1 /* $NetBSD: s_cosl.c,v 1.3 2024/05/08 01:42:23 riastradh Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-2-Clause
5 *
6 * Copyright (c) 2007 Steven G. Kargl
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice unmodified, this list of conditions, and the following
14 * disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: s_cosl.c,v 1.3 2024/05/08 01:42:23 riastradh Exp $");
33
34 /*
35 * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows
36 * an accuracy of <= 0.7412 ULP.
37 */
38
39 #include "namespace.h"
40 #include <float.h>
41
42 #ifdef __weak_alias
43 __weak_alias(cosl, _cosl)
44 #endif
45
46
47 #ifdef __FreeBSD__
48 #include "fpmath.h"
49 #endif
50
51 #include "math.h"
52 #include "math_private.h"
53
54 #ifdef __HAVE_LONG_DOUBLE
55
56 #if LDBL_MANT_DIG == 64
57 #include "../ld80/e_rem_pio2l.h"
58 #include "../ld80/k_cosl.c"
59 static const union ieee_ext_u
60 pio4u = LD80C(0xc90fdaa22168c235, -00001, 7.85398163397448309628e-01L);
61 #define pio4 (pio4u.extu_ld)
62 #elif LDBL_MANT_DIG == 113
63 #include "../ld128/e_rem_pio2l.h"
64 #include "../ld128/k_cosl.c"
65 static long double pio4 = 7.85398163397448309615660845819875721e-1L;
66 #else
67 #error "Unsupported long double format"
68 #endif
69
70 long double
cosl(long double x)71 cosl(long double x)
72 {
73 union ieee_ext_u z;
74 int e0;
75 long double y[2];
76 long double hi, lo;
77
78 z.extu_ld = x;
79 z.extu_sign = 0;
80
81 /* If x = +-0 or x is a subnormal number, then cos(x) = 1 */
82 if (z.extu_exp == 0)
83 return (1.0);
84
85 /* If x = NaN or Inf, then cos(x) = NaN. */
86 if (z.extu_exp == 32767)
87 return ((x - x) / (x - x));
88
89 ENTERI();
90
91 /* Optimize the case where x is already within range. */
92 if (z.extu_ld < pio4)
93 RETURNI(__kernel_cosl(z.extu_ld, 0));
94
95 e0 = __ieee754_rem_pio2l(x, y);
96 hi = y[0];
97 lo = y[1];
98
99 switch (e0 & 3) {
100 case 0:
101 hi = __kernel_cosl(hi, lo);
102 break;
103 case 1:
104 hi = - __kernel_sinl(hi, lo, 1);
105 break;
106 case 2:
107 hi = - __kernel_cosl(hi, lo);
108 break;
109 case 3:
110 hi = __kernel_sinl(hi, lo, 1);
111 break;
112 }
113
114 RETURNI(hi);
115 }
116 #else
117
118 long double
119 cosl(long double x)
120 {
121 return cos(x);
122 }
123
124 #endif
125