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/* @(#)s_nextafter.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#ifndef lint
static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nextafterl.c,v 1.1 2005/03/07 04:56:46 das Exp $";
#endif
/* IEEE functions
* nextafter(x,y)
* return the next machine floating-point number of x in the
* direction toward y.
* Special cases:
*/
#include <sys/cdefs.h>
#include <float.h>
#include "fpmath.h"
#include "math.h"
#include "math_private.h"
#if LDBL_MAX_EXP != 0x4000
#error "Unsupported long double format"
#endif
long double
nextafterl(long double x, long double y)
{
volatile long double t;
union IEEEl2bits ux, uy;
ux.e = x;
uy.e = y;
if ((ux.bits.exp == 0x7fff &&
((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) ||
(uy.bits.exp == 0x7fff &&
((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
return x+y; /* x or y is nan */
if(x==y) return y; /* x=y, return y */
if(x==0.0) {
ux.bits.manh = 0; /* return +-minsubnormal */
ux.bits.manl = 1;
ux.bits.sign = uy.bits.sign;
t = ux.e*ux.e;
if(t==ux.e) return t; else return ux.e; /* raise underflow flag */
}
if(x>0.0 ^ x<y) { /* x -= ulp */
if(ux.bits.manl==0) {
if ((ux.bits.manh&~LDBL_NBIT)==0)
ux.bits.exp -= 1;
ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT);
}
ux.bits.manl -= 1;
} else { /* x += ulp */
ux.bits.manl += 1;
if(ux.bits.manl==0) {
ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT);
if ((ux.bits.manh&~LDBL_NBIT)==0)
ux.bits.exp += 1;
}
}
if(ux.bits.exp==0x7fff) return x+x; /* overflow */
if(ux.bits.exp==0) { /* underflow */
mask_nbit_l(ux);
t = ux.e * ux.e;
if(t!=ux.e) /* raise underflow flag */
return ux.e;
}
return ux.e;
}
__strong_reference(nextafterl, nexttowardl);
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