gen-fib.c

/* Generate Fibonacci table data.

Copyright 2001, 2002, 2004, 2012 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 <stdio.h>
#include "bootstrap.c"

mpz_t  *f;
int    fnum, fib_limit, luc_limit;

void
generate (int numb_bits)
{
  mpz_t  limit, l;
  int    falloc, i;

  mpz_init_set_ui (limit, 1L);
  mpz_mul_2exp (limit, limit, numb_bits);

  /* fib(2n) > 2^n, so use 2n as a limit for the table size */
  falloc = 2 * numb_bits;
  f = xmalloc (falloc * sizeof (*f));

  mpz_init_set_ui (f[0], 1L);  /* F[-1] */
  mpz_init_set_ui (f[1], 0L);  /* F[0] */

  mpz_init (l);

  for (i = 2; ; i++)
    {
      assert (i < falloc);

      /* F[i] = F[i-1] + F[i-2] */
      mpz_init (f[i]);
      mpz_add (f[i], f[i-1], f[i-2]);
      if (mpz_cmp (f[i], limit) >= 0)
        break;

      fnum = i+1;
      fib_limit = i-1;

      /* L[i] = F[i]+2*F[i-1] */
      mpz_add (l, f[i], f[i-1]);
      mpz_add (l, l, f[i-1]);

      if (mpz_cmp (l, limit) < 0)
        luc_limit = i-1;
    }

  mpz_clear (limit);
}


void
header (int numb_bits)
{
  printf ("/* This file generated by gen-fib.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 ("#define FIB_TABLE_LIMIT         %d\n", fib_limit);
  printf ("#define FIB_TABLE_LUCNUM_LIMIT  %d\n", luc_limit);
}

void
table (int numb_bits)
{
  int  i;

  printf ("/* This file generated by gen-fib.c - DO NOT EDIT. */\n");
  printf ("\n");
  printf ("#include \"gmp.h\"\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");
  printf ("const mp_limb_t\n");
  printf ("__gmp_fib_table[FIB_TABLE_LIMIT+2] = {\n");

  for (i = 0; i < fnum; i++)
    {
      printf ("  CNST_LIMB (0x");
      mpz_out_str (stdout, 16, f[i]);
      printf ("),  /* %d */\n", i-1);
    }
  printf ("};\n");
}

int
main (int argc, char *argv[])
{
  int  limb_bits, nail_bits, numb_bits;

  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);
    }
  numb_bits = limb_bits - nail_bits;

  generate (numb_bits);

  if (strcmp (argv[1], "header") == 0)
    header (numb_bits);
  else if (strcmp (argv[1], "table") == 0)
    table (numb_bits);
  else
    {
      fprintf (stderr, "Invalid header/table choice: %s\n", argv[1]);
      exit (1);
    }

  return 0;
}