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 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
23 */
24 /*
25 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
26 * Use is subject to license terms.
27 */
28
29 #pragma weak __remainder = remainder
30
31 /*
32 * remainder(x,p)
33 * Code originated from 4.3bsd.
34 * Modified by K.C. Ng for SUN 4.0 libm.
35 * Return :
36 * returns x REM p = x - [x/p]*p as if in infinite precise arithmetic,
37 * where [x/p] is the (inifinite bit) integer nearest x/p (in half way
38 * case choose the even one).
39 * Method :
40 * Based on fmod() return x-[x/p]chopped*p exactly.
41 */
42
43 #include "libm.h"
44
45 static const double zero = 0.0, half = 0.5;
46
47 double
remainder(double x,double p)48 remainder(double x, double p) {
49 double halfp;
50 int ix, hx, hp;
51
52 ix = ((int *)&x)[HIWORD];
53 hx = ix & ~0x80000000;
54 hp = ((int *)&p)[HIWORD] & ~0x80000000;
55
56 if (hp > 0x7ff00000 || (hp == 0x7ff00000 && ((int *)&p)[LOWORD] != 0))
57 return (x * p);
58 if (hx > 0x7ff00000 || (hx == 0x7ff00000 && ((int *)&x)[LOWORD] != 0))
59 return (x * p);
60
61 if ((hp | ((int *)&p)[LOWORD]) == 0 || hx == 0x7ff00000)
62 return (_SVID_libm_err(x, p, 28));
63
64 p = fabs(p);
65 if (hp < 0x7fe00000)
66 x = fmod(x, p + p);
67 x = fabs(x);
68 if (hp < 0x00200000) {
69 if (x + x > p) {
70 if (x == p) /* avoid x-x=-0 in RM mode */
71 return ((ix < 0)? -zero : zero);
72 x -= p;
73 if (x + x >= p)
74 x -= p;
75 }
76 } else {
77 halfp = half * p;
78 if (x > halfp) {
79 if (x == p) /* avoid x-x=-0 in RM mode */
80 return ((ix < 0)? -zero : zero);
81 x -= p;
82 if (x >= halfp)
83 x -= p;
84 }
85 }
86 return ((ix < 0)? -x : x);
87 }
88