#include <stdlib.h>
#include <stdio.h>
#include "pvm3.h"
#include "constants.h"

float work();

int main(void){
  int mytid, tids[MAX_CHILD], n, me, i, nproc, master;
  float data[DATA_SIZE], result;
  /* enroll in pvm */
  mytid = pvm_mytid();
  /* Receive data from master */
  pvm_recv(-1, MASTER_SLAVE);
  pvm_upkint(&nproc, 1, 1);
  pvm_upkint(tids, nproc, 1);
  pvm_upkint(&n, 1, 1);
  pvm_upkfloat(data, n, 1);
  /* Determine which slave I am (0 -- nproc-1) */
  for( i=0; i<nproc ; i++ )
    if( mytid == tids[i] ){ me = i; break; }
  printf("I'm slave with rank %d\n", me);
  /* Do calculations with data */
  result = work( me, n, data, tids, nproc );
  /* Send result to master */
  pvm_initsend(PvmDataDefault );
  pvm_pkint(&me, 1, 1 );
  pvm_pkfloat(&result, 1, 1 );
  master = pvm_parent();
  pvm_send(master, SLAVE_MASTER);
  /* Program finished. Exit PVM before stopping */
  pvm_exit();
  exit(EXIT_SUCCESS);
}

float work(int me, int n, float *data, int *tids, int nproc){
     /* Simple example: slaves exchange data with left neighbor (wrapping) */
  int i, dest;
  float psum = 0.0;
  float sum = 0.0;
  for(i = 0; i < n; i++){
    sum += me * data[i];
  }
  /* illustrate node-to-node communication */
  pvm_initsend(PvmDataDefault );
  pvm_pkfloat(&sum, 1, 1 );
  dest = me + 1;
  if( dest == nproc ) dest = 0;
  pvm_send(tids[dest], SLAVE_SLAVE);
  pvm_recv(-1, SLAVE_SLAVE);
  pvm_upkfloat(&psum, 1, 1);
  return(sum + psum);
}