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 [10:0] out1;
reg [10:0] out2;
reg [10:0] out3;
always @(posedge clk or negedge rst)
 if (rst == 1'b0)
   cnt <= 1'b0;
 else if (cnt == 2'b11)
   cnt <= 1'b0;
else 
   cnt <= cnt + 1'b1;
always @(posedge clk or negedge rst)
 if (rst == 1'b0)
   out <= 11'b0;
 else if(cnt == 1'b0)
   begin
    out <= d;
   out1 <= (d <<2) - d;
   out2 <= (d <<3) - d;
   out3 <= d << 3;
   end
 else if (cnt == 2'b01)
   out <=  out1;
 else if (cnt == 2'b10)
  out <= out2;
 else if (cnt == 2'b11)
  out <= out3;

always @(posedge clk or negedge rst)
 if (rst == 1'b0)
   input_grant <= 1'b0;
 else if(cnt == 1'b0)
   input_grant <= 1'b1;
 else
  input_grant <= 1'b0;
//*************code***********//
endmodule