2.5-18.1

1 files changed, 75 insertions, 0 deletions

diff --git a/math/divtc3.c b/math/divtc3.c
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+++ b/math/divtc3.c
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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
+__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;
+}