HDLBits Left/right rotator（Rotate100）

HDLBits Left/right rotator（Rotate100）

Build a 100-bit left/right rotator, with synchronous load and left/right enable. A rotator shifts-in the shifted-out bit from the other end of the register, unlike a shifter that discards the shifted-out bit and shifts in a zero. If enabled, a rotator rotates the bits around and does not modify/discard them.

• load: Loads shift register with data[99:0] instead of rotating.
• ena[1:0]: Chooses whether and which direction to rotate.
  • 2'b01 rotates right by one bit
  • 2'b10 rotates left by one bit
  • 2'b00 and 2'b11 do not rotate.
• q: The contents of the rotator.

 

module top_module(
    input clk,
    input load,
    input [1:0] ena,
    input [99:0] data,
    output reg [99:0] q); 
    
    always@(posedge clk) begin
        if (load) begin
            q<=data;
    end
        else begin
        case(ena)
            2'b00 : q<=q;
            2'b11 : q<=q;
            2'b01 : q={q[0],q[99:1]};
            2'b10 : q={q[98:0],q[99]};
        endcase
    end
    end   
endmodule