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2-3

Modeling Your Design

end

initial begin

#10 if (a) $display("may not print");

end

endmodule

The solution is to delay the $display statement with a #0 delay:

initial begin

#10 if (a)

#0 $display("may not print");

end

You can also move it to the next time step with a non-zero delay.

Setting a Value Twice at the Same Time

In this example, the race condition occurs at time 10 because no

ordering is guaranteed between the two parallel initial blocks.

module race;

reg r1;

initial #10 r1 = 0;

initial #10 r1 = 1;

initial

#20 if (r1) $display("may not print");

endmodule

The solution is to stagger the assignments to register r1 by finite

time, so that the ordering of the assignments is guaranteed. Note that

using the nonblocking assignment (<=) in both assignments to r1

would not remove the race condition in this example.

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Encore SIM EDITOR SOFTWARE Guia do Utilizador Página 71