Encore SIM EDITOR SOFTWARE Guida Utente Scaricare il pdf (Pagina 103)

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Modeling Your Design

Dealing With Unassigned Nets

Consider the following example:

module test(A);

input A;

wire A;

DUT DUT_1 (A);

// assign A = 1'bz;

initial

$lsi_dumpports(DUT_1,"dump.out");

endmodule

module DUT(A);

input A;

wire A;

child child_1(A);

endmodule

module child(A);

input A;

wire Z,A,B;

and (Z,A,B);

endmodule

In this case, the top level wire A is undriven at the top level. It is an

input which goes to an input in DUT_1, then to an input in CHILD_1

and finally to an input of an AND gate in CHILD_1. When

$lsi_dumpports evaluates the drivers on port A of test.DUT_1, it

finds no drivers on either side of port A of DUT_1, and therefore gives

a code of F, tristate (input and output unconnected).

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Encore SIM EDITOR SOFTWARE Guida Utente Pagina 103