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 #pragma weak __remainderl = remainderl
31
32 #include "libm.h"
33 #include "longdouble.h"
34
35 /*
36 * remainderl(x,p)
37 * returns x REM p = x - [x/p]*p as if in infinite
38 * precise arithmetic, where [x/p] is the (inifinite bit)
39 * integer nearest x/p (in half way case choose the even one).
40 * Method :
41 * Based on fmodl() return x-[x/p]chopped*p exactly.
42 */
43
44 #define HFMAX 5.948657476786158825428796633140035080982e+4931L
45 #define DBMIN 6.724206286224187012525355634643505205196e-4932L
46
47 static const long double
48 zero = 0.0L,
49 half = 0.5L,
50 hfmax = HFMAX, /* half of the maximum number */
51 dbmin = DBMIN; /* double of the minimum (normal) number */
52
53 long double
remainderl(long double x,long double p)54 remainderl(long double x, long double p) {
55 long double hp;
56 int sx;
57
58 if (isnanl(p))
59 return (x + p);
60 if (!finitel(x))
61 return (x - x);
62 p = fabsl(p);
63 if (p <= hfmax)
64 x = fmodl(x, p + p);
65 sx = signbitl(x);
66 x = fabsl(x);
67 if (p < dbmin) {
68 if (x + x > p) {
69 if (x == p)
70 x = zero;
71 else
72 x -= p; /* avoid x-x=-0 in RM mode */
73 if (x + x >= p)
74 x -= p;
75 }
76 } else {
77 hp = half * p;
78 if (x > hp) {
79 if (x == p)
80 x = zero;
81 else
82 x -= p; /* avoid x-x=-0 in RM mode */
83 if (x >= hp)
84 x -= p;
85 }
86 }
87 return (sx == 0 ? x : -x);
88 }
89