//
void swap(void)
{
	MIN_ARGUMENTS(2);
	_stack->copy_obj_to_local(0, 0);
	_stack->copy_obj_to_local(1, 1);
	_stack->pop_back();
	_stack->pop_back();
	_stack->push_obj_from_local(0);
	_stack->push_obj_from_local(1);
}

void drop(void)
{
	MIN_ARGUMENTS(1);
	_stack->pop_back();
}

void drop2(void)
{
	MIN_ARGUMENTS(2);
	_stack->pop_back();
	_stack->pop_back();
}

void erase(void)
{
	while(_stack->size()>0)
		_stack->pop_back();
}

void dup(void)
{
	MIN_ARGUMENTS(1);
	_stack->copy_obj_to_local(0, 0);
	_stack->push_obj_from_local(0);
}

void dup2(void)
{
	MIN_ARGUMENTS(2);
	_stack->copy_obj_to_local(0, 0);
	_stack->copy_obj_to_local(1, 1);
	_stack->push_obj_from_local(1);
	_stack->push_obj_from_local(0);
}

void pick(void)
{
	MIN_ARGUMENTS(1);
	unsigned int to_pick = (unsigned int)getf();

	// treat stack depth errors
	if ((to_pick == 0) || (to_pick > _stack->size()))
	{
		ERR_CONTEXT(ret_missing_operand);
		return;
	}
	_stack->copy_obj_to_local(to_pick - 1, 0);
	_stack->push_obj_from_local(0);
}

void rot(void)
{
	MIN_ARGUMENTS(3);
	_stack->copy_obj_to_local(0, 0);
	_stack->copy_obj_to_local(1, 1);
	_stack->copy_obj_to_local(2, 2);
	_stack->pop_back();
	_stack->pop_back();
	_stack->pop_back();
	_stack->push_obj_from_local(1);
	_stack->push_obj_from_local(0);
	_stack->push_obj_from_local(2);
}

void depth(void)
{
    number num;
    num.set((floating_t)_stack->size());
    _stack->push_back(&num, num.size(), cmd_number);
}