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77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson <rth@redhat.com>, 2005.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdbool.h>
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#include <math.h>
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#include <complex.h>
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attribute_hidden
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long double _Complex
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__divtc3 (long double a, long double b, long double c, long double d)
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{
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long double denom, ratio, x, y;
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/* ??? We can get better behavior from logarithmic scaling instead of
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the division. But that would mean starting to link libgcc against
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libm. We could implement something akin to ldexp/frexp as gcc builtins
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fairly easily... */
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if (fabsl (c) < fabsl (d))
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{
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ratio = c / d;
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denom = (c * ratio) + d;
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x = ((a * ratio) + b) / denom;
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y = ((b * ratio) - a) / denom;
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}
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else
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{
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ratio = d / c;
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denom = (d * ratio) + c;
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x = ((b * ratio) + a) / denom;
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y = (b - (a * ratio)) / denom;
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}
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/* Recover infinities and zeros that computed as NaN+iNaN; the only cases
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are nonzero/zero, infinite/finite, and finite/infinite. */
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if (isnan (x) && isnan (y))
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{
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if (denom == 0.0 && (!isnan (a) || !isnan (b)))
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{
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x = copysignl (INFINITY, c) * a;
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y = copysignl (INFINITY, c) * b;
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}
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else if ((isinf (a) || isinf (b))
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&& isfinite (c) && isfinite (d))
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{
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a = copysignl (isinf (a) ? 1 : 0, a);
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b = copysignl (isinf (b) ? 1 : 0, b);
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x = INFINITY * (a * c + b * d);
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y = INFINITY * (b * c - a * d);
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}
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else if ((isinf (c) || isinf (d))
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&& isfinite (a) && isfinite (b))
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{
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c = copysignl (isinf (c) ? 1 : 0, c);
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d = copysignl (isinf (d) ? 1 : 0, d);
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x = 0.0 * (a * c + b * d);
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y = 0.0 * (b * c - a * d);
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}
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}
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return x + I * y;
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}
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