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 /*
31  * __rem_pio2l(x,y)
32  *
33  * return the remainder of x rem pi/2 in y[0]+y[1]
34  * by calling __rem_pio2m
35  */
36 
37 #include "libm.h"
38 #include "longdouble.h"
39 
40 extern const int _TBL_ipio2l_inf[];
41 
42 static const long double
43     two24l = 16777216.0L,
44     pio4   = 0.7853981633974483096156608458198757210495L;
45 
46 int
47 __rem_pio2l(long double x, long double *y)
48 {
49 	long double	z, w;
50 	double		t[3], v[5];
51 	int		e0, i, nx, n, sign;
52 
53 	sign = signbitl(x);
54 	z = fabsl(x);
55 	if (z <= pio4) {
56 		y[0] = x;
57 		y[1] = 0;
58 		return (0);
59 	}
60 	e0 = ilogbl(z) - 23;
61 	z = scalbnl(z, -e0);
62 	for (i = 0; i < 3; i++) {
63 		t[i] = (double)((int)(z));
64 		z = (z - (long double)t[i]) * two24l;
65 	}
66 	nx = 3;
67 	while (t[nx-1] == 0.0)
68 		nx--;	/* omit trailing zeros */
69 	n = __rem_pio2m(t, v, e0, nx, 2, _TBL_ipio2l_inf);
70 	z = (long double)v[1];
71 	w = (long double)v[0];
72 	y[0] = z + w;
73 	y[1] = z - (y[0] - w);
74 	if (sign != 0) {
75 		y[0] = -y[0];
76 		y[1] = -y[1];
77 		return (-n);
78 	}
79 	return (n);
80 }
81