/*
 * Bryan Ward
 * char_mandel_mpi.c - generate grayscale mandelbrot - mpi 
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <complex.h>
#include <mpi.h>

#define width 12800
#define height 10240
#define iter 255
#define xmin -2.0
#define xmax 2.0
#define ymin -2.0
#define ymax 2.0
//#define I 0+1i  //needed for cray cc

unsigned char checkPoint (double complex c) 
{
        double complex z = 0; 
        unsigned char j = 0; 
        while ((creal (z) * creal (z) + cimag (z) * cimag (z)) < 4
               && j < iter)
        {
                z = z * z + c; 
                j++;
        }
        return j;
}

int main(int argc, char **argv)
{

	FILE *fl;

	//MPI
	int mpistate,size,rank;
	MPI_Status mpistatus;

	//Non-MPI
	unsigned char* buff;
	unsigned char* final;
	int i,j,segment;
	unsigned char* part;
	double complex c;
	double xpix,ypix;
//	double complex unit = 0 + 1i;
	double start;

	//MPI Initialization
	MPI_Init(&argc,&argv);
	MPI_Comm_size(MPI_COMM_WORLD,&size);
	MPI_Comm_rank(MPI_COMM_WORLD,&rank);

	start = MPI_Wtime();
	ypix = (ymax - ymin) / height;
	xpix = (xmax - xmin) / width;
	segment = width*height/size;
	
	part = (unsigned char *)malloc(sizeof(unsigned char)*segment);
	
	fprintf(stderr,"Processor %d starting to iterate over %d points\n",rank,segment);

	for (i = segment*rank;i < segment*(rank+1);i++)
	{
		c = xmin + (i%width * xpix) + (ymin + (i/height *ypix))*I;
		part[i-segment*rank] = checkPoint(c);
	}
	printf("Processor %d done calculating in %f seconds\n",rank,MPI_Wtime()-start);
//	MPI_Barrier(MPI_COMM_WORLD);
	if(rank == 0)
	{
		if((fl = fopen("mpibrot.pgm","w")) == NULL)
			fprintf(stderr,"Cannot open mpibrot.pgm");
	        fprintf (fl, "P5\n");
	        fprintf (fl, "#Copyright (C) 2007 Bryan Ward\n");
	        fprintf (fl, "%d\t%d\n", width, height);
	        fprintf (fl, "255\n");

		fwrite((void*)part,sizeof(unsigned char),segment,fl);

		buff = (unsigned char *)malloc(segment*sizeof(unsigned char));

		for(i = 1;i<size;i++)
		{
			if((mpistate=MPI_Recv(buff,segment,MPI_UNSIGNED_CHAR,i,MPI_ANY_TAG,MPI_COMM_WORLD,&mpistatus)) != MPI_SUCCESS)
			{
				fprintf(stderr,"MPI-Receive failed for rank %d\n",i);
			}
			else
			{
				fprintf(stderr,"MPI-Receive Success from rank %d\n",mpistatus.MPI_SOURCE);
			}

			fwrite((void*)buff,sizeof(unsigned char),segment,fl);
		}
	}
	else
	{
		if((mpistate= MPI_Send(part,segment,MPI_UNSIGNED_CHAR,0,rank,MPI_COMM_WORLD)) != MPI_SUCCESS)
		{
			fprintf(stderr,"MPI-Send failed for rank %d\n",rank);
		}
		else
		{
			fprintf(stderr,"MPI-Send Success for rank %d\n",rank);
		}
	}
	printf("Total time: %f seconds\n",MPI_Wtime()-start);
	MPI_Finalize();
	return 0;
}