at_ctrb.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* unpublished proprietary information of Silicon Graphics, Inc., and *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_ctrb.v,v 1.1 2002/03/28 00:26:12 berndt Exp $
////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module: at_ctrb
// description: Counter for attribute buffers. Busy version.
//
// designer: Phil Gossett
// date: 10/28/94
//
////////////////////////////////////////////////////////////////////////
module at_ctrb (clk, rst, enb, cnt, z);
input clk;
input rst;
input enb;
input [5:0] cnt;
output z;
reg [5:0] ctr;
reg z;
// counter
always @(posedge clk or posedge rst)
begin
if (rst == 1'b1)
ctr <= 0;
else
ctr <= enb ? cnt : ((ctr == 6'b000000) ? 6'b000000 :
(ctr - 1));
end
always @(posedge clk)
begin
z <= (ctr != 6'b000000);
end
endmodule // at_ctrb