s_cosl.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: stable/11/lib/msun/src/s_cosl.c 330897 2018-03-14 03:19:51Z eadler $");
31
32/*
33 * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows
34 * an accuracy of <= 0.7412 ULP.
35 */
36
37#include <float.h>
38#ifdef __i386__
39#include <ieeefp.h>
40#endif
41
42#include "math.h"
43#include "math_private.h"
44#if LDBL_MANT_DIG == 64
45#include "../ld80/e_rem_pio2l.h"
46#elif LDBL_MANT_DIG == 113
47#include "../ld128/e_rem_pio2l.h"
48#else
49#error "Unsupported long double format"
50#endif
51
52long double
53cosl(long double x)
54{
55	union IEEEl2bits z;
56	int e0;
57	long double y[2];
58	long double hi, lo;
59
60	z.e = x;
61	z.bits.sign = 0;
62
63	/* If x = +-0 or x is a subnormal number, then cos(x) = 1 */
64	if (z.bits.exp == 0)
65		return (1.0);
66
67	/* If x = NaN or Inf, then cos(x) = NaN. */
68	if (z.bits.exp == 32767)
69		return ((x - x) / (x - x));
70
71	ENTERI();
72
73	/* Optimize the case where x is already within range. */
74	if (z.e < M_PI_4)
75		RETURNI(__kernel_cosl(z.e, 0));
76
77	e0 = __ieee754_rem_pio2l(x, y);
78	hi = y[0];
79	lo = y[1];
80
81	switch (e0 & 3) {
82	case 0:
83	    hi = __kernel_cosl(hi, lo);
84	    break;
85	case 1:
86	    hi = - __kernel_sinl(hi, lo, 1);
87	    break;
88	case 2:
89	    hi = - __kernel_cosl(hi, lo);
90	    break;
91	case 3:
92	    hi = __kernel_sinl(hi, lo, 1);
93	    break;
94	}
95
96	RETURNI(hi);
97}
98