1 /* 2 * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* __ieee754_remainder(x,p) 27 * Return : 28 * returns x REM p = x - [x/p]*p as if in infinite 29 * precise arithmetic, where [x/p] is the (infinite bit) 30 * integer nearest x/p (in half way case choose the even one). 31 * Method : 32 * Based on fmod() return x-[x/p]chopped*p exactlp. 33 */ 34 35 #include "fdlibm.h" 36 37 #ifdef __STDC__ 38 static const double zero = 0.0; 39 #else 40 static double zero = 0.0; 41 #endif 42 43 44 #ifdef __STDC__ __ieee754_remainder(double x,double p)45 double __ieee754_remainder(double x, double p) 46 #else 47 double __ieee754_remainder(x,p) 48 double x,p; 49 #endif 50 { 51 int hx,hp; 52 unsigned sx,lx,lp; 53 double p_half; 54 55 hx = __HI(x); /* high word of x */ 56 lx = __LO(x); /* low word of x */ 57 hp = __HI(p); /* high word of p */ 58 lp = __LO(p); /* low word of p */ 59 sx = hx&0x80000000; 60 hp &= 0x7fffffff; 61 hx &= 0x7fffffff; 62 63 /* purge off exception values */ 64 if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */ 65 if((hx>=0x7ff00000)|| /* x not finite */ 66 ((hp>=0x7ff00000)&& /* p is NaN */ 67 (((hp-0x7ff00000)|lp)!=0))) 68 return (x*p)/(x*p); 69 70 71 if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */ 72 if (((hx-hp)|(lx-lp))==0) return zero*x; 73 x = fabs(x); 74 p = fabs(p); 75 if (hp<0x00200000) { 76 if(x+x>p) { 77 x-=p; 78 if(x+x>=p) x -= p; 79 } 80 } else { 81 p_half = 0.5*p; 82 if(x>p_half) { 83 x-=p; 84 if(x>=p_half) x -= p; 85 } 86 } 87 __HI(x) ^= sx; 88 return x; 89 } 90