begin if(zt==1)begin {ls1,ls2}={ls1,ls2}; end else if({ls1,ls2}==8'h59){ls1,ls2}=0; else if(ls2==9)begin ls2=0;ls1=ls1+1;end else ls2=ls2+1;//60计数器 if(zt==1)begin {yb1,yb2}={yb1,yb2}; end else if({yb1,yb2}==8'h99){yb1,yb2}=0; else if(yb2==9)begin yb2=0;yb1=yb1+1;end else yb2=yb2+1;//100计数器 /*判断月是否为大小月且判断2月是否在闰年*/ if({month,month1}==1|{month,month1}==3|{month,month1}==5|{month,month1}==7|{month,month1}==8|{month,month1}==10|{month,month1}==8'h12) {daymax,daymax1}=8'h31; else if({month,month1}==4|{month,month1}==6|{month,month1}==9|{month,month1}==8'h11) begin {daymax,daymax1}=8'h30; end else if({month,month1}==2)begin if({year,year1,year2,year3}%400==0||({year,year1,year2,year3}%4==0&&{year,year1,year2,year3}%100!=0)){daymax,daymax1}=8'h28; else {daymax,daymax1}=8'h29; 请给这段代码加上注释 end

好的，以下是加上注释后的代码：

begin
    if (zt == 1) begin
        {ls1, ls2} = {ls1, ls2};  // 时钟不变
    end
    else if ({ls1, ls2} == 8'h59) begin
        {ls1, ls2} = 0;  // 时钟归零
    end
    else if (ls2 == 9) begin
        ls2 = 0;
        ls1 = ls1 + 1;  // 秒进位
    end
    else
        ls2 = ls2 + 1;  // 秒加 1

    if (zt == 1) begin
        {yb1, yb2} = {yb1, yb2};  // 计数器不变
    end
    else if ({yb1, yb2} == 8'h99) begin
        {yb1, yb2} = 0;  // 计数器归零
    end
    else if (yb2 == 9) begin
        yb2 = 0;
        yb1 = yb1 + 1;  // 计数器进位
    end
    else
        yb2 = yb2 + 1;  // 计数器加 1

    // 判断月的天数
    if ({month, month1} == 1 | {month, month1} == 3 | {month, month1} == 5 | {month, month1} == 7 | {month, month1} == 8 | {month, month1} == 10 | {month, month1} == 8'h12)
        {daymax, daymax1} = 8'h31;  // 大月，31 天
    else if ({month, month1} == 4 | {month, month1} == 6 | {month, month1} == 9 | {month, month1} == 8'h11)
        {daymax, daymax1} = 8'h30;  // 小月，30 天
    else if ({month, month1} == 2) begin
        if ({year, year1, year2, year3} % 400 == 0 || ({year, year1, year2, year3} % 4 == 0 && {year, year1, year2, year3} % 100 != 0)) 
            {daymax, daymax1} = 8'h28;  // 闰年，29 天
        else
            {daymax, daymax1} = 8'h29;  // 平年，28 天
    end
end