Design Question - Barrel Shifter

A barrel shifter is a combinatorial shifter that can shift its input data by a specified number of bit positions in a single clock cycle. It is extremely fast, as it can, in theory, perform an n-bit shift operation in a single clock cycle.

On the other hand, a shift-register is a sequential circuit that can perform a one-bit shift per clock cycle. A shift-register requires n clock cycles to perform an n-bit shift operation.

The high speed of the barrel shifter comes at a cost of increased resource utilization, additional congestion and reduced clock speeds. A single clock cycle shift requires a large number of multiplexers. The number of inputs to these muxes grow as the number of input bits to be shifted increase.

The complete RTL code for this block can be found here.
The main element of the Barrel Shifter is the combinatorial multiplexer which lists out all possible shift combinations.

// Use the shift distance (shf_dst)
// to left shift the input data 
always_comb
begin
   case (shf_dst)
      // No shift
      2'b00  : sig_dat_out = dat_in;

      // 1-bit shift
      2'b01  : sig_dat_out = {dat_in[2:0], 1'b0};

      // 2-bit shift
      2'b10  : sig_dat_out = {dat_in[1:0], 2'b0};

      // 3-bit shift
      3'b11  : sig_dat_out = {dat_in[  0], 3'b0};

      // default
      default : sig_dat_out = dat_in;
   endcase
end

Additional Questions -

1. What modifications are needed if the module needs to do Rotation instead of Shifting?
2. Design a Barrel Shifter when has a Left Shift as well as Right Shift functionality based on an additional input signal.
3. In a Xilinx FPGA, how can you implement a barrel shifter using DSP48s?