📌 Question

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.

🧑‍💻 Code Example

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)
            q <= data;
        else if (ena==2'b01) // rotates right
            q <= { q[0], q[99:1] };
        else if (ena==2'b10) // rotates left
            q <= { q[98:0], q[99] };
    end
    
endmodule

📚 Reference