diff --git a/third_party/gmp/gen-bases.c b/third_party/gmp/gen-bases.c
new file mode 100644
index 0000000..5f5e7ed
--- /dev/null
+++ b/third_party/gmp/gen-bases.c
@@ -0,0 +1,265 @@
+/* Generate mp_bases data.
+
+Copyright 1991, 1993, 1994, 1996, 2000, 2002, 2004, 2011, 2012,
+2015-2018 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 "bootstrap.c"
+
+
+int    chars_per_limb;
+int    big_base_ctz;
+mpz_t  big_base;
+int    normalization_steps;
+mpz_t  big_base_inverted;
+mpz_t  big_base_binverted;
+
+mpz_t  t;
+
+#define POW2_P(n)  (((n) & ((n) - 1)) == 0)
+
+unsigned int
+ulog2 (unsigned int x)
+{
+  unsigned int i;
+  for (i = 0;  x != 0;  i++)
+    x >>= 1;
+  return i;
+}
+
+void
+binvert (int numb_bits)
+{
+  mpz_t bbo;
+
+  mpz_init_set (bbo, big_base);
+  big_base_ctz = mpz_make_odd (bbo);
+  mpz_invert_2exp (big_base_binverted, bbo, numb_bits);
+}
+
+void
+generate (int limb_bits, int nail_bits, int base)
+{
+  int  numb_bits = limb_bits - nail_bits;
+
+  mpz_set_ui (t, 1L);
+  mpz_mul_2exp (t, t, numb_bits);
+  mpz_set_ui (big_base, (long) base);
+  chars_per_limb = 0;
+  while (mpz_cmp (big_base, t) <= 0)
+    {
+      mpz_mul_ui (big_base, big_base, (long) base);
+      chars_per_limb++;
+    }
+
+  mpz_ui_pow_ui (big_base, (long) base, (long) chars_per_limb);
+
+  normalization_steps = limb_bits - mpz_sizeinbase (big_base, 2);
+
+  mpz_set_ui (t, 1L);
+  mpz_mul_2exp (t, t, 2*limb_bits - normalization_steps);
+  mpz_tdiv_q (big_base_inverted, t, big_base);
+  mpz_clrbit (big_base_inverted, limb_bits);
+
+  binvert (numb_bits);
+}
+
+void
+header (int limb_bits, int nail_bits)
+{
+  int  numb_bits = limb_bits - nail_bits;
+
+  generate (limb_bits, nail_bits, 10);
+
+  printf ("/* This file generated by gen-bases.c - DO NOT EDIT. */\n");
+  printf ("\n");
+  printf ("#if GMP_NUMB_BITS != %d\n", numb_bits);
+  printf ("Error, error, this data is for %d bits\n", numb_bits);
+  printf ("#endif\n");
+  printf ("\n");
+  printf ("/* mp_bases[10] data, as literal values */\n");
+  printf ("#define MP_BASES_CHARS_PER_LIMB_10      %d\n", chars_per_limb);
+  printf ("#define MP_BASES_BIG_BASE_CTZ_10        %d\n", big_base_ctz);
+  printf ("#define MP_BASES_BIG_BASE_10            CNST_LIMB(0x");
+  mpz_out_str (stdout, 16, big_base);
+  printf (")\n");
+  printf ("#define MP_BASES_BIG_BASE_INVERTED_10   CNST_LIMB(0x");
+  mpz_out_str (stdout, 16, big_base_inverted);
+  printf (")\n");
+  printf ("#define MP_BASES_BIG_BASE_BINVERTED_10  CNST_LIMB(0x");
+  mpz_out_str (stdout, 16, big_base_binverted);
+  printf (")\n");
+  printf ("#define MP_BASES_NORMALIZATION_STEPS_10 %d\n", normalization_steps);
+}
+
+
+#define EXTRA 16
+
+/* Compute log(2)/log(b) as a fixnum. */
+void
+mp_2logb (mpz_t r, int bi, int prec)
+{
+  mpz_t t, t2, two, b;
+  int i;
+
+  mpz_init (t);
+  mpz_setbit (t, prec + EXTRA);
+
+  mpz_init (t2);
+
+  mpz_init (two);
+  mpz_setbit (two, prec + EXTRA + 1);
+
+  mpz_set_ui (r, 0);
+
+  mpz_init_set_ui (b, bi);
+  mpz_mul_2exp (b, b, prec+EXTRA);
+
+  for (i = prec-1; i >= 0; i--)
+    {
+      mpz_mul_2exp (b, b, prec+EXTRA);
+      mpz_sqrt (b, b);
+
+      mpz_mul (t2, t, b);
+      mpz_tdiv_q_2exp (t2, t2, prec+EXTRA);
+
+      if (mpz_cmp (t2, two) < 0)	/* not too large? */
+	{
+	  mpz_setbit (r, i);		/* set next less significant bit */
+	  mpz_swap (t, t2);		/* new value acceptable */
+	}
+    }
+
+  mpz_clear (t);
+  mpz_clear (t2);
+  mpz_clear (two);
+  mpz_clear (b);
+}
+
+void
+table (int limb_bits, int nail_bits)
+{
+  int  numb_bits = limb_bits - nail_bits;
+  int  base;
+  mpz_t r, t, logb2, log2b;
+
+  mpz_init (r);
+  mpz_init (t);
+  mpz_init (logb2);
+  mpz_init (log2b);
+
+  printf ("/* This file generated by gen-bases.c - DO NOT EDIT. */\n");
+  printf ("\n");
+  printf ("#include \"gmp-impl.h\"\n");
+  printf ("\n");
+  printf ("#if GMP_NUMB_BITS != %d\n", numb_bits);
+  printf ("Error, error, this data is for %d bits\n", numb_bits);
+  printf ("#endif\n");
+  printf ("\n");
+  puts ("const struct bases mp_bases[257] =\n{");
+  puts ("  /*   0 */ { 0, 0, 0, 0, 0 },");
+  puts ("  /*   1 */ { 0, 0, 0, 0, 0 },");
+  for (base = 2; base <= 256; base++)
+    {
+      generate (limb_bits, nail_bits, base);
+      mp_2logb (r, base, limb_bits + 8);
+      mpz_tdiv_q_2exp (logb2, r, 8);
+      mpz_set_ui (t, 1);
+      mpz_mul_2exp (t, t, 2*limb_bits + 5);
+      mpz_sub_ui (t, t, 1);
+      mpz_add_ui (r, r, 1);
+      mpz_tdiv_q (log2b, t, r);
+
+      printf ("  /* %3u */ { ", base);
+      if (POW2_P (base))
+	{
+          mpz_set_ui (big_base, ulog2 (base) - 1);
+	  mpz_set_ui (big_base_inverted, 0);
+	}
+
+      printf ("%u,", chars_per_limb);
+      printf (" CNST_LIMB(0x");
+      mpz_out_str (stdout, 16, logb2);
+      printf ("), CNST_LIMB(0x");
+      mpz_out_str (stdout, 16, log2b);
+      printf ("), CNST_LIMB(0x");
+      mpz_out_str (stdout, 16, big_base);
+      printf ("), CNST_LIMB(0x");
+      mpz_out_str (stdout, 16, big_base_inverted);
+      printf (") },\n");
+    }
+
+  puts ("};");
+
+  mpz_clear (r);
+  mpz_clear (t);
+  mpz_clear (logb2);
+  mpz_clear (log2b);
+
+}
+
+int
+main (int argc, char **argv)
+{
+  int  limb_bits, nail_bits;
+
+  mpz_init (big_base);
+  mpz_init (big_base_inverted);
+  mpz_init (big_base_binverted);
+  mpz_init (t);
+
+  if (argc != 4)
+    {
+      fprintf (stderr, "Usage: gen-bases <header|table> <limbbits> <nailbits>\n");
+      exit (1);
+    }
+
+  limb_bits = atoi (argv[2]);
+  nail_bits = atoi (argv[3]);
+
+  if (limb_bits <= 0
+      || nail_bits < 0
+      || nail_bits >= limb_bits)
+    {
+      fprintf (stderr, "Invalid limb/nail bits: %d %d\n",
+               limb_bits, nail_bits);
+      exit (1);
+    }
+
+  if (strcmp (argv[1], "header") == 0)
+    header (limb_bits, nail_bits);
+  else if (strcmp (argv[1], "table") == 0)
+    table (limb_bits, nail_bits);
+  else
+    {
+      fprintf (stderr, "Invalid header/table choice: %s\n", argv[1]);
+      exit (1);
+    }
+
+  return 0;
+}