FSD - Laborator 3

/*
 ============================================================================
 Name        : lab3.c
 Author      :
 Version     :
 Copyright   : Your copyright notice
 Description : Hello MPI World in C
 ============================================================================
 */

#include <stdio.h>
#include <string.h>
#include <math.h>
#include "mpi.h"

#define PROBE 1
#define REPLY 2
#define LEADER 3

#define SIZE_MSG 4

int main(int argc, char* argv[]) {
    int my_rank; /* rank of process */
    int p; /* number of processes */
    int source; /* rank of sender */
    int dest; /* rank of receiver */
    int tag = 0; /* tag for messages */
    MPI_Status status; /* return status for receive */

    /* start up MPI */
    MPI_Init(&argc, &argv);
    /* find out process rank */
    MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
    /* find out number of processes */
    MPI_Comm_size(MPI_COMM_WORLD, &p);

    int sendbuf[SIZE_MSG];
    int recvbuf[SIZE_MSG];
    int phase = 0;
    int leader = 0;

    int nodes[7] = {73, 28 ,74, 49, 66, 69, 71};
    int left = 0;
    int right = 0;

    if((my_rank - 1) < 0) {
        left = p - 1;
    } else {
        left = my_rank - 1;
    }
    right = (my_rank + 1) % p;

    sendbuf[0] = PROBE;
    sendbuf[1] = nodes[my_rank];
    sendbuf[2] = phase;
    sendbuf[3] = 1;
    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
    int flag = 1;
    while (flag) {
        MPI_Recv(recvbuf, SIZE_MSG, MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
        source = status.MPI_SOURCE;
        if(source == left) {
            switch (recvbuf[0]) {
            case PROBE:
                if(recvbuf[1] == nodes[my_rank]) {
                    sendbuf[0] = LEADER;
                    sendbuf[1] = nodes[my_rank];
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                }

                if(recvbuf[1] > nodes[my_rank] && recvbuf[3] < pow(2, recvbuf[3])) {
                    sendbuf[0] = PROBE;
                    sendbuf[1] = recvbuf[1];
                    sendbuf[2] = phase;
                    sendbuf[3] = recvbuf[3] + 1;
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                }

                if(recvbuf[1] > nodes[my_rank] && recvbuf[3] >= pow(2, recvbuf[3])) {
                    sendbuf[0] = REPLY;
                    sendbuf[1] = recvbuf[1];
                    sendbuf[2] = phase;
                    sendbuf[3] = recvbuf[3] + 1;
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                }
                break;
            case REPLY:
                if(recvbuf[1] != nodes[my_rank]) {
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                } else {
                    sendbuf[0] = PROBE;
                    sendbuf[1] = nodes[my_rank];
                    sendbuf[2] = phase + 1;
                    sendbuf[4] = 1;
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                }
                break;
            }
        } else {
            switch (recvbuf[0]) {
            case PROBE:
                if(recvbuf[1] == nodes[my_rank]) {
                    sendbuf[0] = LEADER;
                    sendbuf[1] = nodes[my_rank];
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                }

                if(recvbuf[1] > nodes[my_rank] && recvbuf[3] < pow(2, recvbuf[3])) {
                    sendbuf[0] = PROBE;
                    sendbuf[1] = recvbuf[1];
                    sendbuf[2] = phase;
                    sendbuf[3] = recvbuf[3] + 1;
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                }

                if(recvbuf[1] > nodes[my_rank] && recvbuf[3] >= pow(2, recvbuf[3])) {
                    sendbuf[0] = REPLY;
                    sendbuf[1] = recvbuf[1];
                    sendbuf[2] = phase;
                    sendbuf[3] = recvbuf[3] + 1;
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                }
                break;
            case REPLY:
                if(recvbuf[1] != nodes[my_rank]) {
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                } else {
                    sendbuf[0] = PROBE;
                    sendbuf[1] = nodes[my_rank];
                    sendbuf[2] = phase + 1;
                    sendbuf[4] = 1;
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                    MPI_Send(recvbuf, SIZE_MSG, MPI_INT, right, tag, MPI_COMM_WORLD);
                }
                break;
            case LEADER:
                leader = nodes[my_rank];
                if(recvbuf[1] != nodes[my_rank]) {
                    sendbuf[0] = LEADER;
                    sendbuf[1] = leader;
                    MPI_Send(sendbuf, SIZE_MSG, MPI_INT, left, tag, MPI_COMM_WORLD);
                    printf("I am leader %d with value %d\n", my_rank, leader);
                    flag = 0;
                }
                break;
            }
        }
    }
    /* shut down MPI */
    MPI_Finalize();

    return 0;
}