#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
#define MIN(a, b) (((a) < (b)) ? (a) : (b))

  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;

#if 0 
  int bs = 1024;
  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 < min(kk + bs, K); ++k) {
          Aik = A[i * K + k];
          int j;
          int size = min(jj + bs, N);
          int ssize = (size / 8) * 8;	  
	  for (j = jj; j < ssize; j += 8) {
            C[i * N + j + 0] += Aik * B[k * N + j + 0];
            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 < size; j++) {
            C[i * N + j] += Aik * B[k * N + j];
	  }
        }
      }
    }
  }
#else
  int bs = 32;
  for (int kk = 0; kk < K; kk += bs) {
    for (int i = start; i < end; ++i) {
      for (int k = kk; k < 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];
        }
      }
    }
  }
#endif

  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
#if 0 
  pthread_t thread;
  pthread_create(&thread, NULL, mat_mul_thread, NULL);
  pthread_join(thread, NULL);
#else
  printf("mat_mul - threads=%d, M=%d, K=%d, N=%d\n", _num_threads, M, K, N);
  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);
  }
#endif
}