xref: /titanic_41/usr/src/lib/libm/common/m9x/fminf.c (revision fc7a376ec44146b66b5d6bc4ed92ba311773e202)
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 fminf = __fminf
31 
32 #include "libm.h"	/* for islessequal macro */
33 
34 float
35 __fminf(float x, float y) {
36 	/*
37 	 * On SPARC v8plus/v9, this could be implemented as follows
38 	 * (assuming %f0 = x, %f1 = y, return value left in %f0):
39 	 *
40 	 * fcmps	%fcc0,%f1,%f1
41 	 * fmovsu	%fcc0,%f0,%f1
42 	 * fcmps	%fcc0,%f0,%f1
43 	 * fmovsug	%fcc0,%f1,%f0
44 	 * st		%f0,[x]
45 	 * st		%f1,[y]
46 	 * ld		[x],%l0
47 	 * ld		[y],%l1
48 	 * or		%l0,%l1,%l2
49 	 * sethi	%hi(0x80000000),%l3
50 	 * and		%l3,%l2,%l2
51 	 * or		%l0,%l2,%l0
52 	 * st		%l0,[x]
53 	 * ld		[x],%f0
54 	 *
55 	 * If VIS instructions are available, use this code instead:
56 	 *
57 	 * fcmps	%fcc0,%f1,%f1
58 	 * fmovsu	%fcc0,%f0,%f1
59 	 * fcmps	%fcc0,%f0,%f1
60 	 * fmovsug	%fcc0,%f1,%f0
61 	 * fors		%f0,%f1,%f2
62 	 * fzeros	%f3
63 	 * fnegs	%f3,%f3
64 	 * fands	%f3,%f2,%f2
65 	 * fors		%f0,%f2,%f0
66 	 *
67 	 * If VIS 3.0 instructions are available, use this:
68 	 *
69 	 * flcmps	%fcc0,%f0,%f1
70 	 * fmovsge	%fcc0,%f1,%f0	! move if %fcc0 is 0 or 2
71 	 */
72 
73 	union {
74 		unsigned i;
75 		float f;
76 	} xx, yy;
77 	unsigned s;
78 
79 	/* if y is nan, replace it by x */
80 	if (y != y)
81 		y = x;
82 
83 	/* if x is nan, replace it by y */
84 	if (x != x)
85 		x = y;
86 
87 	/* At this point, x and y are either both numeric, or both NaN */
88 	if (!isnan(x) && !islessequal(x, y))
89 		x = y;
90 
91 	/*
92 	 * set the sign of the result if either x or y has its sign set
93 	 */
94 	xx.f = x;
95 	yy.f = y;
96 	s = (xx.i | yy.i) & 0x80000000;
97 	xx.i |= s;
98 
99 	return (xx.f);
100 }
101