std::vector<char> data;
int where = 0;

int img_read(void *user, char *dat, int size) {
  //printf("r%d\n", size);
  int amount = size;
  memcpy(dat, data.data() + where, amount);
  where += amount;
  return amount;
}


void img_skip (void *user, int n) {
  printf("s%d\n", n);
  where += n;
}

int img_eof (void *user) {
  printf("e\n");
  return 0;
}

int main() {
  auto start = std::chrono::system_clock::now();
  int w = 0, h = 0;
  auto f = std::ifstream("big.jpg", std::ios::binary|std::ios::ate);
  data.resize(f.tellg());
  f.seekg(0);
  f.read(data.data(), data.size());
  printf("%ld\n", data.size());

  //uint8_t *data = stbi_load("big.jpg", &w, &h, 0, 3);
  stbi_io_callbacks cb = {
    img_read, img_skip, img_eof
  };

  uint8_t *res = stbi_load_from_callbacks(&cb, nullptr, &w, &h, nullptr, 3);
  printf("%p\n", res);
  auto end = std::chrono::system_clock::now();
  printf("%f\n", std::chrono::duration<double>(end-start).count());
}