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glibc/math/divtc3.c
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/* Copyright (C) 2005-2016 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 | |
<http://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; | |
} |