/[jscoverage]/trunk/js/src/fdlibm/e_remainder.c
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Annotation of /trunk/js/src/fdlibm/e_remainder.c

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Wed Aug 1 13:51:53 2007 UTC (14 years, 11 months ago) by siliconforks
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Initial import.

1 siliconforks 2 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2     *
3     * ***** BEGIN LICENSE BLOCK *****
4     * Version: MPL 1.1/GPL 2.0/LGPL 2.1
5     *
6     * The contents of this file are subject to the Mozilla Public License Version
7     * 1.1 (the "License"); you may not use this file except in compliance with
8     * the License. You may obtain a copy of the License at
9     * http://www.mozilla.org/MPL/
10     *
11     * Software distributed under the License is distributed on an "AS IS" basis,
12     * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13     * for the specific language governing rights and limitations under the
14     * License.
15     *
16     * The Original Code is Mozilla Communicator client code, released
17     * March 31, 1998.
18     *
19     * The Initial Developer of the Original Code is
20     * Sun Microsystems, Inc.
21     * Portions created by the Initial Developer are Copyright (C) 1998
22     * the Initial Developer. All Rights Reserved.
23     *
24     * Contributor(s):
25     *
26     * Alternatively, the contents of this file may be used under the terms of
27     * either of the GNU General Public License Version 2 or later (the "GPL"),
28     * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29     * in which case the provisions of the GPL or the LGPL are applicable instead
30     * of those above. If you wish to allow use of your version of this file only
31     * under the terms of either the GPL or the LGPL, and not to allow others to
32     * use your version of this file under the terms of the MPL, indicate your
33     * decision by deleting the provisions above and replace them with the notice
34     * and other provisions required by the GPL or the LGPL. If you do not delete
35     * the provisions above, a recipient may use your version of this file under
36     * the terms of any one of the MPL, the GPL or the LGPL.
37     *
38     * ***** END LICENSE BLOCK ***** */
39    
40     /* @(#)e_remainder.c 1.3 95/01/18 */
41     /*
42     * ====================================================
43     * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
44     *
45     * Developed at SunSoft, a Sun Microsystems, Inc. business.
46     * Permission to use, copy, modify, and distribute this
47     * software is freely granted, provided that this notice
48     * is preserved.
49     * ====================================================
50     */
51    
52     /* __ieee754_remainder(x,p)
53     * Return :
54     * returns x REM p = x - [x/p]*p as if in infinite
55     * precise arithmetic, where [x/p] is the (infinite bit)
56     * integer nearest x/p (in half way case choose the even one).
57     * Method :
58     * Based on fmod() return x-[x/p]chopped*p exactlp.
59     */
60    
61     #include "fdlibm.h"
62    
63     #ifdef __STDC__
64     static const double zero = 0.0;
65     #else
66     static double zero = 0.0;
67     #endif
68    
69    
70     #ifdef __STDC__
71     double __ieee754_remainder(double x, double p)
72     #else
73     double __ieee754_remainder(x,p)
74     double x,p;
75     #endif
76     {
77     fd_twoints u;
78     int hx,hp;
79     unsigned sx,lx,lp;
80     double p_half;
81    
82     u.d = x;
83     hx = __HI(u); /* high word of x */
84     lx = __LO(u); /* low word of x */
85     u.d = p;
86     hp = __HI(u); /* high word of p */
87     lp = __LO(u); /* low word of p */
88     sx = hx&0x80000000;
89     hp &= 0x7fffffff;
90     hx &= 0x7fffffff;
91    
92     /* purge off exception values */
93     if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */
94     if((hx>=0x7ff00000)|| /* x not finite */
95     ((hp>=0x7ff00000)&& /* p is NaN */
96     (((hp-0x7ff00000)|lp)!=0)))
97     return (x*p)/(x*p);
98    
99    
100     if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */
101     if (((hx-hp)|(lx-lp))==0) return zero*x;
102     x = fd_fabs(x);
103     p = fd_fabs(p);
104     if (hp<0x00200000) {
105     if(x+x>p) {
106     x-=p;
107     if(x+x>=p) x -= p;
108     }
109     } else {
110     p_half = 0.5*p;
111     if(x>p_half) {
112     x-=p;
113     if(x>=p_half) x -= p;
114     }
115     }
116     u.d = x;
117     __HI(u) ^= sx;
118     x = u.d;
119     return x;
120     }

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