iverilog/ivtest/ivltests/nblkpush.v

60 lines
1.7 KiB
Verilog

//
// Copyright (c) 2001 Stephan Boettcher <stephan@nevis.cloumbia.edu>
//
// This source code is free software; you can redistribute it
// and/or modify it in source code form 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
//
// Validates Non-blocking assignment propagation
// $Id: nblkpush.v,v 1.2 2005/07/07 16:25:20 stevewilliams Exp $
// Update: This test has a race in it that makes it not valid. The
// assumption that a blocking assign will push through the continuous
// assignment before the thread doing the assign is allowed to advance
// is not valid. This test only passes Verilog XL. Every other tool,
// commercial or otherwise, seems to FAIL this test. Therefore, this
// test should not be relied on.
module test;
reg a, b, c, d;
wire ab = a & b;
wire abc = ab | c;
wire abcd = abc & d;
initial
begin
a = 0;
b = 1;
c = 0;
d = 1;
#1;
a = 1;
if (abcd === 1)
begin
$display("PASSED");
$finish;
end
$display("FAILED ab=%b, abc=%b, abcd=%b", ab, abc, abcd);
#1;
if (abcd === 1)
$display("abcd value changed late");
else
$display("abcd value still wrong");
end
endmodule