design/sys/iop/niu/rtl/niu_rdmc_rr_arbiter.v

// ========== Copyright Header Begin ==========================================
//
// OpenSPARC T2 Processor File: niu_rdmc_rr_arbiter.v
// Copyright (C) 1995-2007 Sun Microsystems, Inc. All Rights Reserved
// 4150 Network Circle, Santa Clara, California 95054, U.S.A.
//
// * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; version 2 of the License.
//
// This 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 program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// For the avoidance of doubt, and except that if any non-GPL license
// choice is available it will apply instead, Sun elects to use only
// the General Public License version 2 (GPLv2) at this time for any
// software where a choice of GPL license versions is made
// available with the language indicating that GPLv2 or any later version
// may be used, or where a choice of which version of the GPL is applied is
// otherwise unspecified.
//
// Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
// CA 95054 USA or visit www.sun.com if you need additional information or
// have any questions.
//
// ========== Copyright Header End ============================================
/*************************************************************************
 *
 * File Name    : niu_rdmc_rr_arbiter.v
 * Author Name  : Jeanne Cai
 * Description  :
 * Date Created : 10/29/2002
 *
 * Copyright (c) 2002, Sun Microsystems, Inc.
 * Sun Proprietary and Confidential
 *
 * Notes:
 *
 *************************************************************************/

module niu_rdmc_rr_arbiter (    req,
                                token,
                                gnt
                                );

input[3:0]      req;
input[3:0]      token;
output[3:0]     gnt;

reg[3:0] gnt;

always @ (req or token)
begin
        if (token[0])
        begin
                gnt[0] = req[0];
                gnt[1] = !req[0] & req[1];
                gnt[2] = !req[0] & !req[1] & req[2];
                gnt[3] = !req[0] & !req[1] & !req[2] & req[3];
        end
        else if (token[1])
        begin
                gnt[1] = req[1];
                gnt[2] = !req[1] & req[2];
                gnt[3] = !req[1] & !req[2] & req[3];
                gnt[0] = !req[1] & !req[2] & !req[3] & req[0];
        end
        else if (token[2])
        begin
                gnt[2] = req[2];
                gnt[3] = !req[2] & req[3];
                gnt[0] = !req[2] & !req[3] & req[0];
                gnt[1] = !req[2] & !req[3] & !req[0] & req[1];
        end
        else if (token[3])
        begin
                gnt[3] = req[3];
                gnt[0] = !req[3] & req[0];
                gnt[1] = !req[3] & !req[0] & req[1];
                gnt[2] = !req[3] & !req[0] & !req[1] & req[2];
        end
        else
        begin
                gnt[0] = req[0];
                gnt[1] = !req[0] & req[1];
                gnt[2] = !req[0] & !req[1] & req[2];
                gnt[3] = !req[0] & !req[1] & !req[2] & req[3];
        end
end

endmodule