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// ========== Copyright Header Begin ==========================================

// 

// OpenSPARC T1 Processor File: sparc_ifu_lfsr5.v

// Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.

// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.

// 

// The above named program is free software; you can redistribute it and/or

// modify it under the terms of the GNU General Public

// License version 2 as published by the Free Software Foundation.

// 

// The above named program is distributed in the hope that it will be 

// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

// General Public License for more details.

// 

// You should have received a copy of the GNU General Public

// License along with this work; if not, write to the Free Software

// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

// 

// ========== Copyright Header End ============================================

////////////////////////////////////////////////////////////////////////

/*

//  Module Name: sparc_ifu_lfsr5

//  Description:

//  The IFQ is the icache input queue.  This communicates between the

//  IFU and the outside world.  It handles icache misses and

//  invalidate requests from the crossbar.

*/

////////////////////////////////////////////////////////////////////////

module sparc_ifu_lfsr5 (/*AUTOARG*/

   // Outputs

   out,

   // Inputs

   advance, clk, se, si, so, reset

   );

   input        advance;

   input        clk, se, si, so, reset;

   output [1:0] out;

   reg [4:0]    q_next;

   wire [4:0]   q;

/*

   always @ (posedge clk)

     begin

        out = $random;

     end // always @ posedge

 */

//   always @ (posedge clk)

//     begin

//      q[4:0] <= q_next[4:0];

//     end

   always @ (/*AUTOSENSE*/advance or q or reset)

     begin

              if (reset)

                q_next = 5'b11111;

              else if (advance)

                begin

                   // lfsr -- stable at 000000, period of 63

                   q_next[1] = q[0];

                   q_next[2] = q[1];

                   q_next[3] = q[2];

                   q_next[4] = q[3];

                   q_next[0] = q[1] ^ q[4];

                end

              else

                q_next = q;

     end // always @ (...

   assign out = {q[0], q[2]};

   dff_s #(5) lfsr_reg(.din  (q_next),

                     .q    (q),

                     .clk  (clk), .se(se), .si(), .so());

endmodule // sparc_ifu_lfsr5