#include "mat_mul.h"

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

//#define MIN(x,y) ((x) < (y)) ? (x) : (y)
#define TS 32 
//#define TS 64

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

static int MIN(int a, int b) {
    return (a > b) ? b : a;
}

static void* mat_mul_thread(void *data) {
  // TODO: parallelize & optimize matrix multiplication
  int i,j,k;
  int /*ii,jj,*/kk;
  int ts = TS;
  int thread_id = * (int *) data;
  int slice     = M / num_threads;
  int start_ptr = slice * thread_id;
  int end_ptr   = (thread_id == (num_threads-1)) ? M : (thread_id+1) * slice;

  float A_mac;

  for (kk = 0; kk < K; kk += ts)
  {
    for (i = start_ptr; i < end_ptr; ++i)
    {
      for (k = kk; k < MIN(kk + ts, K); ++k)
      {
        A_mac = A[i * K + k];

        for (j = 0; j < N; ++j)
	{
          C[i * N + j] += A_mac * 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
  int i; 

  pthread_t *threads;
  threads = (pthread_t *) malloc(sizeof(pthread_t) * num_threads);

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

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