1 /* @(#)s_nextafter.c 5.1 93/09/24 */
2 /* $FreeBSD: head/lib/msun/src/s_nexttoward.c 218510 2011-02-10 07:38:13Z das $ */
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 * Developed at SunPro, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
11 * ====================================================
15 * We assume that a long double has a 15-bit exponent. On systems
16 * where long double is the same as double, nexttoward() is an alias
17 * for nextafter(), so we don't use this routine.
24 #include "math_private.h"
26 #if LDBL_MAX_EXP != 0x4000
27 #error "Unsupported long double format"
31 nexttoward(double x, long double y)
38 EXTRACT_WORDS(hx,lx,x);
39 ix = hx&0x7fffffff; /* |x| */
42 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||
43 (uy.bits.exp == 0x7fff &&
44 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
45 return x+y; /* x or y is nan */
46 if(x==y) return (double)y; /* x=y, return y */
48 INSERT_WORDS(x,uy.bits.sign<<31,1); /* return +-minsubnormal */
50 if(t==x) return t; else return x; /* raise underflow flag */
52 if(hx>0.0 ^ x < y) { /* x -= ulp */
55 } else { /* x += ulp */
60 if(ix>=0x7ff00000) return x+x; /* overflow */
61 if(ix<0x00100000) { /* underflow */
63 if(t!=x) { /* raise underflow flag */
64 INSERT_WORDS(x,hx,lx);
68 INSERT_WORDS(x,hx,lx);