glibc/sysdeps/ieee754/ldbl-96/s_remquol.c

110 lines
2.3 KiB
C

/* Compute remainder and a congruent to the quotient.
Copyright (C) 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <math.h>
#include "math_private.h"
static const long double zero = 0.0;
long double
__remquol (long double x, long double p, int *quo)
{
int32_t ex,ep,hx,hp;
u_int32_t sx,lx,lp;
int cquo,qs;
GET_LDOUBLE_WORDS (ex, hx, lx, x);
GET_LDOUBLE_WORDS (ep, hp, lp, p);
sx = ex & 0x8000;
qs = (sx ^ (ep & 0x8000)) >> 15;
ep &= 0x7fff;
ex &= 0x7fff;
/* Purge off exception values. */
if ((ep | hp | lp) == 0)
return (x * p) / (x * p); /* p = 0 */
if ((ex == 0x7fff) /* x not finite */
|| ((ep == 0x7fff) /* p is NaN */
&& ((hp | lp) != 0)))
return (x * p) / (x * p);
if (ep <= 0x7ffb)
x = __ieee754_fmodl (x, 8 * p); /* now x < 8p */
if (((ex - ep) | (hx - hp) | (lx - lp)) == 0)
{
*quo = qs ? -1 : 1;
return zero * x;
}
x = fabsl (x);
p = fabsl (p);
cquo = 0;
if (x >= 4 * p)
{
x -= 4 * p;
cquo += 4;
}
if (x >= 2 * p)
{
x -= 2 * p;
cquo += 2;
}
if (ep < 0x0002)
{
if (x + x > p)
{
x -= p;
++cquo;
if (x + x >= p)
{
x -= p;
++cquo;
}
}
}
else
{
long double p_half = 0.5 * p;
if (x > p_half)
{
x -= p;
++cquo;
if (x >= p_half)
{
x -= p;
++cquo;
}
}
}
*quo = qs ? -cquo : cquo;
if (sx)
x = -x;
return x;
}
weak_alias (__remquol, remquol)