gnu/lib/libgmp/tests/tst-pow_ui.c


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/* Test mpz_abs, mpz_add, mpz_cmp, mpz_cmp_ui, mpz_div, mpz_divmod, mpz_mod,
   mpz_mul.

Copyright (C) 1991, 1993 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 General Public License as published by
the Free Software Foundation; either version 2, 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with the GNU MP Library; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, 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;
{
  MP_INT dividend, divisor;
  MP_INT quotient, remainder;
  MP_INT quotient2, remainder2;
  MP_INT temp;
  mp_size dividend_size, divisor_size;
  int i;
  int reps = 100000;

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

  mpz_init (&dividend);
  mpz_init (&divisor);
  mpz_init (&quotient);
  mpz_init (&remainder);
  mpz_init (&quotient2);
  mpz_init (&remainder2);
  mpz_init (&temp);

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

      divisor_size = urandom () % SIZE - SIZE/2;
      mpz_random2 (&divisor, divisor_size);
      if (mpz_cmp_ui (&divisor, 0) == 0)
	continue;

      exp_size = urandom () % SIZE/2;
      mpz_random2 (&exp, exp_size);

      mpz_powm (&result1, &base, &exp, &divisor);
      mpz_div (&quotient2, &dividend, &divisor);
      mpz_mod (&remainder2, &dividend, &divisor);

      /* First determine that the quotients and remainders computed
	 with different functions are equal.  */
      if (mpz_cmp (&quotient, &quotient2) != 0)
	dump_abort (&dividend, &divisor);
      if (mpz_cmp (&remainder, &remainder2) != 0)
	dump_abort (&dividend, &divisor);

      /* Check if the sign of the quotient is correct.  */
      if (mpz_cmp_ui (&quotient, 0) != 0)
	if ((mpz_cmp_ui (&quotient, 0) < 0)
	    != ((mpz_cmp_ui (&dividend, 0) ^ mpz_cmp_ui (&divisor, 0)) < 0))
	dump_abort (&dividend, &divisor);

      /* Check if the remainder has the same sign as the dividend
	 (quotient rounded towards 0).  */
      if (mpz_cmp_ui (&remainder, 0) != 0)
	if ((mpz_cmp_ui (&remainder, 0) < 0) != (mpz_cmp_ui (&dividend, 0) < 0))
	  dump_abort (&dividend, &divisor);

      mpz_mul (&temp, &quotient, &divisor);
      mpz_add (&temp, &temp, &remainder);
      if (mpz_cmp (&temp, &dividend) != 0)
	dump_abort (&dividend, &divisor);

      mpz_abs (&temp, &divisor);
      mpz_abs (&remainder, &remainder);
      if (mpz_cmp (&remainder, &temp) >= 0)
	dump_abort (&dividend, &divisor);
    }

  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);
}