//*******************************************************************
// /opt/perf/examples/arm/jprimenumbers.java
//
// This java program provides an example of how a simple program might
// make use of the ARM java wrappers.
// The program will prompt the user for a prime number, then will
// surround the calculation with an arm_start/arm_stop call.  The
// program will output whether the number was prime and the response
// time for the transaction.
//
// Some numbers which will make this think for a while include:
// 27106269116713 (about 18 seconds), 16666666666666661 (about 515 seconds)
//
// Hewlett-Packard Performance Technology Center 11JAN01

import armapi.*;
import java.io.*;
import java.lang.NumberFormatException;
import java.lang.Thread;

public class jprimenumbers {

    public static void main(String[] args) throws Exception
    {

      //
      // Initialize ARM with application and transaction IDs
      //
      ARMApplication armapp = new ARMApplication("Prime_numbers","*");
      ARMTransaction Tran = armapp.createTransaction("Prime_Nums");
      ARMTransactionInstance traninstance = Tran.createTransactionInstance();

      boolean continuing_process = true;   // always true
      InputStreamReader input = new InputStreamReader(System.in);
      BufferedReader buf = new BufferedReader(input);
      String Prime_candidate = new String();

      while ( continuing_process )
      {
        long factor = 3;       //current factor being searched
        long candidateprime;   //number input by user
        long factorlimit;      //high water for factor to search
        long current_time, start_time;  //holds time values in millisecs
        int elapsed_millisecs; //start minus current time
        boolean factorfound = false;  //flag to terminate search

        System.out.print("Please enter a number (1 to exit): ");

        Prime_candidate = buf.readLine();
        candidateprime = Long.parseLong(Prime_candidate);

        //transaction instance begins once a number has been entered by the user
        // start transaction instance
        traninstance.startTran();

        //start timing
        elapsed_millisecs = 0;
        start_time = System.currentTimeMillis();

        // Check for exit requested:
        if (candidateprime == 1)
        {
          System.out.println("exiting.\n");
          traninstance.stopTranInstance(ARMConstants.ARM_ABORT);
          System.exit(0);
        }

        // check to see if reasonable number was input:
        if ( candidateprime <= 0 || candidateprime %2 ==0 )
        {
          System.out.println("Please enter a positive, odd number.\n");
          traninstance.stopTranInstance(ARMConstants.ARM_ABORT);
        }
        else
        {

        // The prime candidate was a reasonable number, so we'll start
        // looking for factors starting from 3 and going up to the
        // square root of the candidate.

        System.out.println();

        factorlimit = (long)java.lang.Math.sqrt(candidateprime);

        while( (factor <= factorlimit) && (factorfound == false) )
        {

          // track current (and thus elapsed milliseconds
          current_time = System.currentTimeMillis();
          elapsed_millisecs = (int)(current_time - start_time);

          // check to see if we're finished
          if ( (candidateprime % factor) == 0 ) {
          factorfound = true;
        }
        else {  // factor does not divide into candidate, continue search:
        factor = factor +2;
        }  //end else

      }  // end while searching for factor

      // After exiting from the while loop, print result
      if ( factorfound == false )
      {
        System.out.println(candidateprime  + " is a prime number.");
      }
      else
      {
        System.out.println(candidateprime + " is NOT a prime number.");
        System.out.println(candidateprime + " / " + factor + " = " +
                                    candidateprime / factor);
      }

      traninstance.stopTranInstance(ARMConstants.ARM_GOOD);
      System.out.println("Transaction time: " +
                                elapsed_millisecs / 1000.0 + " seconds.\n");

      } // end of else good number

    } // end of never-ending while loop

  } // end of main

} // end of class jprimenumbers