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.
Program:
module top_module(
input clk,
input load,
input [1:0] ena,
input [99:0] data,
output reg [99:0] q);
always@(posedge clk )begin // don't need "negedge ena" in the list because i //synchronous
if(load)
q<=data[99:0];
else begin
case(ena) //choose mode to run
2'b00:; //2'b00 and 2'b11 do not rotate.
2'b01:q<={q[0],q[99:1]}; //2'b01 rotates right by one bit
2'b10:q<={q[98:0],q[99]}; //2'b10 rotates left by one bit
2'b11:; //2'b00 and 2'b11 do not rotate.
endcase
end
end
endmodule