1 /* @(#)s_nextafter.c 5.1 93/09/24 */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
12 * $NetBSD: s_nextafter.c,v 1.11 2002/05/26 22:01:57 wiz Exp $
13 * $DragonFly: src/lib/libm/src/s_nextafter.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
18 * return the next machine floating-point number of x in the
24 #include "math_private.h"
27 nextafter(double x, double y)
32 EXTRACT_WORDS(hx,lx,x);
33 EXTRACT_WORDS(hy,ly,y);
34 ix = hx&0x7fffffff; /* |x| */
35 iy = hy&0x7fffffff; /* |y| */
37 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
38 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
40 if(x==y) return x; /* x=y, return x */
41 if((ix|lx)==0) { /* x == 0 */
42 INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */
44 if(y==x) return y; else return x; /* raise underflow flag */
46 if(hx>=0) { /* x > 0 */
47 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
50 } else { /* x < y, x += ulp */
55 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
58 } else { /* x > y, x += ulp */
64 if(hy>=0x7ff00000) return x+x; /* overflow */
65 if(hy<0x00100000) { /* underflow */
67 if(y!=x) { /* raise underflow flag */
68 INSERT_WORDS(y,hx,lx);
72 INSERT_WORDS(x,hx,lx);