#include "matrix.hpp"

#include <omp.h>

int **D {nullptr};

// wavefront computation

void wavefront_omp(unsigned num_threads) {

// set up the dependency matrix

D = new int *[MB];

for(int i=0; i<MB; ++i) D[i] = new int [NB];

for(int i=0; i<MB; ++i){

for(int j=0; j<NB; ++j){

D[i][j] = 0;

}

}

omp_set_num_threads(num_threads);

#pragma omp parallel

{

#pragma omp single

{

matrix[M-1][N-1] = 0;

for( int k=1; k <= 2*MB-1; k++) {

int i, j;

if(k <= MB){

i = k-1;

j = 0;

}

else{

//assume matrix is square

i = MB-1;

j = k-MB;

}

for(; (k <= MB && i>=0) || (k > MB && j <= NB-1) ; i--, j++){

if(i > 0 && j > 0){

#pragma omp task depend(in:D[i-1][j], D[i][j-1]) depend(out:D[i][j]) firstprivate(i, j)

block_computation(i, j);

}

//top left corner

else if(i == 0 && j == 0){

#pragma omp task depend(out:D[i][j]) firstprivate(i, j)

block_computation(i, j);

}

//top edge

else if(j+1 <= NB && i == 0 && j > 0){

#pragma omp task depend(in:D[i][j-1]) depend(out:D[i][j]) firstprivate(i, j)

block_computation(i, j);

}

//left edge

else if(i+1 <= MB && i > 0 && j == 0){

#pragma omp task depend(in:D[i-1][j]) depend(out:D[i][j]) firstprivate(i, j)

block_computation(i, j);

}

//bottom right corner

else if(i == MB-1 && j == NB-1){

#pragma omp task depend(in:D[i-1][j] ,D[i][j-1]) firstprivate(i, j)

block_computation(i, j);

}

else{

assert(false);

}

}

}

#pragma omp taskwait

}

}

for ( int i = 0; i < MB; ++i ) delete [] D[i];

delete [] D;

}

std::chrono::microseconds measure_time_omp(unsigned num_threads) {

auto beg = std::chrono::high_resolution_clock::now();

wavefront_omp(num_threads);

auto end = std::chrono::high_resolution_clock::now();

return std::chrono::duration_cast<std::chrono::microseconds>(end - beg);

}