xref: /titanic_52/usr/src/lib/libm/common/Q/nextafterl.c (revision 786d1eec1cd1cac7e26243d118cd209e84bc6bb9)
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 nextafterl = __nextafterl
32 #endif
33 
34 #include "libm.h"
35 #include <float.h>		/* LDBL_MAX, LDBL_MIN */
36 
37 #if defined(__sparc)
38 #define	n0	0
39 #define	n1	1
40 #define	n2	2
41 #define	n3	3
42 #define	X86PDNRM1(x)
43 #define	INC(px)	{ \
44 			if (++px[n3] == 0) \
45 				if (++px[n2] == 0) \
46 					if (++px[n1] == 0) \
47 						++px[n0]; \
48 		}
49 #define	DEC(px)	{ \
50 			if (--px[n3] == 0xffffffff) \
51 				if (--px[n2] == 0xffffffff) \
52 					if (--px[n1] == 0xffffffff) \
53 						--px[n0]; \
54 		}
55 #elif defined(__x86)
56 #define	n0	2
57 #define	n1	1
58 #define	n2	0
59 #define	n3	0
60 /*
61  * if pseudo-denormal, replace by the equivalent normal
62  */
63 #define	X86PDNRM1(x)	if (XBIASED_EXP(x) == 0 && (((int *) &x)[1] & \
64 				0x80000000) != 0) \
65 				((int *) &x)[2] |= 1
66 #define	INC(px)	{ \
67 			if (++px[n2] == 0) \
68 				if ((++px[n1] & ~0x80000000) == 0) \
69 					px[n1] = 0x80000000, ++px[n0]; \
70 		}
71 #define	DEC(px)	{ \
72 			if (--px[n2] == 0xffffffff) \
73 				if (--px[n1] == 0x7fffffff) \
74 					if ((--px[n0] & 0x7fff) != 0) \
75 						px[n1] |= 0x80000000; \
76 		}
77 #endif
78 
79 long double
80 nextafterl(long double x, long double y) {
81 	int *px = (int *) &x;
82 	int *py = (int *) &y;
83 
84 	if (x == y)
85 		return (y);		/* C99 requirement */
86 	if (x != x || y != y)
87 		return (x * y);
88 
89 	if (ISZEROL(x)) {	/* x == 0.0 */
90 		px[n0] = py[n0] & XSGNMSK;
91 		px[n1] = px[n2] = 0;
92 		px[n3] = 1;
93 	} else {
94 		X86PDNRM1(x);
95 		if ((px[n0] & XSGNMSK) == 0) {	/* x > 0.0 */
96 			if (x > y)	/* x > y */
97 				DEC(px)
98 			else
99 				INC(px)
100 		} else {
101 			if (x < y)	/* x < y */
102 				DEC(px)
103 			else
104 				INC(px)
105 		}
106 	}
107 #ifndef lint
108 	{
109 		volatile long double dummy;
110 		int k = XBIASED_EXP(x);
111 
112 		if (k == 0)
113 			dummy = LDBL_MIN * copysignl(LDBL_MIN, x);
114 		else if (k == 0x7fff)
115 			dummy = LDBL_MAX * copysignl(LDBL_MAX, x);
116 	}
117 #endif
118 	return (x);
119 }
120