cvvalidpix.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* unpublished proprietary information of Silicon Graphics, Inc., and *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: cvvalidpix.v,v 1.1.1.1 2002/05/17 06:07:45 blythe Exp $
/////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module: cvvalidpix
// description: generate one bit indicating if the current pixel
// is valid or not. Active high.
//
// designer: Mike M. Cai 6/16/94
//
/////////////////////////////////////////////////////////////////////////
module cvvalidpix( // output
valid_pixel,
// inputs
valid_pixel_m,
new_span, reset, gclk);
output valid_pixel;
input valid_pixel_m;
input new_span, reset, gclk;
reg s1, s0;
reg valid_pixel;
always @(posedge gclk or negedge reset)
if ( reset == 1'h0)
begin
s1 <= 1'h0;
s0 <= 1'h0;
end
else begin
s1 <= ~new_span & ( s1 | (~valid_pixel_m & s0));
s0 <= ~new_span & valid_pixel_m & ~s1;
valid_pixel <= s1 ? 1'h0 : valid_pixel_m;
end
endmodule // cvvalidpix