math: add exception handling functionality

According to standards SVID and SYSV.
Modified lgamma calling in case when 'signgam' variable should not be used.

Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/libm/w_pow.c b/libm/w_pow.c
new file mode 100644
index 000000000..411330256
--- /dev/null
+++ b/libm/w_pow.c
@@ -0,0 +1,78 @@
+/* Copyright (C) 2011-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
+
+   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 <math.h>
+#include "math_private.h"
+
+
+/* wrapper pow */
+double
+pow (double x, double y)
+{
+#if __UCLIBC_HAS_FENV__
+	double z = __ieee754_pow (x, y);
+  if (__builtin_expect (!isfinite (z), 0))
+    {
+      if (_LIB_VERSION != _IEEE_)
+	{
+	  if (isnan (x))
+	    {
+	      if (y == 0.0)
+		/* pow(NaN,0.0) */
+		return __kernel_standard (x, y, 42);
+	    }
+	  else if (isfinite (x) && isfinite (y))
+	    {
+	      if (isnan (z))
+		/* pow neg**non-int */
+		return __kernel_standard (x, y, 24);
+	      else if (x == 0.0 && y < 0.0)
+		{
+		  if (signbit (x) && signbit (z))
+		    /* pow(-0.0,negative) */
+		    return __kernel_standard (x, y, 23);
+		  else
+		    /* pow(+0.0,negative) */
+		    return __kernel_standard (x, y, 43);
+		}
+	      else
+		/* pow overflow */
+		return __kernel_standard (x, y, 21);
+	    }
+	}
+    }
+  else if (__builtin_expect (z == 0.0, 0) && isfinite (x) && isfinite (y)
+	   && _LIB_VERSION != _IEEE_)
+    {
+      if (x == 0.0)
+	{
+	  if (y == 0.0)
+	    /* pow(0.0,0.0) */
+	    return __kernel_standard (x, y, 20);
+	}
+      else
+	/* pow underflow */
+	return __kernel_standard (x, y, 22);
+    }
+
+	return z;
+#else
+	return __ieee754_pow (x, y);
+#endif
+}
+libm_hidden_def(pow)