/* Exercise mpz_bin_ui and mpz_bin_uiui.

Copyright 2000, 2001, 2010, 2012 Free Software Foundation, Inc.

This file is part of the GNU MP Library test suite.

The GNU MP Library test suite 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 3 of the License,

or (at your option) any later version.

The GNU MP Library test suite 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 test suite.  If not, see https://www.gnu.org/licenses/.  */

#include <stdio.h>

#include <stdlib.h>

#include "gmp.h"

#include "gmp-impl.h"

#include "tests.h"

/* Default number of generated tests. */

#define COUNT 700

void

try_mpz_bin_ui (mpz_srcptr want, mpz_srcptr n, unsigned long k)

{

  mpz_t  got;

  mpz_init (got);

  mpz_bin_ui (got, n, k);

  MPZ_CHECK_FORMAT (got);

  if (mpz_cmp (got, want) != 0)

    {

      printf ("mpz_bin_ui wrong\n");

      printf ("  n="); mpz_out_str (stdout, 10, n); printf ("\n");

      printf ("  k=%lu\n", k);

      printf ("  got="); mpz_out_str (stdout, 10, got); printf ("\n");

      printf ("  want="); mpz_out_str (stdout, 10, want); printf ("\n");

      abort();

    }

  mpz_clear (got);

}

void

try_mpz_bin_uiui (mpz_srcptr want, unsigned long n, unsigned long k)

{

  mpz_t  got;

  mpz_init (got);

  mpz_bin_uiui (got, n, k);

  MPZ_CHECK_FORMAT (got);

  if (mpz_cmp (got, want) != 0)

    {

      printf ("mpz_bin_uiui wrong\n");

      printf ("  n=%lu\n", n);

      printf ("  k=%lu\n", k);

      printf ("  got="); mpz_out_str (stdout, 10, got); printf ("\n");

      printf ("  want="); mpz_out_str (stdout, 10, want); printf ("\n");

      abort();

    }

  mpz_clear (got);

}

void

samples (void)

{

  static const struct {

    const char     *n;

    unsigned long  k;

    const char     *want;

  } data[] = {

    {   "0", 123456, "0" },

    {   "1", 543210, "0" },

    {   "2", 123321, "0" },

    {   "3", 234567, "0" },

    {   "10", 23456, "0" },

    /* negatives, using bin(-n,k)=bin(n+k-1,k) */

    {   "-1",  0,  "1"  },

    {   "-1",  1, "-1"  },

    {   "-1",  2,  "1"  },

    {   "-1",  3, "-1"  },

    {   "-1",  4,  "1"  },

    {   "-2",  0,  "1"  },

    {   "-2",  1, "-2"  },

    {   "-2",  2,  "3"  },

    {   "-2",  3, "-4"  },

    {   "-2",  4,  "5"  },

    {   "-2",  5, "-6"  },

    {   "-2",  6,  "7"  },

    {   "-3",  0,   "1"  },

    {   "-3",  1,  "-3"  },

    {   "-3",  2,   "6"  },

    {   "-3",  3, "-10"  },

    {   "-3",  4,  "15"  },

    {   "-3",  5, "-21"  },

    {   "-3",  6,  "28"  },

    /* A few random values */

    {   "41", 20,  "269128937220" },

    {   "62", 37,  "147405545359541742" },

    {   "50", 18,  "18053528883775" },

    {  "149", 21,  "19332950844468483467894649" },

  };

  mpz_t  n, want;

  int    i;

  mpz_init (n);

  mpz_init (want);

  for (i = 0; i < numberof (data); i++)

    {

      mpz_set_str_or_abort (n, data[i].n, 0);

      mpz_set_str_or_abort (want, data[i].want, 0);

      try_mpz_bin_ui (want, n, data[i].k);

      if (mpz_fits_ulong_p (n))

	try_mpz_bin_uiui (want, mpz_get_ui (n), data[i].k);

    }

  mpz_clear (n);

  mpz_clear (want);

}

/* Test some bin(2k,k) cases.  This produces some biggish numbers to

   exercise the limb accumulating code.  */

void

twos (int count)

{

  mpz_t          n, want;

  unsigned long  k;

  mpz_init (n);

  mpz_init (want);

  mpz_set_ui (want, (unsigned long) 2);

  for (k = 1; k < count; k++)

    {

      mpz_set_ui (n, 2*k);

      try_mpz_bin_ui (want, n, k);

      try_mpz_bin_uiui (want, 2*k, k);

      mpz_mul_ui (want, want, 2*(2*k+1));

      mpz_fdiv_q_ui (want, want, k+1);

    }

  mpz_clear (n);

  mpz_clear (want);

}

/* Test some random bin(n,k) cases.  This produces some biggish

   numbers to exercise the limb accumulating code.  */

void

randomwalk (int count)

{

  mpz_t          n_z, want;

  unsigned long  n, k, i, r;

  int            tests;

  gmp_randstate_ptr rands;

  rands = RANDS;

  mpz_init (n_z);

  mpz_init (want);

  k = 3;

  n = 12;

  mpz_set_ui (want, (unsigned long) 220); /* binomial(12,3) = 220 */

  for (tests = 1; tests < count; tests++)

    {

      r = gmp_urandomm_ui (rands, 62) + 1;

      for (i = r & 7; i > 0; i--)

	{

	  n++; k++;

	  mpz_mul_ui (want, want, n);

	  mpz_fdiv_q_ui (want, want, k);

	}

      for (i = r >> 3; i > 0; i--)

	{

	  n++;

	  mpz_mul_ui (want, want, n);

	  mpz_fdiv_q_ui (want, want, n - k);

	}

      mpz_set_ui (n_z, n);

      try_mpz_bin_ui (want, n_z, k);

      try_mpz_bin_uiui (want, n, k);

    }

  mpz_clear (n_z);

  mpz_clear (want);

}

/* Test all bin(n,k) cases, with 0 <= k <= n + 1 <= count.  */

void

smallexaustive (unsigned int count)

{

  mpz_t          n_z, want;

  unsigned long  n, k;

  mpz_init (n_z);

  mpz_init (want);

  for (n = 0; n < count; n++)

    {

      mpz_set_ui (want, (unsigned long) 1);

      mpz_set_ui (n_z, n);

      for (k = 0; k <= n; k++)

	{

	  try_mpz_bin_ui (want, n_z, k);

	  try_mpz_bin_uiui (want, n, k);

	  mpz_mul_ui (want, want, n - k);

	  mpz_fdiv_q_ui (want, want, k + 1);

	}

      try_mpz_bin_ui (want, n_z, k);

      try_mpz_bin_uiui (want, n, k);

    }

  mpz_clear (n_z);

  mpz_clear (want);

}

int

main (int argc, char **argv)

{

  int count;

  if (argc > 1)

    {

      char *end;

      count = strtol (argv[1], &end, 0);

      if (*end || count <= 0)

	{

	  fprintf (stderr, "Invalid test count: %s.\n", argv[1]);

	  return 1;

	}

    }

  else

    count = COUNT;

  tests_start ();

  samples ();

  smallexaustive (count >> 4);

  twos (count >> 1);

  randomwalk (count - (count >> 1));

  tests_end ();

  exit (0);

}