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diff --git a/gmp/mpn/generic/toom_eval_pm2exp.c b/gmp/mpn/generic/toom_eval_pm2exp.c
new file mode 100644
index 0000000000..b178fcac24
--- /dev/null
+++ b/gmp/mpn/generic/toom_eval_pm2exp.c
@@ -0,0 +1,128 @@
+/* mpn_toom_eval_pm2exp -- Evaluate a polynomial in +2^k and -2^k
+
+   Contributed to the GNU project by Niels Möller
+
+   THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE.  IT IS ONLY
+   SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS ALMOST
+   GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
+
+Copyright 2009 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 either:
+
+  * 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.
+
+or
+
+  * the GNU General Public License as published by the Free Software
+    Foundation; either version 2 of the License, or (at your option) any
+    later version.
+
+or both in parallel, as here.
+
+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 General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library.  If not,
+see https://www.gnu.org/licenses/.  */
+
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+/* Evaluates a polynomial of degree k > 2, in the points +2^shift and -2^shift. */
+int
+mpn_toom_eval_pm2exp (mp_ptr xp2, mp_ptr xm2, unsigned k,
+		      mp_srcptr xp, mp_size_t n, mp_size_t hn, unsigned shift,
+		      mp_ptr tp)
+{
+  unsigned i;
+  int neg;
+#if HAVE_NATIVE_mpn_addlsh_n
+  mp_limb_t cy;
+#endif
+
+  ASSERT (k >= 3);
+  ASSERT (shift*k < GMP_NUMB_BITS);
+
+  ASSERT (hn > 0);
+  ASSERT (hn <= n);
+
+  /* The degree k is also the number of full-size coefficients, so
+   * that last coefficient, of size hn, starts at xp + k*n. */
+
+#if HAVE_NATIVE_mpn_addlsh_n
+  xp2[n] = mpn_addlsh_n (xp2, xp, xp + 2*n, n, 2*shift);
+  for (i = 4; i < k; i += 2)
+    xp2[n] += mpn_addlsh_n (xp2, xp2, xp + i*n, n, i*shift);
+
+  tp[n] = mpn_lshift (tp, xp+n, n, shift);
+  for (i = 3; i < k; i+= 2)
+    tp[n] += mpn_addlsh_n (tp, tp, xp+i*n, n, i*shift);
+
+  if (k & 1)
+    {
+      cy = mpn_addlsh_n (tp, tp, xp+k*n, hn, k*shift);
+      MPN_INCR_U (tp + hn, n+1 - hn, cy);
+    }
+  else
+    {
+      cy = mpn_addlsh_n (xp2, xp2, xp+k*n, hn, k*shift);
+      MPN_INCR_U (xp2 + hn, n+1 - hn, cy);
+    }
+
+#else /* !HAVE_NATIVE_mpn_addlsh_n */
+  xp2[n] = mpn_lshift (tp, xp+2*n, n, 2*shift);
+  xp2[n] += mpn_add_n (xp2, xp, tp, n);
+  for (i = 4; i < k; i += 2)
+    {
+      xp2[n] += mpn_lshift (tp, xp + i*n, n, i*shift);
+      xp2[n] += mpn_add_n (xp2, xp2, tp, n);
+    }
+
+  tp[n] = mpn_lshift (tp, xp+n, n, shift);
+  for (i = 3; i < k; i+= 2)
+    {
+      tp[n] += mpn_lshift (xm2, xp + i*n, n, i*shift);
+      tp[n] += mpn_add_n (tp, tp, xm2, n);
+    }
+
+  xm2[hn] = mpn_lshift (xm2, xp + k*n, hn, k*shift);
+  if (k & 1)
+    mpn_add (tp, tp, n+1, xm2, hn+1);
+  else
+    mpn_add (xp2, xp2, n+1, xm2, hn+1);
+#endif /* !HAVE_NATIVE_mpn_addlsh_n */
+
+  neg = (mpn_cmp (xp2, tp, n + 1) < 0) ? ~0 : 0;
+
+#if HAVE_NATIVE_mpn_add_n_sub_n
+  if (neg)
+    mpn_add_n_sub_n (xp2, xm2, tp, xp2, n + 1);
+  else
+    mpn_add_n_sub_n (xp2, xm2, xp2, tp, n + 1);
+#else /* !HAVE_NATIVE_mpn_add_n_sub_n */
+  if (neg)
+    mpn_sub_n (xm2, tp, xp2, n + 1);
+  else
+    mpn_sub_n (xm2, xp2, tp, n + 1);
+
+  mpn_add_n (xp2, xp2, tp, n + 1);
+#endif /* !HAVE_NATIVE_mpn_add_n_sub_n */
+
+  /* FIXME: the following asserts are useless if (k+1)*shift >= GMP_LIMB_BITS */
+  ASSERT ((k+1)*shift >= GMP_LIMB_BITS ||
+	  xp2[n] < ((CNST_LIMB(1)<<((k+1)*shift))-1)/((CNST_LIMB(1)<<shift)-1));
+  ASSERT ((k+2)*shift >= GMP_LIMB_BITS ||
+	  xm2[n] < ((CNST_LIMB(1)<<((k+2)*shift))-((k&1)?(CNST_LIMB(1)<<shift):1))/((CNST_LIMB(1)<<(2*shift))-1));
+
+  return neg;
+}