Function lua_settop

ThirdParty/lua/lua/lapi.c:171–185

LUA_API void lua_settop (lua_State *L, int idx) {
  StkId func = L->ci->func;
  lua_lock(L);
  if (idx >= 0) {
    api_check(idx <= L->stack_last - (func + 1), "new top too large");
    while (L->top < (func + 1) + idx)
      setnilvalue(L->top++);
    L->top = (func + 1) + idx;
  }
  else {
    api_check(-(idx+1) <= (L->top - (func + 1)), "invalid new top");
    L->top += idx+1;  /* 'subtract' index (index is negative) */
  }
  lua_unlock(L);
}


/*