题解 | #移位运算与乘法#

移位运算，实现乘法与除法；

输入data_in，

若要实现2*data_in，则可以写成{data_in，1'b0};

若要实现4*data_in，则可以写成{data_in，2'b00};

若要实现3*data_in，则可以写成data_in + {data_in，1'b0};

`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_reg;

always@(posedge clk or negedge rst)begin
    if(!rst)begin
        cnt <= 2'd0;
    end
    else begin
        cnt <=  cnt + 1'b1;
    end
end
always@(posedge clk or negedge rst)begin
    if(!rst)begin
        out <= 11'd0;
        input_grant <= 1'b0;
    end
    else begin
        case(cnt)
        2'd0:begin
                out <= d;
                d_reg <= d;
                input_grant <= 1'b1;
            end
        2'd1:begin
                out <= d_reg + {d_reg,1'b0};
                input_grant <= 1'b0;
            end    
        2'd2:begin
                out <= d_reg + {d_reg,1'b0} + {d_reg,2'b00};
                input_grant <= 1'b0;
            end    
        2'd3:begin
                out <= {d_reg,3'b00};
                input_grant <= 1'b0;
            end 
        default:
            input_grant <= 1'b0;       
        endcase
    end
end
//*************code***********//
endmodule