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 [1:0] oBusSelect

);

wire wFFMS_connect;

wire wIncRR_pointer;

wire[3:0] wCurrentMasterMask;

reg[3:0] wCurrentBusMaster;

wire wCurrentRequest;

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

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

assign oGrant[0] = iRequest[0] & wCurrentMasterMask[0];

assign oGrant[1] = iRequest[1] & wCurrentMasterMask[1];

assign oGrant[2] = iRequest[2] & wCurrentMasterMask[2];

assign oGrant[3] = iRequest[3] & wCurrentMasterMask[3];

//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 # (4) SHL_A

(

 .Clock( Clock ),

 .Enable( ~wCurrentRequest ),

 .Reset( Reset ),

 .Initial(4'b1),

 .O( wCurrentMasterMask )

);

assign oBusSelect = wCurrentBusMaster;

MUXFULLPARALELL_2SEL_GENERIC # ( 1 ) MUXA

 (

 .Sel(wCurrentBusMaster[1:0]),

  .I1(iRequest[0]),

  .I2(iRequest[1]),

  .I3(iRequest[2]),

  .I4(iRequest[3]),

  .O1( wCurrentRequest )

  );

always @ ( * )

begin

        case (wCurrentMasterMask)

                4'b0001: wCurrentBusMaster <= 0;

                4'b0010: wCurrentBusMaster <= 1;

                4'b0100: wCurrentBusMaster <= 2;

                4'b1000: wCurrentBusMaster <= 3;

                default: wCurrentBusMaster <= 0;

        endcase

end

endmodule