Subversion Repositories raptor64

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

//      (C) 2006-2011  Robert Finch

//      All rights reserved.

//      robfinch@opencores.org

//

//      rolx16.v

//              Rotate or shift left by multiples of sixteen bits.

//

//

//

// 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/>.    

//                                                                          

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

//

// rol 0,16,32 or 48 bits

module rolx16(op, a, b, o);

parameter DBW = 32;

localparam DMSB = DBW-1;

input op;

input [DMSB:0] a;

input [1:0] b;

output [DMSB:0] o;

reg [DMSB:0] o;

wire [47:0] opx = {48{op}};

always @(b or a or opx) begin

        case (b)

        2'd0:   o <= a;

        2'd1:   o <= {a[DMSB-16:0],a[DMSB:DMSB-15]&opx[15:0]};

        2'd2:   o <= {a[DMSB-(32%DBW):0],a[DMSB:DMSB-(31%DBW)]&opx[31:0]};

        2'd3:   o <= {a[DMSB-(48%DBW):0],a[DMSB:DMSB-(47%DBW)]&opx[47:0]};

        endcase

end

endmodule