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 * ====================================================
14 static char rcsid[] = "$FreeBSD$";
18 * We assume that a long double has a 15-bit exponent. On systems
19 * where long double is the same as double, nexttoward() is an alias
20 * for nextafter(), so we don't use this routine.
27 #include "math_private.h"
29 #if LDBL_MAX_EXP != 0x4000
30 #error "Unsupported long double format"
34 nexttoward(double x, long double y)
41 EXTRACT_WORDS(hx,lx,x);
42 ix = hx&0x7fffffff; /* |x| */
45 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||
46 (uy.bits.exp == 0x7fff &&
47 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
48 return x+y; /* x or y is nan */
49 if(x==y) return (double)y; /* x=y, return y */
51 INSERT_WORDS(x,uy.bits.sign<<31,1); /* return +-minsubnormal */
53 if(t==x) return t; else return x; /* raise underflow flag */
55 if(hx>0.0 ^ x < y) { /* x -= ulp */
58 } else { /* x += ulp */
63 if(ix>=0x7ff00000) return x+x; /* overflow */
64 if(ix<0x00100000) { /* underflow */
66 if(t!=x) { /* raise underflow flag */
67 INSERT_WORDS(y,hx,lx);
71 INSERT_WORDS(x,hx,lx);