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+/* Copyright (C) 2005, 2006 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <stdbool.h>
+#include <math.h>
+#include <complex.h>
+
+attribute_hidden
+long double _Complex
+__multc3 (long double a, long double b, long double c, long double d)
+{
+ long double ac, bd, ad, bc, x, y;
+
+ ac = a * c;
+ bd = b * d;
+ ad = a * d;
+ bc = b * c;
+
+ x = ac - bd;
+ y = ad + bc;
+
+ if (isnan (x) && isnan (y))
+ {
+ /* Recover infinities that computed as NaN + iNaN. */
+ bool recalc = 0;
+ if (isinf (a) || isinf (b))
+ {
+ /* z is infinite. "Box" the infinity and change NaNs in
+ the other factor to 0. */
+ a = __copysignl (isinf (a) ? 1 : 0, a);
+ b = __copysignl (isinf (b) ? 1 : 0, b);
+ if (isnan (c)) c = __copysignl (0, c);
+ if (isnan (d)) d = __copysignl (0, d);
+ recalc = 1;
+ }
+ if (isinf (c) || isinf (d))
+ {
+ /* w is infinite. "Box" the infinity and change NaNs in
+ the other factor to 0. */
+ c = __copysignl (isinf (c) ? 1 : 0, c);
+ d = __copysignl (isinf (d) ? 1 : 0, d);
+ if (isnan (a)) a = __copysignl (0, a);
+ if (isnan (b)) b = __copysignl (0, b);
+ recalc = 1;
+ }
+ if (!recalc
+ && (isinf (ac) || isinf (bd) || isinf (ad) || isinf (bc)))
+ {
+ /* Recover infinities from overflow by changing NaNs to 0. */
+ if (isnan (a)) a = __copysignl (0, a);
+ if (isnan (b)) b = __copysignl (0, b);
+ if (isnan (c)) c = __copysignl (0, c);
+ if (isnan (d)) d = __copysignl (0, d);
+ recalc = 1;
+ }
+ if (recalc)
+ {
+ x = INFINITY * (a * c - b * d);
+ y = INFINITY * (a * d + b * c);
+ }
+ }
+
+ return x + I * y;
+}