mirror of
https://sourceware.org/git/glibc.git
synced 2025-11-03 20:53:13 +03:00
96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
/* @(#)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 <math.h>
|
|
#include <math_private.h>
|
|
#include <float.h>
|
|
|
|
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 */
|
|
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) {
|
|
x = x+x; /* overflow */
|
|
if (FLT_EVAL_METHOD != 0 && FLT_EVAL_METHOD != 1)
|
|
asm ("" : "+m"(x));
|
|
return x; /* overflow */
|
|
}
|
|
if(hy<0x00100000) {
|
|
double u = x*x; /* underflow */
|
|
math_force_eval (u); /* raise underflow flag */
|
|
}
|
|
INSERT_WORDS(x,hx,lx);
|
|
return x;
|
|
}
|
|
weak_alias (__nextafter, nextafter)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__nextafter, __nextafterl)
|
|
weak_alias (__nextafter, nextafterl)
|
|
strong_alias (__nextafter, __nexttowardl)
|
|
weak_alias (__nexttowardl, nexttowardl)
|
|
#undef __nexttoward
|
|
strong_alias (__nextafter, __nexttoward)
|
|
#undef nexttoward
|
|
weak_alias (__nextafter, nexttoward)
|
|
#endif
|