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hone/gist:24697

Created Nov 14, 2008
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#include <mpi.h>
#include <iostream>
#include <string.h>
#include <gameoflife.hpp>
const int DIMENSIONS = 16;
const int DEAD = 0;
const int ALIVE = 1;
const int ITERATIONS = 64;
const int LENGTH = DIMENSIONS * DIMENSIONS;
int global_grid[ LENGTH ] = {
0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,
1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};
void print_grid( int iteration, int * grid )
{
std::cout << "Iteration " << iteration << ":\n";
for( int y = 0; y < DIMENSIONS; y++ )
{
for( int x = 0; x < DIMENSIONS; x++ )
{
std::cout << grid[offset( x, y )] << " ";
}
std::cout << std::endl;
}
}
int offset( int x, int y )
{
return x + ( y * DIMENSIONS );
}
int count_alive_neighbors( int x, int y, int * rows )
{
int count = 0;
for( int i = -1; i <= 1; i++ )
{
for( int j = -1; j <= 1; j++ )
{
int new_x = x + i;
int new_y = y + j;
int value;
// wrap around for x
if( new_x < 0 )
new_x = DIMENSIONS - 1;
if( new_x >= DIMENSIONS )
new_x = 0;
// don't count itself
if( i == 0 && j == 0 )
value = 0;
else
value = rows[offset( new_x, new_y )];
count += value;
}
}
return count;
}
bool check_neighborhood( int x, int y, int * rows )
{
int alive_count = count_alive_neighbors( x, y, rows );
if( rows[offset( x, y )] == DEAD )
{
if( alive_count == 3 )
return true;
}
else
{
if( alive_count == 2 || alive_count == 3 )
return true;
}
return false;
}
int * process_rows( int * rows, int amount_to_process )
{
int * new_rows = new int[amount_to_process * DIMENSIONS];
for( int i = 1; i <= amount_to_process; i++ )
{
for( int x = 0; x < DIMENSIONS; x++ )
{
if( check_neighborhood( x, i, rows ) )
new_rows[offset( x, i - 1 )] = ALIVE;
else
new_rows[offset( x, i - 1 )] = DEAD;
}
}
return new_rows;
}
int * setup_rows( int start_index, int end_index )
{
// send actual + 2 rows
int start_offset = 0;
int length = end_index - start_index + 3;
int * rows = new int[length * DIMENSIONS];
// copy last row (wrap around) and copy 1 less in cell size
if( start_index == 0 )
{
start_offset = DIMENSIONS;
length--;
for( int i = 0; i < DIMENSIONS; i++ )
rows[offset( i, 0 )] = global_grid[offset( i, (DIMENSIONS - 1) )];
}
// copy first row (wrap around) and copy 1 less in cell size
if( end_index == DIMENSIONS - 1 )
{
length--;
for( int i = 0; i < DIMENSIONS; i++ )
rows[offset( i, length - 1 )] = global_grid[offset( i, 0 )];
}
// copy rest of the rows
for( int j = 0; j < length; j++ )
for( int i = 0; i < DIMENSIONS; i++ )
rows[offset( i + start_offset, j )] = global_grid[offset( i, j )];
return rows;
}
int main( int argc, char ** argv )
{
const int NUM_SEND_ROWS = 5;
int num_procs = 0; // number of processes
int ID; // process (or node) id
MPI_Status stat; // MPI status parameter
MPI_Init( & argc, &argv ); // initialize MPI environment
MPI_Comm_rank( MPI_COMM_WORLD, &ID ); // find rank of this process in the group
MPI_Comm_size( MPI_COMM_WORLD, &num_procs ); // find number of processes in the group
if( ID == 0 )
{
print_grid( 0, global_grid );
for( int i = 1; i <= ITERATIONS; i++ )
{
// temp grid to pass in
int * rows = setup_rows( 0, DIMENSIONS - 1 );
int * new_rows = process_rows( rows, DIMENSIONS );
// copy back to global grid
memcpy( global_grid, new_rows, sizeof( global_grid ) );
print_grid( i, global_grid );
delete[] new_rows;
new_rows = NULL;
delete[] rows;
rows = NULL;
}
}
MPI_Finalize();
}
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