xref: /titanic_50/usr/src/lib/libm/common/R/nextafterf.c (revision 6aa4fc89ec1cf2cdf7d7c3b9ec059802ac9abe65)
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 nextafterf = __nextafterf
32 #endif
33 
34 #include "libm.h"
35 
36 float
37 nextafterf(float x, float y) {
38 	float w;
39 	int *pw = (int *) &w;
40 	int *px = (int *) &x;
41 	int *py = (int *) &y;
42 	int ix, iy, iz;
43 
44 	ix = px[0];
45 	iy = py[0];
46 	if ((ix & ~0x80000000) > 0x7f800000)
47 		return (x * y);		/* + -> * for Cheetah */
48 	if ((iy & ~0x80000000) > 0x7f800000)
49 		return (y * x);		/* + -> * for Cheetah */
50 	if (ix == iy || (ix | iy) == 0x80000000)
51 		return (y);		/* C99 requirement */
52 	if ((ix & ~0x80000000) == 0)
53 		iz = 1 | (iy & 0x80000000);
54 	else if (ix > 0) {
55 		if (ix > iy)
56 			iz = ix - 1;
57 		else
58 			iz = ix + 1;
59 	} else {
60 		if (iy < 0 && ix < iy)
61 			iz = ix + 1;
62 		else
63 			iz = ix - 1;
64 	}
65 	pw[0] = iz;
66 	ix = iz & 0x7f800000;
67 	if (ix == 0x7f800000) {
68 		/* raise overflow */
69 		volatile float t;
70 
71 		*(int *) &t = 0x7f7fffff;
72 		t *= t;
73 	} else if (ix == 0) {
74 		/* raise underflow */
75 		volatile float t;
76 
77 		*(int *) &t = 0x00800000;
78 		t *= t;
79 	}
80 	return (w);
81 }
82