// ========== Copyright Header Begin ==========================================
// OpenSPARC T2 Processor File: dmu_clu_crm_arb.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
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// ========== Copyright Header End ============================================
// synopsys sync_set_reset "rst_l"
// >>>>>>>>>>>>>>>>>>>>>>>>> Parameter Declarations <<<<<<<<<<<<<<<<<<<<<<<<<
// >>>>>>>>>>>>>>>>>>>>>>>>> Port Declarations <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// >>>>>>>>>>>>>>>>>>>>>>>>> Data Type Declarations <<<<<<<<<<<<<<<<<<<<<<<<<
// ~~~~~~~~~~~~~~~~~~~~~~~~~ REGISTERS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ********** Flops **********
reg [(N-1):0] pointer_reg;
// ~~~~~~~~~~~~~~~~~~~~~~~~~ NETS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
wire [(N-1):0] req_masked;
wire [(N-1):0] mask_higher_pri_reqs;
wire [(N-1):0] grant_masked;
wire [(N-1):0] unmask_higher_pri_reqs;
wire [(N-1):0] grant_unmasked;
// >>>>>>>>>>>>>>>>>>>>>>>>> 0-in Checkers <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
-req req[0] req[1] req[2]
-gnt (grant[0] & ~grnt_lck) (grant[1] & ~grnt_lck) (grant[2] & ~grnt_lck)
// >>>>>>>>>>>>>>>>>>>>>>>>> RTL Model <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
// --------------------------------------------------------
// Mask_Expand Round-Robin Arbiter
// --------------------------------------------------------
// Simple priority arbitration for masked portion
assign req_masked = req & pointer_reg;
assign mask_higher_pri_reqs[N-1:1] = (mask_higher_pri_reqs[N-2: 0] |
assign mask_higher_pri_reqs[0] = 1'b0;
assign grant_masked[N-1:0] = (req_masked[N-1:0] &
~mask_higher_pri_reqs[N-1:0]);
// Simple priority arbitration for unmasked portion
assign unmask_higher_pri_reqs[N-1:1] = (unmask_higher_pri_reqs[N-2:0] |
assign unmask_higher_pri_reqs[0] = 1'b0;
assign grant_unmasked[N-1:0] = req[N-1:0] & ~unmask_higher_pri_reqs[N-1:0];
// Use grant_masked if there is any there, otherwise use grant_unmasked
assign no_req_masked = ~(|req_masked);
assign grant = ({N{no_req_masked}} & grant_unmasked) | grant_masked;
// Generate arbiter pointer update
assign mask_ptr_sel = |req_masked & ~grnt_lck;
assign unmask_ptr_sel = |req & ~grnt_lck;
// Pointer update : only update if there's a req
pointer_reg <= {N{1'b1}};
else if (mask_ptr_sel) // select if masked arbiter used
pointer_reg <= mask_higher_pri_reqs;
else if (unmask_ptr_sel) // select if unmasked arbiter used
pointer_reg <= unmask_higher_pri_reqs;
endmodule // dmu_clu_crm_arb