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 * ====================================================
15 * return the next machine floating-point number of x in the
21 #include "math_private.h"
24 nextafter(double x, double y)
30 EXTRACT_WORDS(hx,lx,x);
31 EXTRACT_WORDS(hy,ly,y);
32 ix = hx&0x7fffffff; /* |x| */
33 iy = hy&0x7fffffff; /* |y| */
35 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
36 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
38 if(x==y) return y; /* x=y, return y */
39 if((ix|lx)==0) { /* x == 0 */
40 INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */
42 if(t==x) return t; else return x; /* raise underflow flag */
44 if(hx>=0) { /* x > 0 */
45 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
48 } else { /* x < y, x += ulp */
53 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
56 } else { /* x > y, x += ulp */
62 if(hy>=0x7ff00000) return x+x; /* overflow */
63 if(hy<0x00100000) { /* underflow */
65 if(t!=x) { /* raise underflow flag */
66 INSERT_WORDS(y,hx,lx);
70 INSERT_WORDS(x,hx,lx);