[英]Can enum be made an output in systemverilog?
在verilog中,我可以做这样的事情:
module controller (
input rstb, clk, start,
output reg [1:0] state, next_state
);
parameter S_idle = 2'b00, S_1 = 2'b01, S_2 = 2'b11;
always @ (posedge clk, negedge rstb)
begin
if (!rstb) state <= S_idle;
else state <= next_state;
end
...
endmodule
但是在 systemverilog 中,这会产生一个错误,因为我声明了state, next_state
两次:
module controller (
input rstb, clk, start,
output logic [1:0] state, next_state
);
enum logic [1:0] {S_idle, S_1, S_2} state, next_state;
always_ff @ (posedge clk, negedge rstb)
begin
if (!rstb) state <= S_idle;
else state <= next_state;
end
...
endmodule
我想我可以将我的输出端口重命名为state_out, next_state_out
并将它们分配给state, next_state
。 有没有更简单的方法来使用枚举作为输出?
当使用用户定义的类型时,你应该使用typedef
并将它们放在一个包中,以便它们可以在使用它们的模块之间共享。 否则,您会遇到类型不兼容分配错误。
package stuff;
typedef enum logic [1:0] {S_idle, S_1, S_2} state_t;
endpackage
module controller import stuff::*; (
input logic rstb, clk, start,
output state_t state, next_state
);
always_ff @ (posedge clk, negedge rstb)
begin
if (!rstb) state <= S_idle;
else state <= next_state;
end
...
endmodule
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