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 /* @(#)s_modf.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 /* 53 * modf(double x, double *iptr) 54 * return fraction part of x, and return x's integral part in *iptr. 55 * Method: 56 * Bit twiddling. 57 * 58 * Exception: 59 * No exception. 60 */ 61 62 #include "fdlibm.h" 63 64 #ifdef __STDC__ 65 static const double one = 1.0; 66 #else 67 static double one = 1.0; 68 #endif 69 70 #ifdef __STDC__ fd_modf(double x,double * iptr)71 double fd_modf(double x, double *iptr) 72 #else 73 double fd_modf(x, iptr) 74 double x,*iptr; 75 #endif 76 { 77 int i0,i1,j0; 78 unsigned i; 79 fd_twoints u; 80 u.d = x; 81 i0 = __HI(u); /* high x */ 82 i1 = __LO(u); /* low x */ 83 j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ 84 if(j0<20) { /* integer part in high x */ 85 if(j0<0) { /* |x|<1 */ 86 u.d = *iptr; 87 __HI(u) = i0&0x80000000; 88 __LO(u) = 0; /* *iptr = +-0 */ 89 *iptr = u.d; 90 return x; 91 } else { 92 i = (0x000fffff)>>j0; 93 if(((i0&i)|i1)==0) { /* x is integral */ 94 *iptr = x; 95 u.d = x; 96 __HI(u) &= 0x80000000; 97 __LO(u) = 0; /* return +-0 */ 98 x = u.d; 99 return x; 100 } else { 101 u.d = *iptr; 102 __HI(u) = i0&(~i); 103 __LO(u) = 0; 104 *iptr = u.d; 105 return x - *iptr; 106 } 107 } 108 } else if (j0>51) { /* no fraction part */ 109 *iptr = x*one; 110 u.d = x; 111 __HI(u) &= 0x80000000; 112 __LO(u) = 0; /* return +-0 */ 113 x = u.d; 114 return x; 115 } else { /* fraction part in low x */ 116 i = ((unsigned)(0xffffffff))>>(j0-20); 117 if((i1&i)==0) { /* x is integral */ 118 *iptr = x; 119 u.d = x; 120 __HI(u) &= 0x80000000; 121 __LO(u) = 0; /* return +-0 */ 122 x = u.d; 123 return x; 124 } else { 125 u.d = *iptr; 126 __HI(u) = i0; 127 __LO(u) = i1&(~i); 128 *iptr = u.d; 129 return x - *iptr; 130 } 131 } 132 } 133