$system returns & fully random seeds - EDA Playground
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module Top;
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  function void set_true_random_seed(string file, int line);
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    integer fd, cnt, seed;
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    std::process p;
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    p = process::self();
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    $system( "head -4 /dev/urandom | od -N 4 -D -A n | awk '{print $1}' > seed.txt" );
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    fd = $fopen( "seed.txt", "r" );
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    cnt = $fscanf( fd, "%d", seed );
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    $fclose( fd );
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    $display( "%0t %s:%0d ",$time, file, line, "Set seed=%0d", seed );
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    p.srandom(seed);
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  endfunction
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  initial begin
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    $display( "$system=%0d", $system( "perl -e 'print q{Pass };exit 0;'" ) );
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    $display( "$system=%0d", $system( "perl -e 'print q{Fail };exit 1;'" ) );
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    set_true_random_seed(`__FILE__,`__LINE__);
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  end
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endmodule
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Illustrates how to use $system and provides a function that will produce a fully random seed. Note: It is important to print the seed value so that you can later reproduce a simulation if it happens to fail. The file and line inputs are in case you call this multiple times from multiple places. Note that it is not very fast, so you don't want to call it except to establish initial seeding at time zero.

Illustrates how to use $system and provides a function that will produce a fully random seed. Note: It is important to print the seed value so that you can later reproduce a simulation if it happens to fail. The file and line inputs are in case you call this multiple times from multiple places. Note that it is not very fast, so you don't want to call it except to establish initial seeding at time zero.

1770:0