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, 86 insertions, 0 deletions

diff --git a/libm/w_scalb.c b/libm/w_scalb.c
new file mode 100644
index 000000000..c4cecc322
--- /dev/null
+++ b/libm/w_scalb.c
@@ -0,0 +1,86 @@
+/* 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 <errno.h>
+
+static double
+__attribute__ ((noinline))
+sysv_scalb (double x, double fn)
+{
+  double z = __ieee754_scalb (x, fn);
+
+  if (__builtin_expect (isinf (z), 0))
+    {
+      if (isfinite (x))
+	return __kernel_standard (x, fn, 32); /* scalb overflow */
+      else
+	__set_errno (ERANGE);
+    }
+  else if (__builtin_expect (z == 0.0, 0) && z != x)
+    return __kernel_standard (x, fn, 33); /* scalb underflow */
+
+  return z;
+}
+#endif /* __UCLIBC_HAS_FENV__ */
+
+/* Here might be a check like "#if defined __UCLIBC_SUSV3_LEGACY__"
+ * but because there is a sysv_scalb() func, it was decided
+ * not to check yhis macro.
+ */
+
+/* Wrapper scalb */
+double
+scalb (double x, double fn)
+{
+#if __UCLIBC_HAS_FENV__
+  if (__builtin_expect (_LIB_VERSION == _SVID_,0))
+    return sysv_scalb (x, fn);
+  else
+    {
+      double z = __ieee754_scalb (x, fn);
+
+      if (__builtin_expect (!isfinite (z) || z == 0.0, 0))
+	{
+	  if (isnan (z))
+	    {
+	      if (!isnan (x) && !isnan (fn))
+		__set_errno (EDOM);
+	    }
+	  else if (isinf (z))
+	    {
+	      if (!isinf (x) && !isinf (fn))
+		__set_errno (ERANGE);
+	    }
+	  else
+	    {
+	      /* z == 0.  */
+	      if (x != 0.0 && !isinf (fn))
+		__set_errno (ERANGE);
+	    }
+	}
+      return z;
+    }
+#else
+  return __ieee754_scalb (x, fn);
+#endif /* __UCLIBC_HAS_FENV__ */
+}
+libm_hidden_def(scalb)