xref: /titanic_41/usr/src/lib/libm/common/LD/sincosl.c (revision 7206bf49b1fe641544165ee97f63856da95e0868)
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 __sincosl = sincosl
31 
32 /* INDENT OFF */
33 /* cosl(x)
34  * Table look-up algorithm by K.C. Ng, November, 1989.
35  *
36  * kernel function:
37  *	__k_sincosl	... sin and cos function on [-pi/4,pi/4]
38  *	__rem_pio2l	... argument reduction routine
39  *
40  * Method.
41  *      Let S and C denote the sin and cos respectively on [-PI/4, +PI/4].
42  *      1. Assume the argument x is reduced to y1+y2 = x-k*pi/2 in
43  *	   [-pi/2 , +pi/2], and let n = k mod 4.
44  *	2. Let S=S(y1+y2), C=C(y1+y2). Depending on n, we have
45  *
46  *          n        sin(x)      cos(x)        tan(x)
47  *     ----------------------------------------------------------
48  *	    0	       S	   C		 S/C
49  *	    1	       C	  -S		-C/S
50  *	    2	      -S	  -C		 S/C
51  *	    3	      -C	   S		-C/S
52  *     ----------------------------------------------------------
53  *
54  * Special cases:
55  *      Let trig be any of sin, cos, or tan.
56  *      trig(+-INF)  is NaN, with signals;
57  *      trig(NaN)    is that NaN;
58  *
59  * Accuracy:
60  *	computer TRIG(x) returns trig(x) nearly rounded.
61  */
62 /* INDENT ON */
63 
64 #include "libm.h"
65 #include "longdouble.h"
66 
67 #include <sys/isa_defs.h>
68 
69 void
70 sincosl(long double x, long double *s, long double *c) {
71 	long double y[2], z = 0.0L;
72 	int n, ix;
73 #if defined(__i386) || defined(__amd64)
74 	int *px = (int *) &x;
75 #endif
76 
77 	/* trig(Inf or NaN) is NaN */
78 	if (!finitel(x)) {
79 		*s = *c = x - x;
80 		return;
81 	}
82 
83 	/* High word of x. */
84 #if defined(__i386) || defined(__amd64)
85 	XTOI(px, ix);
86 #else
87 	ix = *(int *) &x;
88 #endif
89 
90 	/* |x| ~< pi/4 */
91 	ix &= 0x7fffffff;
92 	if (ix <= 0x3ffe9220)
93 		*s = __k_sincosl(x, z, c);
94 
95 	/* argument reduction needed */
96 	else {
97 		n = __rem_pio2l(x, y);
98 		switch (n & 3) {
99 		case 0:
100 			*s = __k_sincosl(y[0], y[1], c);
101 			break;
102 		case 1:
103 			*c = -__k_sincosl(y[0], y[1], s);
104 			break;
105 		case 2:
106 			*s = -__k_sincosl(y[0], y[1], c);
107 			*c = -*c;
108 			break;
109 		case 3:
110 			*c = __k_sincosl(y[0], y[1], s);
111 			*s = -*s;
112 		}
113 	}
114 }
115