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_ilogb.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 /* ilogb(double x) 53 * return the binary exponent of non-zero x 54 * ilogb(0) = 0x80000001 55 * ilogb(inf/NaN) = 0x7fffffff (no signal is raised) 56 */ 57 58 #include "fdlibm.h" 59 60 #ifdef __STDC__ fd_ilogb(double x)61 int fd_ilogb(double x) 62 #else 63 int fd_ilogb(x) 64 double x; 65 #endif 66 { 67 int hx,lx,ix; 68 fd_twoints u; 69 u.d = x; 70 hx = (__HI(u))&0x7fffffff; /* high word of x */ 71 if(hx<0x00100000) { 72 lx = __LO(u); 73 if((hx|lx)==0) 74 return 0x80000001; /* ilogb(0) = 0x80000001 */ 75 else /* subnormal x */ 76 if(hx==0) { 77 for (ix = -1043; lx>0; lx<<=1) ix -=1; 78 } else { 79 for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; 80 } 81 return ix; 82 } 83 else if (hx<0x7ff00000) return (hx>>20)-1023; 84 else return 0x7fffffff; 85 } 86