#include "mat_mul.h"

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

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

#define MIN(X, Y) (((X) < (Y)) ? (X) : (Y))

#ifdef __AVX512F__
#define IBS 64
#define KBS 40
#else
#define IBS 32
#define KBS 32
#endif

static void* mat_mul_thread(void *data) {
  const int m = M / num_threads;
  const int tid = *((int *) data);
  const int begin = (tid * m);
  const int end = (tid == num_threads - 1) ? M : (tid + 1) * m;
	float Aik;

  for (int ii = begin; ii < end; ii += IBS) {
    for (int kk = 0; kk < K; kk += KBS) {
      for (int i = ii; i < MIN(ii + IBS, end); ++i) {
        for (int k = kk; k < MIN(kk + KBS, K); ++k) {
          Aik = A[i * K + k];
          for (int j = 0; 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;

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

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

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