#include "mat_mul.h"

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

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

static void* mat_mul_thread(void *data) {
  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;
  int bs = 48;
  for (int kk = 0; kk < K; kk += bs) {
   // for (int jj = 0; jj < N; jj += bs) {
      for (int i = start; i < end; ++i) {
        for (int k = kk; k < std::min(kk + bs, 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;
}

/*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];
        }
    }
  }	
  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;
  thread = (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(&thread[i], NULL, mat_mul_thread, pid);
  }
  for (int i = 0; i < num_threads ; i++) {
          pthread_join(thread[i], 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);

}
*/