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/* Copyright (C) 1989-2024 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC 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 General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* This is a temporary specialization of code from libgcc/libgcc2.c. */
#include "soft-fp.h"
#include "quad-float128.h"
/* Use the correct built-in function based on whether TFmode is _Float128 or
long double. See quad-float128.h for more details. */
#ifndef __LONG_DOUBLE_IEEE128__
#define COPYSIGN(x,y) __builtin_copysignf128 (x, y)
#define INFINITY __builtin_inff128 ()
#define FABS __builtin_fabsf128
#else
#define COPYSIGN(x,y) __builtin_copysignl (x, y)
#define INFINITY __builtin_infl ()
#define FABS __builtin_fabsl
#endif
#define isnan __builtin_isnan
#define isinf __builtin_isinf
#define isfinite __builtin_isfinite
#if defined(FLOAT128_HW_INSNS) && !defined(__divkc3)
#define __divkc3 __divkc3_sw
#endif
#ifndef __LONG_DOUBLE_IEEE128__
#define RBIG (__LIBGCC_KF_MAX__ / 2)
#define RMIN (__LIBGCC_KF_MIN__)
#define RMIN2 (__LIBGCC_KF_EPSILON__)
#define RMINSCAL (1 / __LIBGCC_KF_EPSILON__)
#define RMAX2 (RBIG * RMIN2)
#else
#define RBIG (__LIBGCC_TF_MAX__ / 2)
#define RMIN (__LIBGCC_TF_MIN__)
#define RMIN2 (__LIBGCC_TF_EPSILON__)
#define RMINSCAL (1 / __LIBGCC_TF_EPSILON__)
#define RMAX2 (RBIG * RMIN2)
#endif
TCtype
__divkc3 (TFtype a, TFtype b, TFtype c, TFtype d)
{
TFtype denom, ratio, x, y;
TCtype res;
/* long double has significant potential underflow/overflow errors that
can be greatly reduced with a limited number of tests and adjustments.
*/
/* Scale by max(c,d) to reduce chances of denominator overflowing. */
if (FABS (c) < FABS (d))
{
/* Prevent underflow when denominator is near max representable. */
if (FABS (d) >= RBIG)
{
a = a / 2;
b = b / 2;
c = c / 2;
d = d / 2;
}
/* Avoid overflow/underflow issues when c and d are small.
Scaling up helps avoid some underflows.
No new overflow possible since c&d < RMIN2. */
if (FABS (d) < RMIN2)
{
a = a * RMINSCAL;
b = b * RMINSCAL;
c = c * RMINSCAL;
d = d * RMINSCAL;
}
else
{
if (((FABS (a) < RMIN) && (FABS (b) < RMAX2) && (FABS (d) < RMAX2))
|| ((FABS (b) < RMIN) && (FABS (a) < RMAX2)
&& (FABS (d) < RMAX2)))
{
a = a * RMINSCAL;
b = b * RMINSCAL;
c = c * RMINSCAL;
d = d * RMINSCAL;
}
}
ratio = c / d;
denom = (c * ratio) + d;
/* Choose alternate order of computation if ratio is subnormal. */
if (FABS (ratio) > RMIN)
{
x = ((a * ratio) + b) / denom;
y = ((b * ratio) - a) / denom;
}
else
{
x = ((c * (a / d)) + b) / denom;
y = ((c * (b / d)) - a) / denom;
}
}
else
{
/* Prevent underflow when denominator is near max representable. */
if (FABS (c) >= RBIG)
{
a = a / 2;
b = b / 2;
c = c / 2;
d = d / 2;
}
/* Avoid overflow/underflow issues when both c and d are small.
Scaling up helps avoid some underflows.
No new overflow possible since both c&d are less than RMIN2. */
if (FABS (c) < RMIN2)
{
a = a * RMINSCAL;
b = b * RMINSCAL;
c = c * RMINSCAL;
d = d * RMINSCAL;
}
else
{
if (((FABS (a) < RMIN) && (FABS (b) < RMAX2) && (FABS (c) < RMAX2))
|| ((FABS (b) < RMIN) && (FABS (a) < RMAX2)
&& (FABS (c) < RMAX2)))
{
a = a * RMINSCAL;
b = b * RMINSCAL;
c = c * RMINSCAL;
d = d * RMINSCAL;
}
}
ratio = d / c;
denom = (d * ratio) + c;
/* Choose alternate order of computation if ratio is subnormal. */
if (FABS (ratio) > RMIN)
{
x = ((b * ratio) + a) / denom;
y = (b - (a * ratio)) / denom;
}
else
{
x = (a + (d * (b / c))) / denom;
y = (b - (d * (a / c))) / denom;
}
}
/* Recover infinities and zeros that computed as NaN+iNaN; the only cases
are nonzero/zero, infinite/finite, and finite/infinite. */
if (isnan (x) && isnan (y))
{
if (c == 0.0 && d == 0.0 && (!isnan (a) || !isnan (b)))
{
x = COPYSIGN (INFINITY, c) * a;
y = COPYSIGN (INFINITY, c) * b;
}
else if ((isinf (a) || isinf (b)) && isfinite (c) && isfinite (d))
{
a = COPYSIGN (isinf (a) ? 1 : 0, a);
b = COPYSIGN (isinf (b) ? 1 : 0, b);
x = INFINITY * (a * c + b * d);
y = INFINITY * (b * c - a * d);
}
else if ((isinf (c) || isinf (d)) && isfinite (a) && isfinite (b))
{
c = COPYSIGN (isinf (c) ? 1 : 0, c);
d = COPYSIGN (isinf (d) ? 1 : 0, d);
x = 0.0 * (a * c + b * d);
y = 0.0 * (b * c - a * d);
}
}
__real__ res = x;
__imag__ res = y;
return res;
}
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