File content as of revision 5:4409ff66b434:

/*----------------------------------copyright---------------------------------*/
//      licensed for personal and academic use.
//      commercial use must be approved by the account-holder of
//      gated.clock@gmail.com
/*-----------------------------------module-----------------------------------*/
        module reg_16
        (
         oParallel,                             // parallel-output data.
         iParallel1,                            // parallel-input  data.
         iParallel0,                            // parallel-input  data.
         iSel,                                  // select the parallel input.
         oSerial,                               // serial-output data.
         iSerial,                               // serial-input data.
         iLoadEnable,                           // parallel-load-enable.
         iShiftEnable,                          // serial-shift-enable.
         iResetN,                               // synchronous reset*.
         iClk                                   // module clock.
        );
/*--------------------------------description-----------------------------------
        a 16-bit parallel shift-register with 2 selectable input buses.
-------------------------------------notes--------------------------------------
        shifting is LSB->MSB.
------------------------------------defines-----------------------------------*/
/*-----------------------------------ports------------------------------------*/
        output  [15:0]  oParallel;              // parallel-output data.
        input   [15:0]  iParallel1;             // parallel-input  data.
        input   [15:0]  iParallel0;             // parallel-input  data.
        input           iSel;                   // select the parallel input.
        output          oSerial;                // serial-output data.
        input           iSerial;                // serial-input data.
        input           iLoadEnable;            // parallel-load-enable.
        input           iShiftEnable;           // serial-shift-enable.
        input           iResetN;                // synchronous reset*.
        input           iClk;                   // module clock.
/*-----------------------------------wires------------------------------------*/
        wire    [15:0]  oParallel;              // parallel-output data.
        wire    [15:0]  iParallel1;             // parallel-input  data.
        wire    [15:0]  iParallel0;             // parallel-input  data.
        wire            iSel;                   // select the parallel input.
        wire    [15:0]  wParallelIn;            // select the parallel input.
        wire            oSerial;                // serial-output data.
        wire            iSerial;                // serial-input data.
        wire            iLoadEnable;            // parallel-load-enable.
        wire            iShiftEnable;           // serial-shift-enable.
        wire            iResetN;                // synchronous reset*.
        wire            iClk;                   // module clock.
/*---------------------------------registers----------------------------------*/
        reg     [15:0]  rRegister;              // the register.
/*---------------------------------variables----------------------------------*/
/*---------------------------------parameters---------------------------------*/
/*-----------------------------------clocks-----------------------------------*/
/*---------------------------------instances----------------------------------*/
        mux16x2 U0_mux16x2                      // data-input selection.
        (
         .iDin1(iParallel1),
         .iDin0(iParallel0),
         .iSel (iSel),
         .oDout(wParallelIn)
        );
/*-----------------------------------logic------------------------------------*/
        always @ (posedge iClk or negedge iResetN)
        begin
               if (!iResetN)     rRegister <= 16'h0000;
          else if (iLoadEnable)  rRegister <= wParallelIn;
          else if (iShiftEnable) rRegister <= {rRegister[14:0], iSerial};
          else                   rRegister <= rRegister;
        end

        assign oParallel = rRegister;           // propagate parallel-out.
        assign oSerial   = rRegister[15];       // propagate serial-out.
/*-------------------------------*/endmodule/*--------------------------------*/