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// ========== Copyright Header Begin ==========================================
// 
// OpenSPARC T1 Processor File: tlu_rrobin_picker.v
// Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.
// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.
// 
// The above named program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public
// License version 2 as published by the Free Software Foundation.
// 
// The above named 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 work; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
// 
// ========== Copyright Header End ============================================
////////////////////////////////////////////////////////////////////////
/*
//      Description:    Round-Robin Picker for 4 eventss.
//			Differs from lsu'v rrobin picker by the
//			fact that there is no default 1-hot event.
*/
////////////////////////////////////////////////////////////////////////
// Global header file includes
////////////////////////////////////////////////////////////////////////
// system level definition file which contains the/*
/* ========== Copyright Header Begin ==========================================
* 
* OpenSPARC T1 Processor File: sys.h
* Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.
* 
* The above named program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License version 2 as published by the Free Software Foundation.
* 
* The above named 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 work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
* 
* ========== Copyright Header End ============================================
*/
// -*- verilog -*-
////////////////////////////////////////////////////////////////////////
/*
//
// Description:		Global header file that contain definitions that 
//                      are common/shared at the systme level
*/
////////////////////////////////////////////////////////////////////////
//
// Setting the time scale
// If the timescale changes, JP_TIMESCALE may also have to change.
`timescale	1ps/1ps
 
//
// JBUS clock
// =========
//
 
 
 
// Afara Link Defines
// ==================
 
// Reliable Link
 
 
 
 
// Afara Link Objects
 
 
// Afara Link Object Format - Reliable Link
 
 
 
 
 
 
 
 
 
 
// Afara Link Object Format - Congestion
 
 
 
 
 
 
 
 
 
 
 
// Afara Link Object Format - Acknowledge
 
 
 
 
 
 
 
 
 
 
 
// Afara Link Object Format - Request
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
// Afara Link Object Format - Message
 
 
 
// Acknowledge Types
 
 
 
 
// Request Types
 
 
 
 
 
// Afara Link Frame
 
 
 
//
// UCB Packet Type
// ===============
//
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
//
// UCB Data Packet Format
// ======================
//
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
// Size encoding for the UCB_SIZE_HI/LO field
// 000 - byte
// 001 - half-word
// 010 - word
// 011 - double-word
// 111 - quad-word
 
 
 
 
 
 
 
//
// UCB Interrupt Packet Format
// ===========================
//
 
 
 
 
 
 
 
 
 
 
//`define UCB_THR_HI             9      // (6) cpu/thread ID shared with
//`define UCB_THR_LO             4             data packet format
//`define UCB_PKT_HI             3      // (4) packet type shared with
//`define UCB_PKT_LO             0      //     data packet format
 
 
 
 
 
 
 
//
// FCRAM Bus Widths
// ================
//
 
 
 
 
 
 
//
// ENET clock periods
// ==================
//
 
 
 
 
//
// JBus Bridge defines
// =================
//
 
 
 
 
 
 
 
 
 
 
 
//
// PCI Device Address Configuration
// ================================
//
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                        // time scale definition
 
module tlu_rrobin_picker (/*AUTOARG*/
   // Outputs
   pick_one_hot, 
   // Inputs
   events, tlu_rst_l, clk
   );
 
input 	[3:0]	events ;		// multi-hot; events that could be chosen
// this siganl was modified to abide to the Niagara reset methodology
input		tlu_rst_l ;			// reset - active low
input		clk ;
 
output	[3:0]	pick_one_hot ;  // one-hot; events that must be chosen
//
// this signal was added to abide to the Niagara reset methodology
wire	tlu_rst ;	
 
// This section was modified to abide to the Niagara synthesis methodology
//
// reg	[3:0]	pick_status ;	
wire	pick_status_reset ;	
wire	[3:0]	pick_status_in ;	
wire	[3:0]	pick_status ;	
 
wire	events_unpicked ;
wire	[3:0]	pe_mask ;
 
//
// this signal was added to abide to the Niagara reset methodology
assign tlu_rst = ~tlu_rst_l;
 
assign	events_unpicked = |(events[3:0] & ~pick_status[3:0]) ;
			// term replicated.
 
// priority encode mask
assign	pe_mask[3:0] =
		events_unpicked ? 
		(events[3:0] & ~pick_status[3:0]) : 	// choose from eventss that have not picked.
		events[3:0] ;				// else all eventss on equal terms
 
assign	pick_one_hot[0] = 
		pe_mask[0] ;
		//pe_mask[0] | ~(|pe_mask[3:0]);		// none requesting then 0 is forced hot
assign	pick_one_hot[1] = 
		pe_mask[1] & ~pe_mask[0] ;
assign	pick_one_hot[2] = 
		pe_mask[2] & ~(|pe_mask[1:0]) ;
assign	pick_one_hot[3] = 
		pe_mask[3] & ~(|pe_mask[2:0]) ;
 
// This section was modified to abide to the Niagara synthesis methodology
//
// Define Pick Status
//always	@ (posedge clk)
//	begin
//		if ((&(pick_status[3:0] | pick_one_hot[3:0])) | tlu_rst) 
//			pick_status[3:0] <= 4'b0000 ;	// clear pick_status
//		else
//			pick_status[3:0] <= pick_status[3:0] | pick_one_hot[3:0] ;
//					// term replicated
//	end
 
assign pick_status_reset = (&(pick_status[3:0] | pick_one_hot[3:0])) | tlu_rst;
assign pick_status_in    = pick_status[3:0] | pick_one_hot[3:0]; 
 
dffr #(4)  dffre_pick_status  (
        .din (pick_status_in[3:0]), .q (pick_status[3:0]),
        .rst (pick_status_reset), .clk (clk),
        .se  (1'b0),  .si  (),       .so ()
        );
 
endmodule