#include "mat_mul.h"

#include <cstdlib>
#include <cstdio>
#include <pthread.h>
#include <algorithm>
//#define min(x, y) (x) < (y) ? (x) : (y)

static float *A, *B, *C;
static int M, N, K;
static int num_threads;
static int BLOCKSIZE = 64;

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;
  int bs = BLOCKSIZE;
  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];
	  int j = 0;
          for (; j < N; ++j) {
            C[i * N + j] += Aik * B[k * N + j];
          }
        }
      }
    
  }

//  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;

  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);
  }
  // TODO: create '_num_threads' pthreads
//  pthread_t thread;
//  pthread_create(&thread, NULL, mat_mul_thread, NULL);
//  pthread_join(thread, NULL);
}