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/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson <rth@redhat.com>, 2005.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdbool.h>
#include <math.h>
#include <complex.h>
attribute_hidden
long double _Complex
__divtc3 (long double a, long double b, long double c, long double d)
{
long double denom, ratio, x, y;
/* ??? We can get better behavior from logarithmic scaling instead of
the division. But that would mean starting to link libgcc against
libm. We could implement something akin to ldexp/frexp as gcc builtins
fairly easily... */
if (fabsl (c) < fabsl (d))
{
ratio = c / d;
denom = (c * ratio) + d;
x = ((a * ratio) + b) / denom;
y = ((b * ratio) - a) / denom;
}
else
{
ratio = d / c;
denom = (d * ratio) + c;
x = ((b * ratio) + a) / denom;
y = (b - (a * ratio)) / 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 (denom == 0.0 && (!isnan (a) || !isnan (b)))
{
x = copysignl (INFINITY, c) * a;
y = copysignl (INFINITY, c) * b;
}
else if ((isinf (a) || isinf (b))
&& isfinite (c) && isfinite (d))
{
a = copysignl (isinf (a) ? 1 : 0, a);
b = copysignl (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 = copysignl (isinf (c) ? 1 : 0, c);
d = copysignl (isinf (d) ? 1 : 0, d);
x = 0.0 * (a * c + b * d);
y = 0.0 * (b * c - a * d);
}
}
return x + I * y;
}
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