13 Finite State Machines

Fsm1

 这里需要实现一个简单的摩尔状态机，即输出只与状态有关的状态机。

我这里代码看上去比长一点，答案用的case和三目运算符，结果是一样的。

module top_module(
    input clk,
    input areset,    // Asynchronous reset to state B
    input in,
    output out);//  

    parameter A=0, B=1; 
    reg state, next_state;

    always @(*) begin    // This is a combinational always block
        if(state ==A)begin
            if(in==1)
                next_state=A;
            else
                next_state=B;
        end
        else if(state ==B)begin
            if(in==1)
                next_state=B;
            else
                next_state=A;
        end        
    end

    always @(posedge clk, posedge areset) begin    // This is a sequential always block
        if(areset)
            state <= B;
        else 
            state <= next_state;
    end

    // Output logic
    assign out = (state == B);

endmodule