1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2007 Steven G. Kargl
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice unmodified, this list of conditions, and the following
12 *    disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*
30 * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows
31 * an accuracy of <= 0.7412 ULP.
32 */
33
34#include <float.h>
35#ifdef __i386__
36#include <ieeefp.h>
37#endif
38
39#include "fpmath.h"
40#include "math.h"
41#include "math_private.h"
42#if LDBL_MANT_DIG == 64
43#include "../ld80/e_rem_pio2l.h"
44static const union IEEEl2bits
45pio4u = LD80C(0xc90fdaa22168c235, -00001,  7.85398163397448309628e-01L);
46#define	pio4	(pio4u.e)
47#elif LDBL_MANT_DIG == 113
48#include "../ld128/e_rem_pio2l.h"
49long double pio4 =  7.85398163397448309615660845819875721e-1L;
50#else
51#error "Unsupported long double format"
52#endif
53
54long double
55cosl(long double x)
56{
57	union IEEEl2bits z;
58	int e0;
59	long double y[2];
60	long double hi, lo;
61
62	z.e = x;
63	z.bits.sign = 0;
64
65	/* If x = +-0 or x is a subnormal number, then cos(x) = 1 */
66	if (z.bits.exp == 0)
67		return (1.0);
68
69	/* If x = NaN or Inf, then cos(x) = NaN. */
70	if (z.bits.exp == 32767)
71		return ((x - x) / (x - x));
72
73	ENTERI();
74
75	/* Optimize the case where x is already within range. */
76	if (z.e < pio4)
77		RETURNI(__kernel_cosl(z.e, 0));
78
79	e0 = __ieee754_rem_pio2l(x, y);
80	hi = y[0];
81	lo = y[1];
82
83	switch (e0 & 3) {
84	case 0:
85	    hi = __kernel_cosl(hi, lo);
86	    break;
87	case 1:
88	    hi = - __kernel_sinl(hi, lo, 1);
89	    break;
90	case 2:
91	    hi = - __kernel_cosl(hi, lo);
92	    break;
93	case 3:
94	    hi = __kernel_sinl(hi, lo, 1);
95	    break;
96	}
97
98	RETURNI(hi);
99}
100