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 [1:0] cnt;
reg [7:0] d_r;
always @(posedge clk or negedge rst) begin
    if(!rst) begin
        cnt <= 2'b0;
    end
    else begin
        cnt <= cnt + 2'd1;
    end
end
always @(posedge clk or negedge rst) begin
    if(!rst) begin
        out <= 0;
        input_grant <= 0;
        d_r <= 0;
    end
    else begin
        case (cnt) 
            2'd0 : begin
                out <= d;
                d_r <= d;
                input_grant <= 1'b1;
            end
            2'd1 : begin
                out <= {3'b0,d_r} + ({3'b0,d_r}<<1);
                input_grant <= 1'b0; 
            end
            2'd2 : begin
                out <= {3'b0,d_r} + ({3'b0,d_r}<<1) + ({3'b0,d_r}<<2);
            end
            2'd3 : begin
                out <= {3'b0,d_r}<<3;
            end
            default : begin
                out <= 0;
                input_grant <= 0;
            end
        endcase
    end
end
always @(posedge clk or negedge rst) begin
    if(!rst) begin

    end

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