File: [cvs.NetBSD.org] / src / lib / libm / src / s_nextafter.c (download)
Revision 1.14.18.1, Tue Aug 29 15:07:31 2017 UTC (6 years, 7 months ago) by martin
Branch: netbsd-8
CVS Tags: netbsd-8-2-RELEASE, netbsd-8-1-RELEASE, netbsd-8-1-RC1, netbsd-8-0-RELEASE, netbsd-8-0-RC2, netbsd-8-0-RC1, matt-nb8-mediatek-base, matt-nb8-mediatek Changes since 1.14: +2 -1
lines
Also pull up rev 1.15 and 1.16 for ticket #217:
On systems without __HAVE_LONG_DOUBLE, alias nexttoward() to nextafter().
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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.
* ====================================================
*/
#include <sys/cdefs.h>
#if defined(LIBM_SCCS) && !defined(lint)
__RCSID("$NetBSD: s_nextafter.c,v 1.14.18.1 2017/08/29 15:07:31 martin Exp $");
#endif
/* IEEE functions
* nextafter(x,y)
* return the next machine floating-point number of x in the
* direction toward y.
* Special cases:
*/
#include "math.h"
#include "math_private.h"
#ifndef __HAVE_LONG_DOUBLE
__strong_alias(nextafterl, nextafter)
__strong_alias(nexttoward, nextafter)
#endif
double
nextafter(double x, double y)
{
int32_t hx,hy,ix,iy;
u_int32_t lx,ly;
EXTRACT_WORDS(hx,lx,x);
EXTRACT_WORDS(hy,ly,y);
ix = hx&0x7fffffff; /* |x| */
iy = hy&0x7fffffff; /* |y| */
if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
return x+y;
if(x==y) return y; /* x=y, return y */
if((ix|lx)==0) { /* x == 0 */
INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */
y = x*x;
if(y==x) return y; else return x; /* raise underflow flag */
}
if(hx>=0) { /* x > 0 */
if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
if(lx==0) hx -= 1;
lx -= 1;
} else { /* x < y, x += ulp */
lx += 1;
if(lx==0) hx += 1;
}
} else { /* x < 0 */
if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
if(lx==0) hx -= 1;
lx -= 1;
} else { /* x > y, x += ulp */
lx += 1;
if(lx==0) hx += 1;
}
}
hy = hx&0x7ff00000;
if(hy>=0x7ff00000) return x+x; /* overflow */
if(hy<0x00100000) { /* underflow */
y = x*x;
if(y!=x) { /* raise underflow flag */
INSERT_WORDS(y,hx,lx);
return y;
}
}
INSERT_WORDS(x,hx,lx);
return x;
}