xref: /illumos-gate/usr/src/lib/libm/common/R/nextafterf.c (revision 132157d7fb25c120ae1deca2a65fa7c78e8fcfd0)
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 __nextafterf = nextafterf
31 
32 #include "libm.h"
33 
34 float
35 nextafterf(float x, float y) {
36 	float w;
37 	int *pw = (int *) &w;
38 	int *px = (int *) &x;
39 	int *py = (int *) &y;
40 	int ix, iy, iz;
41 
42 	ix = px[0];
43 	iy = py[0];
44 	if ((ix & ~0x80000000) > 0x7f800000)
45 		return (x * y);		/* + -> * for Cheetah */
46 	if ((iy & ~0x80000000) > 0x7f800000)
47 		return (y * x);		/* + -> * for Cheetah */
48 	if (ix == iy || (ix | iy) == 0x80000000)
49 		return (y);		/* C99 requirement */
50 	if ((ix & ~0x80000000) == 0)
51 		iz = 1 | (iy & 0x80000000);
52 	else if (ix > 0) {
53 		if (ix > iy)
54 			iz = ix - 1;
55 		else
56 			iz = ix + 1;
57 	} else {
58 		if (iy < 0 && ix < iy)
59 			iz = ix + 1;
60 		else
61 			iz = ix - 1;
62 	}
63 	pw[0] = iz;
64 	ix = iz & 0x7f800000;
65 	if (ix == 0x7f800000) {
66 		/* raise overflow */
67 		volatile float t;
68 
69 		*(int *) &t = 0x7f7fffff;
70 		t *= t;
71 	} else if (ix == 0) {
72 		/* raise underflow */
73 		volatile float t;
74 
75 		*(int *) &t = 0x00800000;
76 		t *= t;
77 	}
78 	return (w);
79 }
80