Subversion Repositories theia_gpu

`timescale 1ns / 1ps

`include "aDefinitions.v"

/**********************************************************************************

Theia, Ray Cast Programable graphic Processing Unit.

Copyright (C) 2010  Diego Valverde (diego.valverde.g@gmail.com)

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; either version 2

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

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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

***********************************************************************************/

module Module_BusArbitrer

(

input wire Clock,

input wire Reset,

input wire [`MAX_CORES-1:0] iRequest,

output wire [`MAX_CORES-1:0] oGrant,

output wire [`MAX_CORE_BITS-1:0] oBusSelect

);

wire[`MAX_CORES-1:0] wCurrentMasterMask;

wire[`MAX_CORE_BITS-1:0] wCurrentBusMaster;

wire wCurrentRequest;

//Just one requester can have the bus at a given

//point in time, the mask makes sure this happens

genvar i;

generate

for (i = 0; i < `MAX_CORES; i = i +1)

begin : ARB

        assign oGrant[i] = iRequest[i] & wCurrentMasterMask[i];

end

endgenerate

//When a requester relinquishes the bus (by negating its [iRequest] signal),

//the switch is turned to the next position

//So while iRequest == 1 the ciruclar list will not move

CIRCULAR_SHIFTLEFT_POSEDGE_EX # (`MAX_CORES) SHL_A

(

 .Clock( Clock ),

 .Enable( ~wCurrentRequest ),

 .Reset( Reset ),

 .Initial(`MAX_CORES'b1),

 .O( wCurrentMasterMask )

);

assign oBusSelect = wCurrentBusMaster;

//Poll the current request

assign wCurrentRequest = iRequest[ wCurrentBusMaster ];

UPCOUNTER_POSEDGE # (`MAX_CORE_BITS ) UP1

(

        .Clock( Clock ),

        .Reset( Reset ),

        .Initial( `MAX_CORE_BITS'd0 ),

        .Enable(~wCurrentRequest),

        .Q(wCurrentBusMaster)

);

endmodule