Subversion Repositories raptor64

`include "Raptor64_opcodes.v"

`timescale 1ns / 1ps

//=============================================================================

//        __

//   \\__/ o\    (C) 2012,2013  Robert Finch

//    \  __ /    All rights reserved.

//     \/_//     robfinch<remove>@opencores.org

//       ||

//  

//      Raptor64_bitfield.v

//  - bitfield datapath operations

//

//  

// This source file 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.                                      

//                                                                          

// This source file 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 program.  If not, see <http://www.gnu.org/licenses/>.    

//                                                                          

//

//=============================================================================

//

//`define I_BFEXTS      1

//`define I_SEXT                1

module Raptor64_bitfield(xIR, a, b, o, masko);

parameter DWIDTH=64;

input [31:0] xIR;

input [DWIDTH-1:0] a;

input [DWIDTH-1:0] b;

output [DWIDTH-1:0] o;

reg [DWIDTH-1:0] o;

output [DWIDTH-1:0] masko;

reg [DWIDTH-1:0] o1;

reg [DWIDTH-1:0] o2;

wire [6:0] xOpcode = xIR[31:25];

wire [2:0] xFunc3 = xIR[2:0];

// generate mask

reg [DWIDTH-1:0] mask;

assign masko = mask;

wire [5:0] mb = xIR[8:3];

wire [5:0] me = xIR[14:9];

wire [5:0] ml = me-mb;           // mask length-1

integer nn,n;

always @(mb or me or nn)

        for (nn = 0; nn < DWIDTH; nn = nn + 1)

                mask[nn] <= (nn >= mb) ^ (nn <= me) ^ (me >= mb);

always @(xOpcode,xFunc3,mask,b,a,mb)

case (xOpcode)

`BITFIELD:

        case(xFunc3)

        `BFINS:         begin

                                        o2 = a << mb;

                                        for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? o2[n] : b[n];

                                end

        `BFSET:         begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? 1'b1 : a[n]; end

        `BFCLR:         begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? 1'b0 : a[n]; end

        `BFCHG:         begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? ~a[n] : a[n]; end

        `BFEXTU:        begin

                                        for (n = 0; n < DWIDTH; n = n + 1)

                                                o1[n] = mask[n] ? a[n] : 1'b0;

                                        o = o1 >> mb;

                                end

`ifdef I_BFEXTS

        `BFEXTS:        begin

                                        for (n = 0; n < DWIDTH; n = n + 1)

                                                o1[n] = mask[n] ? a[n] : 1'b0;

                                        o2 = o1 >> mb;

                                        for (n = 0; n < DWIDTH; n = n + 1)

                                                o[n] = n > ml ? o2[ml] : o2[n];

                                end

`endif

`ifdef I_SEXT

        `SEXT:          begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? a[mb] : a[n]; end

`endif

        default:        o = {DWIDTH{1'b0}};

        endcase

default:        o = {DWIDTH{1'b0}};

endcase

endmodule