1 files changed, 46 insertions, 0 deletions
diff --git a/libm/w_log2.c b/libm/w_log2.c
new file mode 100644
index 000000000..08433bd0c
--- /dev/null
+++ b/libm/w_log2.c
@@ -0,0 +1,46 @@
+/* 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
+
+/* wrapper log2(x) */
+double
+log2 (double x)
+{
+#if __UCLIBC_HAS_FENV__
+  if (__builtin_expect (islessequal (x, 0.0), 0) && _LIB_VERSION != _IEEE_)
+    {
+      if (x == 0.0)
+	{
+	  feraiseexcept (FE_DIVBYZERO);
+	  return __kernel_standard (x, x, 48); /* log2(0) */
+	}
+      else
+	{
+	  feraiseexcept (FE_INVALID);
+	  return __kernel_standard (x, x, 49); /* log2(x<0) */
+	}
+    }
+#endif /* __UCLIBC_HAS_FENV__ */
+  return  __ieee754_log2 (x);
+}
+libm_hidden_def(log2)