1 files changed, 80 insertions, 0 deletions
diff --git a/math/multc3.c b/math/multc3.c
new file mode 100644
index 0000000000..6369f48f24
--- /dev/null
+++ b/math/multc3.c
@@ -0,0 +1,80 @@
+/* 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;
+}