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, 47 insertions, 0 deletions

diff --git a/libm/w_log2l.c b/libm/w_log2l.c
new file mode 100644
index 000000000..cbe45ce85
--- /dev/null
+++ b/libm/w_log2l.c
@@ -0,0 +1,47 @@
+/* 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"
+#if __UCLIBC_HAS_FENV__
+#include <fenv.h>
+#endif
+
+#if !defined __NO_LONG_DOUBLE_MATH
+/* wrapper log2l(x) */
+long double
+log2l (long double x)
+{
+# if __UCLIBC_HAS_FENV__
+  if (__builtin_expect (islessequal (x, 0.0L), 0) && _LIB_VERSION != _IEEE_)
+    {
+      if (x == 0.0L)
+	{
+	  feraiseexcept (FE_DIVBYZERO);
+	  return __kernel_standard_l (x, x, 248); /* log2(0) */
+	}
+      else
+	{
+	  feraiseexcept (FE_INVALID);
+	  return __kernel_standard_l (x, x, 249); /* log2(x<0) */
+	}
+    }
+# endif /* __UCLIBC_HAS_FENV__ */
+  return  (long double) __ieee754_log2 ((double) x);
+}
+#endif /* __NO_LONG_DOUBLE_MATH */