/* compile: /usr/local/mpich-1.2.0/bin/mpicc par.ex5_24.skel.c
   run : nice /usr/local/mpich-1.2.0/bin/mpirun -np 10 a.out

   Difference to ex23: block sends.

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

   All statements after MPI_Init are executed by (-np) 10 processes,
   PIDs are 0..P-1.

*/
   
#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
*/

/* 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)

/* Send the COUNT int:s starting from address ADDR to to destination
   process DEST */
#define BSend(DEST, ADDR, COUNT) MPI_Send(ADDR, COUNT, 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)

/* Receive a COUNT int:s to address starting ADDR from destination
   process SOURCE */
#define BReceive(SOURCE, ADDR, COUNT) MPI_Recv(ADDR, COUNT, MPI_INT, SOURCE, 0, MPI_COMM_WORLD, &tmpstat)


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

  /* own variables */
  int i, ok = 1;
  int *s_arr, *r_arr;

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

  /* actual code */

  /* space allocation */
  r_arr = (int*)malloc(P * sizeof(int));
  s_arr = (int*)malloc(P * sizeof(int));
  if (!r_arr || !s_arr)
	  exit(1);

  
  if (PID == 0) {
	  /* 1st processor sends block to all */
	  for (i = 0; i < P; i++)
		  s_arr[i] = i;

	  for (i = 1; i < P; i++)
		  BSend(i, s_arr, P);

  } else {

	  /* others receive from 1st */
	  BReceive(0, r_arr, P);

	  for (i = 0; i < P; i++) {
		  if (r_arr[i] != i) {
			  printf("Pros: %d, i: %d r_arr_i %d \n", PID, i, r_arr[i]);
			  ok = 0;
		  }
	  }

	  printf("Pros: %d ok = %d\n", PID, ok);
  }

  free(s_arr);
  free(r_arr);

  /* keep this call */
  MPI_Finalize();

  exit(0);

}