barrelshifter.bsv

import Multiplexer::*;

interface BarrelShifterRight;
  method ActionValue#(Bit#(64)) rightShift(Bit#(64) val, Bit#(6) shiftAmt, Bit#(1) shiftValue);
endinterface

module mkBarrelShifterRight(BarrelShifterRight);
  function Bit #(w) barrel_shift_right(Int #(k) n, Bit #(w) arg, Bit#(1) shiftValue);
    Bit #(w) ans = 0;
    for(Integer j = 0; j < (valueOf(w) - n); j = j + 1)
      ans[j + n] = arg[j];
    for(Integer i = 0; i < n ; i = i + 1)
      ans[i] = shiftValue;
    return ans;
  endfunction
  
  method ActionValue#(Bit#(64)) rightShift(Bit#(64) val, Bit#(6) shiftAmt, Bit#(1) shiftValue);
    /* TODO: Implement right barrel shifter using six multiplexer */
    let shiftedVal = val;
    for(Integer i = 0; i < 6; i = i + 1)
      Int#(32) shiftNum = fromInteger(2 ** i);
      shiftedVal = barrel_shift_right(shiftNum, val, shiftValue);
      val = multiplexer_n(shiftAmt[i], shiftedVal, val);
    let result <- val;
    return result;
  endmethod
endmodule

interface BarrelShifterRightLogical;
  method ActionValue#(Bit#(64)) rightShift(Bit#(64) val, Bit#(6) shiftAmt);
endinterface

module mkBarrelShifterRightLogical(BarrelShifterRightLogical);
  let bsr <- mkBarrelShifterRight;
  method ActionValue#(Bit#(64)) rightShift(Bit#(64) val, Bit#(6) shiftAmt);
    /* TODO: Implement logical right shifter using the right shifter */
    let ans = bsr.rightShift(val, shiftAmt, 0);
    let result <- ans;
    return result;
  endmethod
endmodule

typedef BarrelShifterRightLogical BarrelShifterRightArithmetic;

module mkBarrelShifterRightArithmetic(BarrelShifterRightArithmetic);
  let bsr <- mkBarrelShifterRight;
  method ActionValue#(Bit#(64)) rightShift(Bit#(64) val, Bit#(6) shiftAmt);
    /* TODO: Implement arithmetic right shifter using the right shifter */
    let result <- ?;
    return 0;
  endmethod
endmodule