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diff --git a/mpfr/mul_2ui.c b/mpfr/mul_2ui.c
new file mode 100644
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+++ b/mpfr/mul_2ui.c
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+/* mpfr_mul_2ui -- multiply a floating-point number by a power of two
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+int
+mpfr_mul_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int n, mp_rnd_t rnd_mode)
+{
+  int inexact;
+
+  MPFR_LOG_FUNC (("x[%#R]=%R n=%lu rnd=%d", x, x, n, rnd_mode),
+                 ("y[%#R]=%R inexact=%d", y, y, inexact));
+
+  inexact = MPFR_UNLIKELY(y != x) ? mpfr_set (y, x, rnd_mode) : 0;
+
+  if (MPFR_LIKELY( MPFR_IS_PURE_FP(y)) )
+    {
+      /* n will have to be casted to long to make sure that the addition
+         and subtraction below (for overflow detection) are signed */
+      while (MPFR_UNLIKELY(n > LONG_MAX))
+        {
+          int inex2;
+
+          n -= LONG_MAX;
+          inex2 = mpfr_mul_2ui(y, y, LONG_MAX, rnd_mode);
+          if (inex2)
+            return inex2; /* overflow */
+        }
+
+      /* MPFR_EMIN_MIN + (long) n is signed and doesn't lead to an overflow;
+         the first test useful so that the real test can't lead to an
+         overflow. */
+      {
+        mp_exp_t exp = MPFR_GET_EXP (y);
+        if (MPFR_UNLIKELY( __gmpfr_emax < MPFR_EMIN_MIN + (long) n ||
+                           exp > __gmpfr_emax - (long) n))
+          return mpfr_overflow (y, rnd_mode, MPFR_SIGN(y));
+
+        MPFR_SET_EXP (y, exp + (long) n);
+      }
+    }
+
+  return inexact;
+}