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 /* 27 * for non-zero x 28 * x = frexp(arg,&exp); 29 * return a double fp quantity x such that 0.5 <= |x| <1.0 30 * and the corresponding binary exponent "exp". That is 31 * arg = x*2^exp. 32 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg 33 * with *exp=0. 34 */ 35 36 #include "fdlibm.h" 37 38 #ifdef __STDC__ 39 static const double 40 #else 41 static double 42 #endif 43 two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ 44 45 #ifdef __STDC__ frexp(double x,int * eptr)46 double frexp(double x, int *eptr) 47 #else 48 double frexp(x, eptr) 49 double x; int *eptr; 50 #endif 51 { 52 int hx, ix, lx; 53 hx = __HI(x); 54 ix = 0x7fffffff&hx; 55 lx = __LO(x); 56 *eptr = 0; 57 if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */ 58 if (ix<0x00100000) { /* subnormal */ 59 x *= two54; 60 hx = __HI(x); 61 ix = hx&0x7fffffff; 62 *eptr = -54; 63 } 64 *eptr += (ix>>20)-1022; 65 hx = (hx&0x800fffff)|0x3fe00000; 66 __HI(x) = hx; 67 return x; 68 } 69