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diff --git a/rts/gmp/mpz/fdiv_r_2exp.c b/rts/gmp/mpz/fdiv_r_2exp.c
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--- /dev/null
+++ b/rts/gmp/mpz/fdiv_r_2exp.c
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+/* mpz_fdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder.
+
+Copyright (C) 1991, 1993, 1994, 1995, 1998, 1999, 2000 Free Software
+Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP 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 MP 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 MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+void
+#if __STDC__
+mpz_fdiv_r_2exp (mpz_ptr res, mpz_srcptr in, unsigned long int cnt)
+#else
+mpz_fdiv_r_2exp (res, in, cnt)
+     mpz_ptr res;
+     mpz_srcptr in;
+     unsigned long int cnt;
+#endif
+{
+  mp_size_t in_size = ABS (in->_mp_size);
+  mp_size_t res_size;
+  mp_size_t limb_cnt = cnt / BITS_PER_MP_LIMB;
+  mp_srcptr in_ptr = in->_mp_d;
+
+  if (in_size > limb_cnt)
+    {
+      /* The input operand is (probably) greater than 2**CNT.  */
+      mp_limb_t x;
+
+      x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % BITS_PER_MP_LIMB) - 1);
+      if (x != 0)
+	{
+	  res_size = limb_cnt + 1;
+	  if (res->_mp_alloc < res_size)
+	    _mpz_realloc (res, res_size);
+
+	  res->_mp_d[limb_cnt] = x;
+	}
+      else
+	{
+	  res_size = limb_cnt;
+	  MPN_NORMALIZE (in_ptr, res_size);
+
+	  if (res->_mp_alloc < res_size)
+	    _mpz_realloc (res, res_size);
+
+	  limb_cnt = res_size;
+	}
+    }
+  else
+    {
+      /* The input operand is smaller than 2**CNT.  We perform a no-op,
+	 apart from that we might need to copy IN to RES, and may need
+	 to round the result.  */
+      res_size = in_size;
+      if (res->_mp_alloc < res_size)
+	_mpz_realloc (res, res_size);
+
+      limb_cnt = res_size;
+    }
+
+  if (res != in)
+    MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt);
+  in_size = in->_mp_size;
+  res->_mp_size = res_size;
+  if (in_size < 0 && res_size != 0)
+    {
+      /* Result should be 2^CNT - RES */
+      mpz_t tmp;
+      TMP_DECL (marker);
+      TMP_MARK (marker);
+      MPZ_TMP_INIT (tmp, cnt/BITS_PER_MP_LIMB + 2);
+      mpz_set_ui (tmp, 1L);
+      mpz_mul_2exp (tmp, tmp, cnt);
+      mpz_sub (res, tmp, res);
+      TMP_FREE (marker);
+    }
+}
+
+/* This is an alternative ending of the above function using just low-level
+   functions.  Tested, but perhaps excessive?  */
+#if 0
+  if (in->_mp_size < 0 && res_size != 0)
+    {
+      /* Result should be 2^CNT - RES */
+
+      mp_ptr rp;
+
+      limb_cnt = cnt / BITS_PER_MP_LIMB;
+
+      if (res->_mp_alloc <= limb_cnt)
+	_mpz_realloc (res, limb_cnt + 1);
+      rp = PTR(res);
+      if (res_size > limb_cnt)
+	{
+	  mpn_nz_neg (rp, rp, res_size);
+	  rp[limb_cnt] &= ~(~(mp_limb_t) 0 << cnt % BITS_PER_MP_LIMB);
+	  MPN_NORMALIZE_NOT_ZERO (rp, res_size);
+	}
+      else
+	{
+	  mp_size_t i;
+	  mpn_nz_neg (rp, rp, res_size);
+	  for (i = res_size; i < limb_cnt; i++)
+	    rp[i] = ~ (mp_limb_t) 0;
+	  res_size = limb_cnt;
+	  if (cnt % BITS_PER_MP_LIMB != 0)
+	    {
+	      rp[res_size] = ((mp_limb_t) 1 << (cnt % BITS_PER_MP_LIMB)) - 1;
+	      res_size++;
+	    }
+	  else
+	    MPN_NORMALIZE_NOT_ZERO (rp, res_size);
+	}
+    }
+  SIZ(res) = res_size;
+}
+
+static void
+mpn_nz_neg (rp, sp, n)
+     mp_ptr rp, sp;
+     mp_size_t n;
+{
+  mp_size_t i;
+  mp_limb_t x;
+
+  x = sp[0];
+  rp[0] = -x;
+  for (i = 1; x == 0; i++)
+    {
+      x = sp[i];
+      rp[i] = -x;
+    }
+
+  for (; i < n; i++)
+    {
+      rp[i] = ~sp[i];
+    }
+}
+#endif