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diff --git a/mpfr/cmp_si.c b/mpfr/cmp_si.c
new file mode 100644
index 00000000..9a95b819
--- /dev/null
+++ b/mpfr/cmp_si.c
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+/* mpfr_cmp_si_2exp -- compare a floating-point number with a signed
+machine integer multiplied by a power of 2
+
+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. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+/* returns a positive value if b > i*2^f,
+           a negative value if b < i*2^f,
+           zero if b = i*2^f.
+   b must not be NaN.
+*/
+
+int
+mpfr_cmp_si_2exp (mpfr_srcptr b, long int i, mp_exp_t f)
+{
+  int si;
+
+  si = i < 0 ? -1 : 1; /* sign of i */
+  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (b)))
+    {
+      if (MPFR_IS_INF(b))
+        return MPFR_INT_SIGN(b);
+      else if (MPFR_IS_ZERO(b))
+        return i != 0 ? -si : 0;
+      /* NAN */
+      MPFR_SET_ERANGE ();
+      return 0;
+    }
+  else if (MPFR_SIGN(b) != si || i == 0)
+    return MPFR_INT_SIGN (b);
+  else /* b and i are of same sign si */
+    {
+      mp_exp_t e;
+      unsigned long ai;
+      int k;
+      mp_size_t bn;
+      mp_limb_t c, *bp;
+
+      ai = SAFE_ABS(unsigned long, i);
+
+      /* ai must be representable in a mp_limb_t */
+      MPFR_ASSERTN(ai == (mp_limb_t) ai);
+
+      e = MPFR_GET_EXP (b); /* 2^(e-1) <= b < 2^e */
+      if (e <= f)
+        return -si;
+      if (f < MPFR_EMAX_MAX - BITS_PER_MP_LIMB &&
+          e > f + BITS_PER_MP_LIMB)
+        return si;
+
+      /* now f < e <= f + BITS_PER_MP_LIMB */
+      c = (mp_limb_t) ai;
+      count_leading_zeros(k, c);
+      if ((int) (e - f) > BITS_PER_MP_LIMB - k)
+        return si;
+      if ((int) (e - f) < BITS_PER_MP_LIMB - k)
+        return -si;
+
+      /* now b and i*2^f have the same exponent */
+      c <<= k;
+      bn = (MPFR_PREC(b) - 1) / BITS_PER_MP_LIMB;
+      bp = MPFR_MANT(b);
+      if (bp[bn] > c)
+        return si;
+      if (bp[bn] < c)
+        return -si;
+
+      /* most significant limbs agree, check remaining limbs from b */
+      while (bn > 0)
+        if (bp[--bn])
+          return si;
+      return 0;
+    }
+}
+
+#undef mpfr_cmp_si
+int
+mpfr_cmp_si (mpfr_srcptr b, long int i)
+{
+  return mpfr_cmp_si_2exp (b, i, 0);
+}