题解 | 移位运算与乘法

`timescale 1ns/1ns
module multi_sel(
input [7:0]d ,
input clk,
input rst,
output reg input_grant,
output reg [10:0]out
);
//*************code***********//

reg [2:0] cnt;
reg [10:0] d_latch;

always @(posedge clk or negedge rst) begin
    if (!rst) begin
        d_latch <= 0;
        input_grant <= 1'b0;
        out <= 0;
    end
    else if (cnt == 0) begin
        d_latch <= d;
        out <= d;
        input_grant <= 1'b1;
    end
    else if (cnt == 1) begin
        out <= d_latch * 3;
        input_grant <= 1'b0;
    end
    else if (cnt == 2) begin
        out <= d_latch * 7;
        input_grant <= 1'b0;
    end
    else if (cnt == 3) begin
        out <= d_latch * 8;
        input_grant <= 1'b0;
    end
end

always @(posedge clk or negedge rst) begin
    if (!rst) begin
        cnt <= 0;
    end
    else if (cnt >= 3) begin
        cnt <= 0;
    end else begin
        cnt <= cnt + 1;
    end
end


//*************code***********//
endmodule

题目针对输入分别进行*1、*3、*7、*8的村换操作。

因此通过引入一个cnt，指示这四个操作数的循环。同时在*1时进行锁存。