#include "mpi.h"
#include <stdio.h>
/* stdlib is needed for declaring malloc */
#include <stdlib.h>

#define MAX2(a, b) (((a)>(b)) ? (a) : (b))

int  GlobalReadInteger();
void Hello();
void Ring();
/*
void Stress();
void Globals();
*/

int main(int argc, char *argv[])
{
	
    int me, option, namelen, size;
    char processor_name[MPI_MAX_PROCESSOR_NAME];
	
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD,&me);
    MPI_Comm_size(MPI_COMM_WORLD,&size);
	
    if (size < 2) 
	{
		fprintf(stderr, "systest requires at least 2 processes");
		MPI_Abort(MPI_COMM_WORLD, 1);
    }
	
    MPI_Get_processor_name(processor_name,&namelen);
	
    fprintf(stderr,"Process %d is alive on %s\n", me, processor_name);
	fflush(stderr);

    while (1) 
	{
		
		MPI_Barrier(MPI_COMM_WORLD);
		
again:
		if (me == 0) 
		{
			/* Read user input for action */
			/* (void) printf("\nOptions: 0 = quit, 1 = Hello, 2 = Ring, 3 = Stress, ");
			(void) printf("4 = Globals : "); */
			(void) printf("\nOptions: 0 = quit, 1 = Hello, 2 = Ring :  ");
			(void) fflush(stdout);
		}
		option = GlobalReadInteger();
		if ((option < 0) || (option > 4))
			goto again;
		
		switch (option) 
		{
		case 0:
			MPI_Finalize();
			return (0);
		case 1:
			Hello();     break;
		case 2:
			Ring();      break;
			/*
			case 3:
			Stress();    break;
			case 4:
			Globals();   break;
			*/
		default:
			fprintf(stderr,"systest: invalid option %d\n", option);
			fflush(stderr);
			break;
		}
    }
}

int GlobalReadInteger()
/*
Process zero reads an integer from stdin and broadcasts
to everyone else
*/
{
    int me, value,  type = 999 , zero = 0;
	
    MPI_Comm_rank(MPI_COMM_WORLD, &me);
    if (me == 0) 
	{
		if (scanf("%d", &value) != 1)
		{
			fprintf(stderr,"failed reading integer value from stdin\n");
			fflush(stderr);
		}
    }
    MPI_Bcast(&value, 1, MPI_INT, 0, MPI_COMM_WORLD);
    return value;
}

void Hello()
/*
Everyone exchanges a hello message with everyone else.
The hello message just comprises the sending and target nodes.
*/
{
    int nproc, me;
    int type = 1;
    int buffer[2], node;
    MPI_Status status;
	
    MPI_Comm_rank(MPI_COMM_WORLD, &me);
    MPI_Comm_size(MPI_COMM_WORLD, &nproc);
	
    if (me == 0) 
	{
		printf("\nHello test ... show network integrity\n----------\n\n");
		fflush(stdout);
    }
	
    for (node = 0; node<nproc; node++) 
	{
		if (node != me) 
		{
			buffer[0] = me;
			buffer[1] = node;
			MPI_Send(buffer, 2, MPI_INT, node, type, MPI_COMM_WORLD);
			MPI_Recv(buffer, 2, MPI_INT, node, type, MPI_COMM_WORLD, &status);
			
			if ((buffer[0] != node) || (buffer[1] != me)) 
			{
				(void) fprintf(stderr, "Hello: %d!=%d or %d!=%d\n",
					buffer[0], node, buffer[1], me);
				fflush(stderr);
				printf("Mismatch on hello process ids; node = %d\n", node);
			}
			
			printf("Hello from %d to %d\n", me, node);
			fflush(stdout);
		}
    }
}

void Ring()       /* Time passing a message round a ring */
{
    int nproc, me;
    MPI_Status status;
    int type = 4;
    int left, right;
    char *buffer;
    int lenbuf, max_len;
    double us_rate;
    double start_ustime, used_ustime;
	
    MPI_Comm_rank(MPI_COMM_WORLD, &me);
    MPI_Comm_size(MPI_COMM_WORLD, &nproc);
    left = (me + nproc - 1) % nproc;
    right = (me + 1) % nproc;
	
    /* Find out how big a message to use */
	
    if (me == 0) 
	{
		(void) printf("\nRing test...time network performance\n---------\n\n");
		(void) printf("Input maximum message size: ");
		(void) fflush(stdout);
    }
    max_len = GlobalReadInteger();
    if ((max_len <= 0) || (max_len >= 4*1024*1024))
		max_len = 512*1024;
    if ((buffer = (char *) malloc((unsigned) max_len)) == (char *) NULL) 
	{
		printf("process %d could not allocate buffer of size %d\n", me, max_len);
		fflush(stdout);
		MPI_Abort(MPI_COMM_WORLD, 7777);
    }
	
    lenbuf = 1;
    while (lenbuf <= max_len) 
	{
		start_ustime = MPI_Wtime();
		if (me == 0) 
		{
			MPI_Send(buffer, lenbuf, MPI_CHAR, left, type, MPI_COMM_WORLD);
			MPI_Recv(buffer, lenbuf, MPI_CHAR, right, type, MPI_COMM_WORLD,&status);
		}
		else 
		{
			MPI_Recv(buffer, lenbuf, MPI_CHAR, right, type, MPI_COMM_WORLD,&status);
			MPI_Send(buffer, lenbuf, MPI_CHAR, left, type, MPI_COMM_WORLD);
		}
		used_ustime = MPI_Wtime() - start_ustime;
		
		if (used_ustime > 0)	/* rate is megabytes per second */
			us_rate = (double)(nproc*lenbuf / (used_ustime*(double)1000000));
		else
			us_rate = 0.0;
		if (me == 0) 
		{
			printf("len=%d bytes, used= %f sec., rate=%f Mbytes/sec\n",
				lenbuf, used_ustime, us_rate);
			fflush(stdout);
		}
		lenbuf *= 2;
    }
    if (me == 0)
	{
		printf("clock resolution in seconds: %10.8f\n", MPI_Wtick());
		fflush(stdout);
	}
    free(buffer);
}