#include "mat_mul.h"

#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;
  
  int j;
  int i;
  int k;
  int kk, kk_min;

  int bs = 32;
  int NM = (N/8)*8;
  float Aik;

  for (kk = 0; kk < K; kk += bs) {

      for (i = start; i < end; ++i) {
        kk_min = (kk+bs <= K) ? kk+bs : K;
        for (k = kk; k < kk_min; ++k) {
          Aik = A[i * K + k];
          for (j = 0; j < NM; j+=8) {
            C[i * N + j  ] += Aik * B[k * N + j  ];
            C[i * N + j+1] += Aik * B[k * N + j+1];
            C[i * N + j+2] += Aik * B[k * N + j+2];
            C[i * N + j+3] += Aik * B[k * N + j+3];
            C[i * N + j+4] += Aik * B[k * N + j+4];
            C[i * N + j+5] += Aik * B[k * N + j+5];
            C[i * N + j+6] += Aik * B[k * N + j+6];
            C[i * N + j+7] += Aik * B[k * N + j+7];
          }
          for (j; 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 * 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);
  }
}