#include "mat_mul.h"
#include <cstdlib>
#include <cstdio>
#include <pthread.h>
#include <algorithm>
#define bsize 64

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
/*  for (int i = 0; i < M; ++i) {
      for (int j = 0; j < N; ++j) {
        for (int k = 0; k < K; ++k) {
          C[i * N + j] += A[i * K + k] * B[k * N + j];
        }
    }
  }
*/

  int pid = *(int*)data;
  int block = M / num_threads;
  int start = pid*block;
  int end = (pid == num_threads-1)? M: (pid+1)*block;
  float Mat_A;
  
  for (int kk=0; kk<K; kk+=bsize){
    for(int i=start; i<end; ++i){
      for(int k =kk; k<std::min(kk+bsize, K); ++k){
        Mat_A = A[i*K + k];
	      for(int j= 0; j<N; ++j){
          C[i*N+j] += Mat_A * 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 thread;
  //pthread_create(&thread, NULL, mat_mul_thread, NULL);
  //pthread_join(thread, NULL);
  
  /*
  pthread_t p_thread[num_threads];
  int thread_id[num_threads];
  int result[num_threads];
  //int status;

  for (int i=0; i<num_threads; i++){
    thread_id[i] = pthread_create(&p_thread[i], NULL, mat_mul_thread, NULL);

    if(thread_id[i]<0){
      perror("thread create error : ");
      exit(0);
    }
    else{
      printf("thread %d : created\n", i);
    }
  }

  for(int j=0; j<num_threads; j++){
    pthread_join(p_thread[j], (void **)&result[j]);
    printf("thread join : %d\n", j);
  }
  */
  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);
  }

}