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diff --git a/gmp/mpz/gcd.c b/gmp/mpz/gcd.c
new file mode 100644
index 00000000..4fdb48fc
--- /dev/null
+++ b/gmp/mpz/gcd.c
@@ -0,0 +1,163 @@
+/* mpz/gcd.c:   Calculate the greatest common divisor of two integers.
+
+Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2002, 2005 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 3 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.  If not, see http://www.gnu.org/licenses/.  */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+#ifdef BERKELEY_MP
+#include "mp.h"
+#endif
+
+
+void
+#ifndef BERKELEY_MP
+mpz_gcd (mpz_ptr g, mpz_srcptr u, mpz_srcptr v)
+#else /* BERKELEY_MP */
+gcd (mpz_srcptr u, mpz_srcptr v, mpz_ptr g)
+#endif /* BERKELEY_MP */
+{
+  unsigned long int g_zero_bits, u_zero_bits, v_zero_bits;
+  mp_size_t g_zero_limbs, u_zero_limbs, v_zero_limbs;
+  mp_ptr tp;
+  mp_ptr up = u->_mp_d;
+  mp_size_t usize = ABS (u->_mp_size);
+  mp_ptr vp = v->_mp_d;
+  mp_size_t vsize = ABS (v->_mp_size);
+  mp_size_t gsize;
+  TMP_DECL;
+
+  /* GCD(0, V) == V.  */
+  if (usize == 0)
+    {
+      g->_mp_size = vsize;
+      if (g == v)
+	return;
+      if (g->_mp_alloc < vsize)
+	_mpz_realloc (g, vsize);
+      MPN_COPY (g->_mp_d, vp, vsize);
+      return;
+    }
+
+  /* GCD(U, 0) == U.  */
+  if (vsize == 0)
+    {
+      g->_mp_size = usize;
+      if (g == u)
+	return;
+      if (g->_mp_alloc < usize)
+	_mpz_realloc (g, usize);
+      MPN_COPY (g->_mp_d, up, usize);
+      return;
+    }
+
+  if (usize == 1)
+    {
+      g->_mp_size = 1;
+      g->_mp_d[0] = mpn_gcd_1 (vp, vsize, up[0]);
+      return;
+    }
+
+  if (vsize == 1)
+    {
+      g->_mp_size = 1;
+      g->_mp_d[0] = mpn_gcd_1 (up, usize, vp[0]);
+      return;
+    }
+
+  TMP_MARK;
+
+  /*  Eliminate low zero bits from U and V and move to temporary storage.  */
+  while (*up == 0)
+    up++;
+  u_zero_limbs = up - u->_mp_d;
+  usize -= u_zero_limbs;
+  count_trailing_zeros (u_zero_bits, *up);
+  tp = up;
+  up = (mp_ptr) TMP_ALLOC (usize * BYTES_PER_MP_LIMB);
+  if (u_zero_bits != 0)
+    {
+      mpn_rshift (up, tp, usize, u_zero_bits);
+      usize -= up[usize - 1] == 0;
+    }
+  else
+    MPN_COPY (up, tp, usize);
+
+  while (*vp == 0)
+    vp++;
+  v_zero_limbs = vp - v->_mp_d;
+  vsize -= v_zero_limbs;
+  count_trailing_zeros (v_zero_bits, *vp);
+  tp = vp;
+  vp = (mp_ptr) TMP_ALLOC (vsize * BYTES_PER_MP_LIMB);
+  if (v_zero_bits != 0)
+    {
+      mpn_rshift (vp, tp, vsize, v_zero_bits);
+      vsize -= vp[vsize - 1] == 0;
+    }
+  else
+    MPN_COPY (vp, tp, vsize);
+
+  if (u_zero_limbs > v_zero_limbs)
+    {
+      g_zero_limbs = v_zero_limbs;
+      g_zero_bits = v_zero_bits;
+    }
+  else if (u_zero_limbs < v_zero_limbs)
+    {
+      g_zero_limbs = u_zero_limbs;
+      g_zero_bits = u_zero_bits;
+    }
+  else  /*  Equal.  */
+    {
+      g_zero_limbs = u_zero_limbs;
+      g_zero_bits = MIN (u_zero_bits, v_zero_bits);
+    }
+
+  /*  Call mpn_gcd.  The 2nd argument must not have more bits than the 1st.  */
+  vsize = (usize < vsize || (usize == vsize && up[usize-1] < vp[vsize-1]))
+    ? mpn_gcd (vp, vp, vsize, up, usize)
+    : mpn_gcd (vp, up, usize, vp, vsize);
+
+  /*  Here G <-- V << (g_zero_limbs*BITS_PER_MP_LIMB + g_zero_bits).  */
+  gsize = vsize + g_zero_limbs;
+  if (g_zero_bits != 0)
+    {
+      mp_limb_t cy_limb;
+      gsize += (vp[vsize - 1] >> (GMP_NUMB_BITS - g_zero_bits)) != 0;
+      if (g->_mp_alloc < gsize)
+	_mpz_realloc (g, gsize);
+      MPN_ZERO (g->_mp_d, g_zero_limbs);
+
+      tp = g->_mp_d + g_zero_limbs;
+      cy_limb = mpn_lshift (tp, vp, vsize, g_zero_bits);
+      if (cy_limb != 0)
+	tp[vsize] = cy_limb;
+    }
+  else
+    {
+      if (g->_mp_alloc < gsize)
+	_mpz_realloc (g, gsize);
+      MPN_ZERO (g->_mp_d, g_zero_limbs);
+      MPN_COPY (g->_mp_d + g_zero_limbs, vp, vsize);
+    }
+
+  g->_mp_size = gsize;
+  TMP_FREE;
+}