/* Use csbackup.joensuu.fi instead of cs

   compile: /usr/local/mpich-1.2.0/bin/mpicc ds.ex2.7.skel.c
   run : /usr/local/mpich-1.2.0/bin/mpirun -np 5 a.out

   To understand the program, draw the processors and slowly draw each
   message.

7) Implement your solution to exercise 3 using C, MPI, and ready communication macros from the course examples page. Here, participants are MPI processes, time list is a bit array, and communication is done with Send/Receive -macros. For simplicity, you may assume that only 1 hour reservation is needed, scope of time is one day (24h), and PID 0 starts the negotiation.

*/
   
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

/* a variable needeed for call, result not used */
static MPI_Status tmpstat;

/* logical directions */
#define Left (PID-1)
#define Right (PID+1)
#define Any MPI_ANY_SOURCE

/* Send and Receive operations
   DEST & SOURCE can be Left/Right or a PID (int 0..P-1)
   SOURCE can be Any

   Thes are actually non-blocking at cs, even if the MPI-standard 
   would require these to be assumed blocking 
   Thus: you can do, e.g., send(left), send(right), recv(left), recv(right)

   Hint on printing: pipe the output of the program to sort
   /usr/local/mpich-1.2.0/bin/mpirun -np 5 a.out | sort
*/

/* Send the value of an int _variable_ VAR to destination process DEST */
#define Send(DEST, VAR) MPI_Send(&VAR, 1, MPI_INT, DEST, 0, MPI_COMM_WORLD)

/* Receive an integer to an int variable VAR from destination process SOURCE */
#define Receive(SOURCE, VAR) MPI_Recv(&VAR, 1, MPI_INT, SOURCE, 0, MPI_COMM_WORLD, &tmpstat)

#define PRINT 1

#define DAY 24
typedef unsigned int TimeList; /* has to be at least DAY bits */

/* set a time on a list */
#define Set(tlist, hour) tlist |= 1<<hour

/* check whether a time is set or not */
#define IsSet(tlist, hour) (tlist & 1<<hour)

/* return the intersection of two lists */
#define Intersection(tlist1, tlist2) (tlist1 & tlist2)

/* set number random times to the list tlist */
void RandomTimes(int *tlist, int number)
{
  int val;
  *tlist = 0;
  while (number) {
	  val = rand() % DAY;
	  if (!IsSet(*tlist, val)) {
		  Set(*tlist, val);
		  number--;
	  }
  }
} /* RandomTimes() */


int main(int argc, char **argv)
{
  int PID,	/* process-ID */
	  P;	/* number of processes */ 

  /* own variables */
  int i;

  /* keep these 3 calls */
  MPI_Init(&argc, &argv);
  MPI_Comm_rank(MPI_COMM_WORLD, &PID);
  MPI_Comm_size(MPI_COMM_WORLD, &P);

  /* actual code */

  srand(PID);
  RandomTimes(&ownlist, 16);

  /* print own list */
  printf("0 Proc %d: My times are :", PID );
  for (i = 0; i < DAY; i++)
	  if (IsSet(ownlist, i))
		  printf(" %02d", i); 
  printf("\n");


  /* your code here, include printing of result for each participant  */

  /* keep this call */
  MPI_Finalize();

  exit(0);

}