xref: /titanic_41/usr/src/lib/libm/common/m9x/fdimf.c (revision bb6fd8f9750a0c1d46a75c5bcc91952d3709334b)
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 fdimf = __fdimf
31 
32 #include "libm.h"	/* for islessequal macro */
33 
34 float
35 __fdimf(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,%f0,%f1
41 	 * st		%g0,[scratch]	! use fzero instead of st/ld
42 	 * ld		[scratch],%f2	! if VIS is available
43 	 * fnegs	%f2,%f3
44 	 * fmovsle	%fcc0,%f2,%f0
45 	 * fmovsle	%fcc0,%f3,%f1
46 	 * fsubs	%f0,%f1,%f0
47 	 */
48 	if (islessequal(x, y)) {
49 		x = 0.0f;
50 		y = -x;
51 	}
52 	return (x - y);
53 }
54