add exp10() from glibc

Some software make use of exp10, so add it.
Basic testing with LTP.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/libm/e_exp10.c b/libm/e_exp10.c
new file mode 100644
index 000000000..f0ee87809
--- /dev/null
+++ b/libm/e_exp10.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 1998-2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+   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"
+#include <float.h>
+
+double __ieee754_exp10 (double arg)
+{
+  if (isfinite (arg) && arg < DBL_MIN_10_EXP - DBL_DIG - 10)
+    return DBL_MIN * DBL_MIN;
+  else
+    /* This is a very stupid and inprecise implementation.  It'll get
+       replaced sometime (soon?).  */
+    return __ieee754_exp (M_LN10 * arg);
+}
+strong_alias(__ieee754_exp10, exp10)
+libm_hidden_def(exp10)