void s0(UCHARP beg, UCHARP buf, UCHARP end, ENVP env) {
  env->ret = (jmp_buf *)malloc(sizeof(int)*100); // allocate dumy fields. for protect real ret addres.
  env->ret = (jmp_buf *)malloc(sizeof(jmp_buf));
  if (env == NULL) {
    fprintf(stderr, "can't allocate jmp_buf");
    exit(0);
  }
  int ret;
  if ((ret = setjmp(env->ret)) == 0) {
    goto _s0(beg, buf, end, env);
  }
  //free(env->ret); danger!
  return;
}