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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.
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_nextafter.c,v 1.8 1995/05/10 20:47:58 jtc Exp $";
#endif
/* IEEE functions
* nextafter(x,y)
* return the next machine floating-point number of x in the
* direction toward y.
* Special cases:
*/
/* Ugly hack so that the aliasing works. */
#define __nexttoward __internal___nexttoward
#define nexttoward __internal_nexttoward
#include <errno.h>
#include <math.h>
#include <math_private.h>
#include <float.h>
#include <libm-alias-double.h>
double __nextafter(double x, double y)
{
int32_t hx,hy,ix,iy;
uint32_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 */
double u;
INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */
u = math_opt_barrier (x);
u = u*u;
math_force_eval (u); /* raise underflow flag */
return x;
}
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) {
double u = x+x; /* overflow */
math_force_eval (u);
__set_errno (ERANGE);
}
if(hy<0x00100000) {
double u = x*x; /* underflow */
math_force_eval (u); /* raise underflow flag */
__set_errno (ERANGE);
}
INSERT_WORDS(x,hx,lx);
return x;
}
libm_alias_double (__nextafter, nextafter)
#ifdef NO_LONG_DOUBLE
strong_alias (__nextafter, __nexttowardl)
weak_alias (__nexttowardl, nexttowardl)
#undef __nexttoward
strong_alias (__nextafter, __nexttoward)
#undef nexttoward
weak_alias (__nextafter, nexttoward)
#endif
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