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 __tanl = tanl
31
32 /* INDENT OFF */
33 /* cosl(x)
34 * Table look-up algorithm by K.C. Ng, November, 1989.
35 *
36 * kernel function:
37 * __k_tanl ... tangent 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 long double
tanl(long double x)70 tanl(long double x) {
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 return x - x;
80
81 /* High word of x. */
82 #if defined(__i386) || defined(__amd64)
83 XTOI(px, ix);
84 #else
85 ix = *(int *) &x;
86 #endif
87
88 /* |x| ~< pi/4 */
89 ix &= 0x7fffffff;
90 if (ix <= 0x3ffe9220)
91 return __k_tanl(x, z, 0);
92
93 /* argument reduction needed */
94 else {
95 n = __rem_pio2l(x, y);
96 return __k_tanl(y[0], y[1], n & 1);
97 }
98 }
99