at_ctw3.v
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/**************************************************************************
* *
* Copyright (C) 1994, Silicon Graphics, Inc. *
* *
* These coded instructions, statements, and computer programs contain *
* unpublished proprietary information of Silicon Graphics, Inc., and *
* are protected by Federal copyright law. They may not be disclosed *
* to third parties or copied or duplicated in any form, in whole or *
* in part, without the prior written consent of Silicon Graphics, Inc. *
* *
*************************************************************************/
// $Id: at_ctw3.v,v 1.1 2002/03/28 00:26:12 berndt Exp $
////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module: at_ctw3
// description: Counter for attribute buffers.
//
// designer: Phil Gossett
// date: 9/6/94
//
////////////////////////////////////////////////////////////////////////
module at_ctw3 (clk, rst, enb, a, b, c);
input clk;
input rst;
input enb;
output a;
output b;
output c;
reg [1:0] z;
// counter
always @(posedge clk or posedge rst)
begin
if (rst == 1'b1)
z <= 2'b00; // 0
else
z <= enb ? {z[0],(z == 2'b00)} : z;
end
assign a = enb & (z == 2'b00);
assign b = enb & (z == 2'b01);
assign c = enb & (z == 2'b10);
endmodule // at_ctw3