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

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Revision 2 - (show annotations)
Wed Aug 1 13:51:53 2007 UTC (14 years, 9 months ago) by siliconforks
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Initial import.

1 /* -*- 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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