1 /* origin: FreeBSD /usr/src/lib/msun/src/s_sin.c */
2 /*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13 #define _GNU_SOURCE
14 #include "libm.h"
15
sincos(double x,double * sin,double * cos)16 void sincos(double x, double *sin, double *cos)
17 {
18 double y[2], s, c;
19 uint32_t ix;
20 unsigned n;
21
22 GET_HIGH_WORD(ix, x);
23 ix &= 0x7fffffff;
24
25 /* |x| ~< pi/4 */
26 if (ix <= 0x3fe921fb) {
27 /* if |x| < 2**-27 * sqrt(2) */
28 if (ix < 0x3e46a09e) {
29 /* raise inexact if x!=0 and underflow if subnormal */
30 FORCE_EVAL(ix < 0x00100000 ? x/0x1p120f : x+0x1p120f);
31 *sin = x;
32 *cos = 1.0;
33 return;
34 }
35 *sin = __sin(x, 0.0, 0);
36 *cos = __cos(x, 0.0);
37 return;
38 }
39
40 /* sincos(Inf or NaN) is NaN */
41 if (ix >= 0x7ff00000) {
42 *sin = *cos = x - x;
43 return;
44 }
45
46 /* argument reduction needed */
47 n = __rem_pio2(x, y);
48 s = __sin(y[0], y[1], 1);
49 c = __cos(y[0], y[1]);
50 switch (n&3) {
51 case 0:
52 *sin = s;
53 *cos = c;
54 break;
55 case 1:
56 *sin = c;
57 *cos = -s;
58 break;
59 case 2:
60 *sin = -s;
61 *cos = -c;
62 break;
63 case 3:
64 default:
65 *sin = -c;
66 *cos = s;
67 break;
68 }
69 }
70