/*******
 **
 **   To compile:  mc sieve.m -o sieve
 **
 *******/

/**********************************************************************
 **
 **             	Sieve of Eratosthenes
 **
 **	This program implements the Sieve Of Eratosthenes algorithm to
 **	generate prime numbers from a sequence of consecutive natural
 **	numbers [2..N].
 **
 **	The entities used:
 **		(1) driver:	Initiate the program and generate the
 **				sequence of consecutive natural numbers.
 **		(2) sieve:	Each instance of sieve entity stands
 **				for a prime number.
 **
 **     The program terminates when no message is in transit.
 **
 **********************************************************************/
#include "maisie.h"

#define DEFAULT_NUMBER	1000

/**********
 **
 ** DRIVER: 1. Take an command-line argument specifying the maximum 
 **            natural number n. If no argument provided, n=1000 by default.
 **         2. Create the first sieve entity
 **         3. Generate the sequence of consecutive natural numbers and send
 **            to the first sieve.
 **
 **********/ 
entity driver{argc,argv}
   	int argc;
	char **argv;
{	int i, n = DEFAULT_NUMBER;
	ename first;

	if(argc >1)			/* Get the maximum number	*/
	  n = atoi(argv[1]);

	first =  new sieve{ 1 } ; 	/* Create the first entity 	*/
	for(i = 2 ; i <= n; ++i) {	/* Generate the number messages	*/
	  invoke first with number { i};
	}
}


/**********
 **
 ** SIEVE:  The first message contains the prime number
 **		represented by the current instance of sieve entity.
 **
 **		The entity then creates another instance of sieve and
 **		enters a loop. In the loop. the entity accepts all
 **		subsequent numbers from its creator and pass only
 **		those numbers not a multiple of its prime number.
 **
 **********/
entity sieve{myid}
	int myid;				/* For identification	*/
{
	void set_and_print_myprime();		/* Function association	*/
        message number {
	  int number; }	new_number; 		/* Expected message type*/
	ename next_sieve;			/* Child's id		*/
	int my_prime;				/* My prime number	*/

        wait until new_number= mtype(number)	/* First message has 	*/
	  					/*    my prime number	*/
	  set_and_print_myprime(&my_prime);	/* Set myprime		*/
						

	next_sieve =  new sieve{ myid+1 };	/* Create child		*/

	for(;;)
	  wait until {
	    mtype(number)			/* A new number!!	*/
	      if(msg.number.number % my_prime)	/* Multiple of myprime?	*/
	        invoke next_sieve		/* If not, pass to the 	*/
		  with number = msg.number;	/*   the child.		*/
	  }
}

/***
 ***  This function set and print the prime number of the 
 ***       associated entity 'sieve'.
 ***
 ***  Referencing to variables defined in entity 'sieve':
 ***      int myid;
 ***      message number new_number;
 ***      int my_prime;
 ***  
 ***/
void sieve::set_and_print_myprime(my_prime_ptr)
  int *my_prime_ptr;
{
  *my_prime_ptr = new_number.number;
  printf("Sieve number %d is for prime number %d\n",myid, new_number.number);
}