#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;

#define min(a, b) (((a) < (b)) ? (a) : (b))
#define BLOCKSIZE 45

static void* mat_mul_thread(void *data) {
  int pid = * (int *) data;

  int slice = M / num_threads;      // 4096/20 : 204
  u_int64_t start = pid * slice;
  //eatch thread does 204 entiries Matrix Mul start: pid*204.
  u_int64_t end = pid == num_threads - 1 ? M : (pid + 1) * slice;
  float Aik;
  int bs = BLOCKSIZE;
  for (u_int64_t kk = 0; kk < (u_int64_t)K; kk += bs) {    //4ea
      u_int64_t mk = min(kk + bs, (u_int64_t)K);
      for (u_int64_t i = start; i < end; ++i) {
          for (u_int64_t k = kk; k < mk; ++k) {
              Aik = A[i * K + k];
              u_int64_t mmj = (N>>3)<<3;
              u_int64_t j = 0;
              for ( ; j < mmj; 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<(u_int64_t)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 * 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);
  }
}