private void I_ALR(string cmd)
{
skip_space();
int r1 = R();
skip_space();
if (cur_token != ',')
error("指令不完整,期望逗号(,)");
get_src_token();
skip_space();
int r2 = R();
skip_space();
if (cur_token != ',')
error("指令不完整,期望逗号(,)");
get_src_token();
skip_space();
int r3 = R();
format_line.AppendFormat ("R{0}, R{1}, R{2}", r1, r2, r3);
}