sale2.v

sale

module sale(
  reset,   //low active
  charge, //button for get the charge
  clock,
  ten_in,
  five_in,
  one_in,
  p_five_in,
  goods_a,  // 1   dollar
  goods_b,  // 1.5 dollars
  goods_c,  // 2   dollars
  goods_d,  // 2.5 dollars
  goods_e,  // 3   dollars
  goods_out,
  one_back,
  p_five_back,
  total_money,
  flag_enough
  );
  
  
  input reset;
  
  input clock;
  
  input charge;
  
  input ten_in,
  five_in,
  one_in,
  p_five_in;
  
  input goods_a,  
  goods_b,  
  goods_c,  
  goods_d, 
  goods_e;    // buttons to press, which stands for a certain price;
  
  output[4:0]goods_out; //bit0: goods_a
  //bit1: goods_b
  //bit2: goods_c
  //bit3: goods_d
  //bit4: goods_e                      
  output[11:0] one_back,      
  p_five_back;    //charges
  
  output[11:0]total_money;
  //bit0 to bit3 stand for the part less than one dollar
  //bit4 to bit7 stand for ones of dollars
  //bit9 to bit11 stand for tens of dollars
  output flag_enough;  //whether the money input is enough for the goods to buy
  
  
  
  //***********************************/
  reg[4:0] goods_out;
  reg[3:0] one_back,p_five_back;
  reg[11:0] total_money;
  reg flag_enough;
  reg cout;
  reg money;
  reg[3:0] state;
  
  parameter IDLE=      4'b0001,
            GIVE_MONEY=4'b0010,
            BUY=       4'b0100,
            CHARGE=    4'b1000;
  
  
  
  always@(posedge clock)
  if(!reset)
  begin
    goods_out<=5'b0000;
    {one_back,p_five_back}<=0;
    total_money<=0;
    flag_enough<=0; 
    state<=IDLE;       
  end  
  else
  
  case(state)   
    IDLE:begin
      goods_out<=5'b00000;
      {one_back,p_five_back}<=0;
      total_money<=0;
      flag_enough<=0; 
      state<=GIVE_MONEY;       
    end   
    
    GIVE_MONEY:
    if(ten_in)         begin
      total_money<=total_money+100;
      state<=GIVE_MONEY;
    end
    else if(five_in)   begin
      total_money<=total_money+50;
      state<=GIVE_MONEY;
    end
    else if(one_in)    begin
      total_money<=total_money+10;
      state<=GIVE_MONEY;
    end
    else if(p_five_in) begin
      total_money<=total_money+5;
      state<=GIVE_MONEY;
    end
    else               state<=BUY;
    
    BUY:
    if(goods_a) 
    begin
      if(total_money>=10)
      begin
        total_money<=total_money-10;
        goods_out<=5'b00001;
        state<=BUY;
      end
      else
      begin 
        flag_enough<=0;
        state<=BUY;
      end
    end
    else if(goods_b)
    begin
      if(total_money>=15)
      begin
        total_money<=total_money-15;
        goods_out<=5'b00010;
        state<=BUY;
      end
      else 
      begin
        flag_enough<=0;
        state<=BUY;
      end
    end
    else if(goods_c)
    begin
      if(total_money>=20)
      begin
        total_money<=total_money-20;
        goods_out<=5'b00100;
      end
      else
      begin 
        flag_enough<=0;
        state<=BUY;
      end
    end
    else if(goods_d)
    begin
      if(total_money>=25)
      begin
        total_money<=total_money-25;
        goods_out<=5'b01000;
        state<=BUY;
      end
      else 
      begin
        flag_enough<=0;
        state<=BUY;
      end
    end  
    else if(goods_e)
    begin
      if(total_money>=30)
      begin
        total_money<=total_money-30;
        goods_out<=5'b10000;
        state<=BUY;
      end
      else
      begin
        flag_enough<=0;
        state<=BUY;
      end
    end
    else  state<=CHARGE;
    
    CHARGE:
    if(total_money>=10)
    begin
      one_back<=one_back+1;
      state<=CHARGE;
    end
    else if(total_money>=5) 
    begin   
      p_five_back<=p_five_back+1;
      state<=CHARGE;
    end
    else state<=IDLE;
    
  endcase
endmodule