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 * $FreeBSD: src/lib/msun/src/s_nextafter.c,v 1.5 1999/08/28 00:06:53 peter Exp $
13 * $DragonFly: src/lib/msun/src/Attic/s_nextafter.c,v 1.2 2003/06/17 04:26:53 dillon Exp $
18 * return the next machine floating-point number of x in the
24 #include "math_private.h"
27 double nextafter(double x, double y)
36 EXTRACT_WORDS(hx,lx,x);
37 EXTRACT_WORDS(hy,ly,y);
38 ix = hx&0x7fffffff; /* |x| */
39 iy = hy&0x7fffffff; /* |y| */
41 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
42 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
44 if(x==y) return x; /* x=y, return x */
45 if((ix|lx)==0) { /* x == 0 */
46 INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */
48 if(y==x) return y; else return x; /* raise underflow flag */
50 if(hx>=0) { /* x > 0 */
51 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
54 } else { /* x < y, x += ulp */
59 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
62 } else { /* x > y, x += ulp */
68 if(hy>=0x7ff00000) return x+x; /* overflow */
69 if(hy<0x00100000) { /* underflow */
71 if(y!=x) { /* raise underflow flag */
72 INSERT_WORDS(y,hx,lx);
76 INSERT_WORDS(x,hx,lx);