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/* $NetBSD: s_nextafterl.c,v 1.5 2014/01/31 19:38:47 matt Exp $ */
/* @(#)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.
* ====================================================
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: s_nextafterl.c,v 1.5 2014/01/31 19:38:47 matt Exp $");
#include <float.h>
#include <math.h>
#include <machine/ieee.h>
#ifdef __HAVE_LONG_DOUBLE
#ifdef EXT_EXP_INFNAN
#if LDBL_MAX_EXP != 0x4000
#error "Unsupported long double format"
#endif
#ifdef LDBL_IMPLICIT_NBIT
#define LDBL_NBIT 0
#endif
/*
* IEEE functions
* nextafterl(x,y)
* return the next machine floating-point number of x in the
* direction toward y.
* Special cases:
* If x == y, y shall be returned
* If x or y is NaN, a NaN shall be returned
*/
long double
nextafterl(long double x, long double y)
{
volatile long double t;
union ieee_ext_u ux, uy;
ux.extu_ld = x;
uy.extu_ld = y;
if ((ux.extu_exp == EXT_EXP_INFNAN &&
((ux.extu_frach &~ LDBL_NBIT)|ux.extu_fracl) != 0) ||
(uy.extu_exp == EXT_EXP_INFNAN &&
((uy.extu_frach &~ LDBL_NBIT)|uy.extu_fracl) != 0))
return x+y; /* x or y is nan */
if (x == y) return y; /* x=y, return y */
if (x == 0.0) {
ux.extu_frach = 0; /* return +-minsubnormal */
ux.extu_fracl = 1;
ux.extu_sign = uy.extu_sign;
t = ux.extu_ld * ux.extu_ld;
if (t == ux.extu_ld)
return t;
else
return ux.extu_ld; /* raise underflow flag */
}
if ((x>0.0) ^ (x<y)) { /* x -= ulp */
if (ux.extu_fracl == 0) {
if ((ux.extu_frach & ~LDBL_NBIT) == 0)
ux.extu_exp -= 1;
ux.extu_frach = (ux.extu_frach - 1) |
(ux.extu_frach & LDBL_NBIT);
}
ux.extu_fracl -= 1;
} else { /* x += ulp */
ux.extu_fracl += 1;
if (ux.extu_fracl == 0) {
ux.extu_frach = (ux.extu_frach + 1) |
(ux.extu_frach & LDBL_NBIT);
if ((ux.extu_frach & ~LDBL_NBIT) == 0)
ux.extu_exp += 1;
}
}
if (ux.extu_exp == EXT_EXP_INFNAN)
return x+x; /* overflow */
if (ux.extu_exp == 0) { /* underflow */
#ifndef LDBL_IMPLICIT_NBIT
mask_nbit_l(ux);
#endif
t = ux.extu_ld * ux.extu_ld;
if (t != ux.extu_ld) /* raise underflow flag */
return ux.extu_ld;
}
return ux.extu_ld;
}
#endif
#endif /* __HAVE_LONG_DOUBLE */
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