#include "mat_mul.h"
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <pthread.h>

static float *A, *B, *C;
static int M, N, K;
static int num_threads;

static void* mat_mul_thread(void *data) {
  // TODO: parallelize & optimize matrix multiplication
  //
  
  int pid = * (int *) data;
  
  int slice = M / num_threads;
  int start = pid * slice;
  int end = (pid == num_threads-1)? M: (pid+1)*slice;

  float Aik;
  

for (int kk=0; kk< K; kk+=32){
	  for(int i=start; i<end; i++){
		  for(int k = kk; k < ((kk+32)<K ? (kk+32):K); ++k){
			  Aik = A[i*K+k];
	                  for( int j=0; j < N; ++j){
				  C[i*N+j]+=Aik*B[k*N+j];
			  }
		  }
	  }
  }
  return NULL;
}

void mat_mul(float *_A, float *_B, float *_C, int _M, int _N, int _K, int _num_threads) {
  A = _A, B = _B, C = _C;
  M = _M, N = _N, K = _K;
  num_threads = _num_threads;

  // TODO: create '_num_threads' pthreads
  pthread_t * threads;
  threads = (pthread_t *) malloc(sizeof(pthread_t) * num_threads);

  for (int i = 0; i < num_threads; i++) {
  
	  int * pid = (int *) malloc(sizeof(int));
	  *pid = i;
	  pthread_create(&threads[i], NULL, mat_mul_thread, pid);
  }

  for (int i = 0; i < num_threads; i++){
          pthread_join(threads[i], NULL);
  }
}