Verilog的停车系统

Question

我是verilog编码的新手，我试图为停车系统编写verilog代码。以下是我的代码。每当sense_entry变高时，我想分配一个停放槽。在Altera板中，当sense_entry变为1时，所有的槽都被分配。我才知道它是逻辑综合错误。怎么解决这个？ 示例：当sense_entry第一次变为1时，应分配slota。应该分配第二次插槽。

`module ParkingSystem(clock,reset,sense_entry,sense_exit_A,sense_exit_B,sense_exit_C,sense_exit_D,
slota,slotb,slotc,slotd);
  input sense_entry,sense_exit_A,sense_exit_B,sense_exit_C,sense_exit_D,clock,reset;
  output slota,slotb,slotc,slotd;
  reg slota,slotb,slotc,slotd;
  initial
  begin
    slota=1'b1;
    slotb=1'b1;
    slotc=1'b1;
    slotd=1'b1;
  end
  always@(reset or sense_entry or sense_exit_A or sense_exit_B or sense_exit_C or sense_exit_D)
  begin
  if(reset==1'b1)
    begin
      slota=1'b1;
      slotb=1'b1;
      slotc=1'b1;
      slotd=1'b1;
      $display("Reset Pressed");
      $display("slot A is alloted");
      $display("slot B is alloted");
      $display("slot C is alloted");
      $display("slot D is alloted");
    end
  else if(sense_entry==1'b1)
      begin
        if(slota==1'b1)
          begin
            slota=1'b0;
            $display("slot A is alloted");
          end
        else if(slotb==1'b1)
          begin
          slotb=1'b0; 
          $display("slot B is alloted");
          end
        else if(slotc==1'b1)
          begin 
            slotc=1'b0;
           $display("slot C is alloted"); 
          end
        else if(slotd==1'b1)
          begin 
            slotd=1'b0;
            $display("slot D is alloted");
          end
        else
          $display("slots are full");
      end
    else if(sense_exit_A==1'b1)
      begin
      if(slota==1'b0)
        begin
           slota=1'b1;
           $display("slot A is dealloted");
        end
        else 
        $display("No Car in slot A");
      end
    else if(sense_exit_B==1'b1)
      begin
      if(slotb==1'b0)
        begin
           slotb=1'b1;
           $display("slot B is dealloted");
        end
        else 
        $display("No Car in slot B");
      end
      else if(sense_exit_C==1'b1)
      begin
      if(slotc==1'b0)
        begin
           slotc=1'b1;
           $display("slot C is dealloted");
        end
        else 
        $display("No Car in slot C");
      end
      else if(sense_exit_D==1'b1)
      begin
      if(slotd==1'b0)
        begin
           slotd=1'b1;
           $display("slot D is dealloted");
        end
        else 
        $display("No Car in slot D");
      end
  end
  endmodule

`