static void copy2buff (StkId top, int n, char *buff) {
  size_t tl = 0;  /* size already copied */
  do {
    size_t l = vslen(s2v(top - n));  /* length of string being copied */
    memcpy(buff + tl, svalue(s2v(top - n)), l * sizeof(char));
    tl += l;
  } while (--n > 0);
}