题解 | #自动贩售机2#
自动贩售机2
https://www.nowcoder.com/practice/298dec1c3dce45c881f3e53e02558828
`timescale 1ns/1ns
module seller2(
input wire clk ,
input wire rst ,
input wire d1 ,
input wire d2 ,
input wire sel ,
output reg out1,
output reg out2,
output reg out3
);
//*************code***********//
parameter s0=8'b00000001,
s1=8'b00000010,
s2=8'b00000100,
s3=8'b00001000,
s4=8'b00010000,
s5=8'b00100000,
s6=8'b01000000;
reg [7:0]n_state;
reg [7:0]c_state;
wire [2:0]reg_d;
assign reg_d={sel,d1,d2};
always@(posedge clk or negedge rst)
if(!rst)
c_state<=s0;
else
c_state<=n_state;
always@(*)
case(c_state)
s0:begin
if(reg_d[1:0]==2'b10)
n_state=s1;
else if(reg_d[1:0]==2'b01)
n_state=s2;
end
s1:begin
if(reg_d[1:0]==2'b10)
n_state=s2;
else if(reg_d[1:0]==2'b01)
n_state=s3;
end
s2:begin
if(reg_d[1:0]==2'b10)
n_state=s3;
else if(reg_d[1:0]==2'b01)
n_state=s4;
end
s3:begin
if(reg_d[2]==0)
n_state=s0;
else if(reg_d[1:0]==2'b10)
n_state=s4;
else if(reg_d[1:0]==2'b01)
n_state=s5;
else
n_state=n_state;
end
s4:begin
if(reg_d[2]==0)
n_state=s0;
else if(reg_d[1:0]==2'b10)
n_state=s5;
else if(reg_d[1:0]==2'b01)
n_state=s6;
else
n_state=n_state;
end
s5:begin
n_state=s0;
end
s6:begin
n_state=s0;
end
default:n_state=s0;
endcase
always@(posedge clk or negedge rst)
if(!rst)begin
out1<=0;
out2<=0;
out3<=0;
end
else begin
case(n_state)
s3:begin
if(reg_d[2]==0)begin
out1<=1;
out2<=0;
out3<=0;
end
else begin
out1<=0;
out2<=0;
out3<=0;
end
end
s4:begin
if(reg_d[2]==0)begin
out1<=1;
out2<=0;
out3<=1;
end
else begin
out1<=0;
out2<=0;
out3<=0;
end
end
s5:begin
if(reg_d[2]==1)begin
out1<=0;
out2<=1;
out3<=0;
end
else begin
out1<=0;
out2<=0;
out3<=0;
end
end
s6:begin
if(reg_d[2]==1)begin
out1<=0;
out2<=1;
out3<=1;
end
else begin
out1<=0;
out2<=0;
out3<=0;
end
end
default:begin
out1<=0;
out2<=0;
out3<=0;
end
endcase
end
//*************code***********//
endmodule
