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_nextafter.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 /* IEEE functions 53 * nextafter(x,y) 54 * return the next machine floating-point number of x in the 55 * direction toward y. 56 * Special cases: 57 */ 58 59 #include "fdlibm.h" 60 61 #ifdef __STDC__ fd_nextafter(double x,double y)62 double fd_nextafter(double x, double y) 63 #else 64 double fd_nextafter(x,y) 65 double x,y; 66 #endif 67 { 68 int hx,hy,ix,iy; 69 unsigned lx,ly; 70 fd_twoints ux, uy; 71 72 ux.d = x; uy.d = y; 73 hx = __HI(ux); /* high word of x */ 74 lx = __LO(ux); /* low word of x */ 75 hy = __HI(uy); /* high word of y */ 76 ly = __LO(uy); /* low word of y */ 77 ix = hx&0x7fffffff; /* |x| */ 78 iy = hy&0x7fffffff; /* |y| */ 79 80 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ 81 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ 82 return x+y; 83 if(x==y) return x; /* x=y, return x */ 84 if((ix|lx)==0) { /* x == 0 */ 85 ux.d = x; 86 __HI(ux) = hy&0x80000000; /* return +-minsubnormal */ 87 __LO(ux) = 1; 88 x = ux.d; 89 y = x*x; 90 if(y==x) return y; else return x; /* raise underflow flag */ 91 } 92 if(hx>=0) { /* x > 0 */ 93 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ 94 if(lx==0) hx -= 1; 95 lx -= 1; 96 } else { /* x < y, x += ulp */ 97 lx += 1; 98 if(lx==0) hx += 1; 99 } 100 } else { /* x < 0 */ 101 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ 102 if(lx==0) hx -= 1; 103 lx -= 1; 104 } else { /* x > y, x += ulp */ 105 lx += 1; 106 if(lx==0) hx += 1; 107 } 108 } 109 hy = hx&0x7ff00000; 110 if(hy>=0x7ff00000) return x+x; /* overflow */ 111 if(hy<0x00100000) { /* underflow */ 112 y = x*x; 113 if(y!=x) { /* raise underflow flag */ 114 uy.d = y; 115 __HI(uy) = hx; __LO(uy) = lx; 116 y = uy.d; 117 return y; 118 } 119 } 120 ux.d = x; 121 __HI(ux) = hx; __LO(ux) = lx; 122 x = ux.d; 123 return x; 124 } 125