glibc/sysdeps/i386/fpu/s_nextafterl.c
Ulrich Drepper a439bb2fa3 Update.
* sysdeps/i386/fpu/s_nextafterl.c: Decrement high word of mantissa
	of demorm correctly if low word is zero.
	Reported by Fred J. Tydeman <tydeman@tybor.com>.
2003-02-15 05:25:17 +00:00

125 lines
3.0 KiB
C

/* s_nextafterl.c -- long double version of s_nextafter.c.
* Special version for i387.
* Conversion to long double by Ulrich Drepper,
* Cygnus Support, drepper@cygnus.com.
*/
/*
* ====================================================
* 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: $";
#endif
/* IEEE functions
* nextafterl(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"
#ifdef __STDC__
long double __nextafterl(long double x, long double y)
#else
long double __nextafterl(x,y)
long double x,y;
#endif
{
u_int32_t hx,hy,ix,iy;
u_int32_t lx,ly;
int32_t esx,esy;
GET_LDOUBLE_WORDS(esx,hx,lx,x);
GET_LDOUBLE_WORDS(esy,hy,ly,y);
ix = esx&0x7fff; /* |x| */
iy = esy&0x7fff; /* |y| */
/* Intel's extended format has the normally implicit 1 explicit
present. Sigh! */
if(((ix==0x7fff)&&(((hx&0x7fffffff)|lx)!=0)) || /* x is nan */
((iy==0x7fff)&&(((hy&0x7fffffff)|ly)!=0))) /* y is nan */
return x+y;
if(x==y) return y; /* x=y, return y */
if((ix|hx|lx)==0) { /* x == 0 */
SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
y = x*x;
if(y==x) return y; else return x; /* raise underflow flag */
}
if(esx>=0) { /* x > 0 */
if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
/* x > y, x -= ulp */
if(lx==0) {
if (hx <= 0x80000000) {
if (esx == 0) {
--hx;
} else {
esx -= 1;
hx = hx - 1;
if (esx > 0)
hx |= 0x80000000;
}
} else
hx -= 1;
}
lx -= 1;
} else { /* x < y, x += ulp */
lx += 1;
if(lx==0) {
hx += 1;
if (hx==0 || (esx == 0 && hx == 0x80000000)) {
esx += 1;
hx |= 0x80000000;
}
}
}
} else { /* x < 0 */
if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
/* x < y, x -= ulp */
if(lx==0) {
if (hx <= 0x80000000) {
esx -= 1;
hx = hx - 1;
if ((esx&0x7fff) > 0)
hx |= 0x80000000;
} else
hx -= 1;
}
lx -= 1;
} else { /* x > y, x += ulp */
lx += 1;
if(lx==0) {
hx += 1;
if (hx==0 || (esx == 0xffff8000 && hx == 0x80000000)) {
esx += 1;
hx |= 0x80000000;
}
}
}
}
esy = esx&0x7fff;
if(esy==0x7fff) return x+x; /* overflow */
if(esy==0) { /* underflow */
y = x*x;
if(y!=x) { /* raise underflow flag */
SET_LDOUBLE_WORDS(y,esx,hx,lx);
return y;
}
}
SET_LDOUBLE_WORDS(x,esx,hx,lx);
return x;
}
weak_alias (__nextafterl, nextafterl)
strong_alias (__nextafterl, __nexttowardl)
weak_alias (__nextafterl, nexttowardl)