# include <stdbool.h>
# include <stdio.h>
# include <stdlib.h>
# include <time.h>

# include "prime_pi.h"

int main ( );
void prime_pi1_test ( );
void pi_values ( int *n_data, int *n, int *p );
void timestamp ( );

/******************************************************************************/

int main ( )

/******************************************************************************/
/*
  Purpose:

    prime_pi_test() tests prime_pi().

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    31 December 2022

  Author:

    John Burkardt
*/
{
  timestamp ( );
  printf ( "\n" );
  printf ( "prime_pi_test():\n" );
  printf ( "  C version\n" );
  printf ( "  Test prime_pi()\n" );

  prime_pi1_test ( );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "prime_pi_test():\n" );
  printf ( "  Normal end of execution.\n" );
  printf ( "\n" );
  timestamp ( );

  return 0;
}
/******************************************************************************/

void prime_pi1_test ( )

/******************************************************************************/
/*
  Purpose:

    prime_pi1_test() tests prime_pi1().

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    31 December 2022

  Author:

    John Burkardt
*/
{
  int n;
  int n_data;
  int pi1;
  int pi2;

  printf ( "\n" );
  printf ( "prime_pi1_test():\n" );
  printf ( "  Test prime_pi1()\n" );
  printf ( "           n          Pi(n)          prime_pi1(n)\n" );
  printf ( "\n" );

  n_data = 0;

  while ( true )
  {
    pi_values ( &n_data, &n, &pi1 );

    if ( n_data == 0 )
    {
      break;
    }

    pi2 = prime_pi1 ( n );

    printf ( "%12d  %10d  %10d\n", n, pi1, pi2 );

  }

  return;
}
/******************************************************************************/

void pi_values ( int *n_data, int *n, int *p )

/******************************************************************************/
/*
  Purpose:

    pi_values() returns values of the Pi function.

  Discussion:

    Pi[n] is the number of primes less than or equal to n.

    In Mathematica, the function can be evaluated by:

      PrimePi[n]

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    31 December 2022

  Author:

    John Burkardt

  Reference:

    Stephen Wolfram,
    The Mathematica Book,
    Fourth Edition,
    Cambridge University Press, 1999,
    ISBN: 0-521-64314-7,
    LC: QA76.95.W65.

  Input:

    int *N_DATA.  The user sets N_DATA to 0 before the first call.

  Output:

    int *N_DATA.  The routine increments N_DATA by 1, and
    returns the corresponding data; when there is no more data, the
    output value of N_DATA will be 0 again.

    int *N, the argument.

    int *P, the value of the function.
*/
{
# define N_MAX 21

  static int n_vec[N_MAX] = {
            1, 
            2, 
            4, 
            8, 
           16, 
           32, 
           64, 
          128, 
          256, 
          512, 
         1024, 
         2048, 
         4096, 
         8192, 
        16384, 
        32768, 
        65536, 
       131072, 
       262144, 
       524288, 
      1048576 };

  static int p_vec[N_MAX] = {
             0, 
             1, 
             2, 
             4, 
             6, 
            11, 
            18, 
            31, 
            54, 
            97, 
           172, 
           309, 
           564, 
          1028, 
          1900, 
          3512, 
          6542, 
         12251, 
         23000, 
         43390, 
         82025 };

  if ( *n_data < 0 )
  {
    *n_data = 0;
  }

  *n_data = *n_data + 1;

  if ( N_MAX < *n_data )
  {
    *n_data = 0;
    *n = 0;
    *p = 0;
  }
  else
  {
    *n = n_vec[*n_data-1];
    *p = p_vec[*n_data-1];
  }

  return;
# undef N_MAX
}
/******************************************************************************/

void timestamp ( )

/******************************************************************************/
/*
  Purpose:

    timestamp() prints the current YMDHMS date as a time stamp.

  Example:

    17 June 2014 09:45:54 AM

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    01 May 2021

  Author:

    John Burkardt
*/
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct tm *tm;
  time_t now;

  now = time ( NULL );
  tm = localtime ( &now );

  strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm );

  printf ( "%s\n", time_buffer );

  return;
# undef TIME_SIZE
}