/* Test mpz_powm_ui, mpz_mul. mpz_mod, mpz_mod_ui, mpz_div_ui.

Copyright (C) 1991, 1993, 1994, 1996, 1997 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 <stdio.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "urandom.h"

void debug_mp ();

#ifndef SIZE
#define SIZE 8
#endif

main (argc, argv)
     int argc;
     char **argv;
{
  mpz_t base, mod;
  mpz_t r1, r2, base2;
  mp_size_t base_size, mod_size;
  mp_limb_t exp;
  unsigned long int exp2;
  int i;
  int reps = 10000;

  if (argc == 2)
     reps = atoi (argv[1]);

  mpz_init (base);
  mpz_init (mod);
  mpz_init (r1);
  mpz_init (r2);
  mpz_init (base2);

  for (i = 0; i < reps; i++)
    {
      base_size = urandom () % SIZE /* - SIZE/2 */;
      mpz_random2 (base, base_size);

      mpn_random2 (&exp, 1);

      mod_size = urandom () % SIZE /* - SIZE/2 */;
      mpz_random2 (mod, mod_size);
      if (mpz_cmp_ui (mod, 0) == 0)
	continue;

      /* This is mathematically undefined.  */
      if (mpz_cmp_ui (base, 0) == 0 && exp == 0)
	continue;

#if 0
      putc ('\n', stderr);
      debug_mp (base, -16);
      debug_mp (mod, -16);
#endif

      mpz_powm_ui (r1, base, (unsigned long int) exp, mod);

      mpz_set_ui (r2, 1);
      mpz_set (base2, base);
      exp2 = exp;

      mpz_mod (r2, r2, mod);	/* needed when exp==0 and mod==1 */
      while (exp2 != 0)
	{
	  if (exp2 % 2 != 0)
	    {
	      mpz_mul (r2, r2, base2);
	      mpz_mod (r2, r2, mod);
	    }
	  mpz_mul (base2, base2, base2);
	  mpz_mod (base2, base2, mod);
	  exp2 = exp2 / 2;
	}

#if 0
      debug_mp (r1, -16);
      debug_mp (r2, -16);
#endif

      if (mpz_cmp (r1, r2) != 0)
	abort ();
    }

  exit (0);
}

dump_abort (dividend, divisor)
     MP_INT *dividend, *divisor;
{
  fprintf (stderr, "ERROR\n");
  fprintf (stderr, "dividend = "); debug_mp (dividend, -16);
  fprintf (stderr, "divisor  = "); debug_mp (divisor, -16);
  abort();
}

void
debug_mp (x, base)
     MP_INT *x;
{
  mpz_out_str (stderr, base, x); fputc ('\n', stderr);
}
