module clock(CLK,CLK_1K,MODE,CHANGE,TURN,ALERT,HOU,MIN,SEC,LD_AL,LD_H,LD_M);
input CLK,CLK_1K,MODE,CHANGE,TURN;
output [7:0] HOU,MIN,SEC;
output ALERT,LD_AL,LD_H,LD_M;
reg [7:0] HOU,MIN,SEC,THOU,TMIN,TSEC,AHOU,AMIN;
reg [1:0] m,fm,sound;
reg LD_H,LD_M;
reg CLK_1Hz,CLK_2Hz,mclk,hclk;
reg alert1,alert2,ear;
reg count1,count2,lcount1,lcount2;
wire ct1,ct2,lct1,lct2,m_clk,h_clk;

always @(posedge CLK)
begin
   CLK_2Hz<=~CLK_2Hz;
   if(sound==3)
      begin sound<=0;ear<=1;end
            //ear信號用于產生或屏蔽聲音
   else 
      begin sound<=sound+1;ear<=0;end
end

always @(posedge CLK_2Hz)
   CLK_1Hz<=~CLK_1Hz; //產生1Hz的時基信號

always @(posedge MODE)   //MODE信號控制3鐘功能的轉換
   begin if(m==2) m<=0;  //m=0：計時功能
         else m<=m+1;    //m=1：鬧鐘功能
   end                   //m=2：手動校時

always @(TURN)
   fm<=~fm;     //校時時選擇調整分鐘還是小時

always
begin case(m)
      2:begin if(fm)
                 begin
                   count1<=CHANGE;
                   {LD_H,LD_M}<=2'b01;
                 end
              else
                 begin
                   count2<=CHANGE;
                   {LD_H,LD_M}<=2'b10;
                 end
              {count1,count2}<=0;

        end
      1:begin if(fm)
                 begin
                   lcount1<=CHANGE;
                   {LD_H,LD_M}<=2'b01;
                 end
              else
                 begin
                   lcount2<=CHANGE;
                   {LD_H,LD_M}<=2'b10;
                 end
              {lcount1,lcount2}<=0;

        end
      default:{count1,count2,lcount1,lcount2,LD_H,LD_M}<=0;
     endcase
end

always @(posedge CLK_1Hz)  //秒計時和秒調整
  if(!(TSEC^8'h59)|TURN&(!m))
    begin TSEC<=0;
          if(!(TURN&(!m)))
            mclk<=1;
    end
  else begin
     if(TSEC[3:0]==9)
           begin TSEC[3:0]<=0;
                 TSEC[7:4]<=TSEC[7:4]+1;
           end
     else TSEC[3:0]<=TSEC[3:0]+1;
       mclk<=0;
       end

assign m_clk=mclk|count1;
assign h_clk=hclk|count2;
assign ct1=CLK|m_clk;    //ct1用于計時、校時中的分鐘計數
assign ct2=CLK|h_clk;    //ct2用于計時、校時中的小時計數 
assign lct1=CLK|lcount1; //lct1用于定時狀態下調整分鐘信號
assign lct2=CLK|lcount2; //lct2用于定時狀態下調整小時信號

always @(posedge ct1)    //分計時和分調整
  begin if(TMIN==8'h59)
          begin TMIN<=0;
                hclk<=1;
          end
        else begin
          if(TMIN[3:0]==9)
             begin TMIN[3:0]<=0;
                   TMIN[7:4]<=TMIN[7:4]+1;
             end
         else TMIN[3:0]<=TMIN[3:0]+1;
            hclk<=0;
            end
  end

always @(posedge ct2)    //小時計時和小時調整
   if(THOU==8'h23)
        THOU<=0;
   else begin
          if(THOU[3:0]==9)
             begin THOU[3:0]<=0;
                 THOU[7:4]<=THOU[7:4]+1;
             end
          else THOU[3:0]<=THOU[3:0]+1;
        end

always @(posedge lct1)    //鬧鐘定時中分鐘調整
   if(AMIN==8'h59)
        AMIN<=0;
   else if(AMIN[3:0]==9)
             begin AMIN[3:0]<=0;
                 AMIN[7:4]<=AMIN[7:4]+1;
             end
          else AMIN[3:0]<=AMIN[3:0]+1;
        
always @(posedge lct2)    //鬧鐘定時中小時調整
   if(AHOU==8'h23)
        AHOU<=0;
   else begin
          if(AHOU[3:0]==9)
             begin AHOU[3:0]<=0;
                 AHOU[7:4]<=AHOU[7:4]+1;
             end
          else AHOU[3:0]<=AHOU[3:0]+1;
       end
always    //鬧鐘功能：產生鬧鈴信號
   if((THOU==AHOU)&&(TMIN==AMIN)&&(AHOU|AMIN)&&(!CHANGE))
     //若按住"CHANGE"鍵不放就可以屏蔽鬧鈴
      if(TSEC<8'h30)  alert1<=1; //設定鬧鈴聲的長短，這里設為30秒
      else alert1<=0;
   else alert1<=0;

always
  case(m)
  0:begin HOU<=THOU;  //計時狀態下時、分、秒顯示
          MIN<=TMIN;
          SEC<=TSEC;
    end
  1:begin HOU<=AHOU;  //定時狀態下時、分、秒顯示
          MIN<=AMIN;
          SEC<=8'hzz;
    end
  2:begin HOU<=THOU;  //校時狀態下時、分、秒顯示
          MIN<=TMIN;
          SEC<=8'hzz;
    end
 endcase

assign LD_AL=(AHOU|AMIN)?1:0;

always     //整點報時功能：產生整點報時信號
   begin if((TMIN==8'h59)&&(TSEC>8'h54)||(!(TMIN|TSEC)))
            if(TSEC>8'h54) 
               alert2<=ear & CLK_1K; //產生短音
            else
               alert2<=!ear & CLK_1K; //產生長音
        else alert2<=0;
   end
assign ALERT=((alert1)?CLK_1K & CLK:0)|alert2;
             //鬧鈴音和整點報時信號輸出
endmodule