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/* $Id: aeMB2_bsft.v,v 1.3 2008-04-28 08:15:25 sybreon Exp $

**

** AEMB2 EDK 6.2 COMPATIBLE CORE

** Copyright (C) 2004-2008 Shawn Tan <shawn.tan@aeste.net>

**

** This file is part of AEMB.

**

** AEMB is free software: you can redistribute it and/or modify it

** under the terms of the GNU Lesser General Public License as

** published by the Free Software Foundation, either version 3 of the

** License, or (at your option) any later version.

**

** AEMB 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 Lesser General

** Public License for more details.

**

** You should have received a copy of the GNU Lesser General Public

** License along with AEMB. If not, see <http:**www.gnu.org/licenses/>.

*/

/**

 * Two Cycle Barrel Shift Unit

 * @file aeMB2_bsft.v

 * This implements a 2 cycle barrel shifter. The design can be further

   optimised depending on architecture.

 */

// 420 LUTS

module aeMB2_bsft (/*AUTOARG*/

   // Outputs

   bsf_mx,

   // Inputs

   opa_of, opb_of, opc_of, imm_of, gclk, grst, dena, gpha

   );

   parameter AEMB_BSF = 1; ///< implement barrel shift  

   output [31:0] bsf_mx;

   input [31:0]  opa_of;

   input [31:0]  opb_of;

   input [5:0]    opc_of;

   input [10:9]  imm_of;

   // SYS signals

   input         gclk,

                 grst,

                 dena,

                 gpha;

   /*AUTOREG*/

   reg [31:0]     rBSLL, rBSRL, rBSRA;

   reg [31:0]     rBSR;

   reg [10:9]    imm_ex;

   wire [31:0]    wOPB = opb_of;

   wire [31:0]    wOPA = opa_of;

   // STAGE-1 SHIFTERS

   // logical

   always @(posedge gclk)

     if (grst) begin

        /*AUTORESET*/

        // Beginning of autoreset for uninitialized flops

        rBSLL <= 32'h0;

        rBSRL <= 32'h0;

        // End of automatics

     end else if (dena) begin

        rBSLL <= #1 wOPA << wOPB[4:0];

        rBSRL <= #1 wOPA >> wOPB[4:0];

     end

   // arithmetic

   always @(posedge gclk)

     if (grst) begin

        /*AUTORESET*/

        // Beginning of autoreset for uninitialized flops

        rBSRA <= 32'h0;

        // End of automatics

     end else if (dena)

       case (wOPB[4:0])

         5'd00: rBSRA <= wOPA;

         5'd01: rBSRA <= {{(1){wOPA[31]}}, wOPA[31:1]};

         5'd02: rBSRA <= {{(2){wOPA[31]}}, wOPA[31:2]};

         5'd03: rBSRA <= {{(3){wOPA[31]}}, wOPA[31:3]};

         5'd04: rBSRA <= {{(4){wOPA[31]}}, wOPA[31:4]};

         5'd05: rBSRA <= {{(5){wOPA[31]}}, wOPA[31:5]};

         5'd06: rBSRA <= {{(6){wOPA[31]}}, wOPA[31:6]};

         5'd07: rBSRA <= {{(7){wOPA[31]}}, wOPA[31:7]};

         5'd08: rBSRA <= {{(8){wOPA[31]}}, wOPA[31:8]};

         5'd09: rBSRA <= {{(9){wOPA[31]}}, wOPA[31:9]};

         5'd10: rBSRA <= {{(10){wOPA[31]}}, wOPA[31:10]};

         5'd11: rBSRA <= {{(11){wOPA[31]}}, wOPA[31:11]};

         5'd12: rBSRA <= {{(12){wOPA[31]}}, wOPA[31:12]};

         5'd13: rBSRA <= {{(13){wOPA[31]}}, wOPA[31:13]};

         5'd14: rBSRA <= {{(14){wOPA[31]}}, wOPA[31:14]};

         5'd15: rBSRA <= {{(15){wOPA[31]}}, wOPA[31:15]};

         5'd16: rBSRA <= {{(16){wOPA[31]}}, wOPA[31:16]};

         5'd17: rBSRA <= {{(17){wOPA[31]}}, wOPA[31:17]};

         5'd18: rBSRA <= {{(18){wOPA[31]}}, wOPA[31:18]};

         5'd19: rBSRA <= {{(19){wOPA[31]}}, wOPA[31:19]};

         5'd20: rBSRA <= {{(20){wOPA[31]}}, wOPA[31:20]};

         5'd21: rBSRA <= {{(21){wOPA[31]}}, wOPA[31:21]};

         5'd22: rBSRA <= {{(22){wOPA[31]}}, wOPA[31:22]};

         5'd23: rBSRA <= {{(23){wOPA[31]}}, wOPA[31:23]};

         5'd24: rBSRA <= {{(24){wOPA[31]}}, wOPA[31:24]};

         5'd25: rBSRA <= {{(25){wOPA[31]}}, wOPA[31:25]};

         5'd26: rBSRA <= {{(26){wOPA[31]}}, wOPA[31:26]};

         5'd27: rBSRA <= {{(27){wOPA[31]}}, wOPA[31:27]};

         5'd28: rBSRA <= {{(28){wOPA[31]}}, wOPA[31:28]};

         5'd29: rBSRA <= {{(29){wOPA[31]}}, wOPA[31:29]};

         5'd30: rBSRA <= {{(30){wOPA[31]}}, wOPA[31:30]};

         5'd31: rBSRA <= {{(31){wOPA[31]}}, wOPA[31]};

       endcase // case (wOPB[4:0])

   // STAGE-2 SHIFT

   always @(posedge gclk)

     if (grst) begin

        /*AUTORESET*/

        // Beginning of autoreset for uninitialized flops

        imm_ex <= 2'h0;

        rBSR <= 32'h0;

        // End of automatics

     end else if (dena) begin

        case (imm_ex)

          2'o0: rBSR <= #1 rBSRL;

          2'o1: rBSR <= #1 rBSRA;

          2'o2: rBSR <= #1 rBSLL;

          default: rBSR <= #1 32'hX;

        endcase // case (imm_ex)

        imm_ex <= #1 imm_of[10:9]; // delay 1 cycle     

     end

   assign        bsf_mx = (AEMB_BSF[0]) ? rBSR : 32'hX;

endmodule // aeMB2_bsft

/*

 $Log: not supported by cvs2svn $

 Revision 1.2  2008/04/26 01:09:05  sybreon

 Passes basic tests. Minor documentation changes to make it compatible with iverilog pre-processor.

 Revision 1.1  2008/04/18 00:21:52  sybreon

 Initial import.

*/