70 	yy.d = y;
71 #if defined(_BIG_ENDIAN)
72 	s = (xx.i[0] | yy.i[0]) & 0x80000000;
73 	xx.i[0] |= s;
74 #else
75 	s = (xx.i[1] | yy.i[1]) & 0x80000000;
76 	xx.i[1] |= s;
77 #endif
78 
79 	return (xx.d);
80 }
81