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Specman E
Interview Questions

MAILBOX

A mailbox is a communication mechanism that allows messages to be exchanged between processes. Data can be sent to a mailbox by one process and retrieved by another.

Mailbox is a built-in class that provides the following methods:
--Create a mailbox: new()
--Place a message in a mailbox: put()
--Try to place a message in a mailbox without blocking: try_put()
--Retrieve a message from a mailbox: get() or peek()
--Try to retrieve a message from a mailbox without blocking: try_get() or try_peek()
--Retrieve the number of messages in the mailbox: num()

EXAMPLE:
program meain ;
mailbox my_mailbox;
initial begin
my_mailbox = new();
if (my_mailbox)
begin
fork
put_packets();
get_packets();
#10000;
join_any
end

#(1000);
$display("END of Program");
end

task put_packets();
integer i;
begin
for (i=0; i<10; i++)
begin
#(10);
my_mailbox.put(i);
$display("Done putting packet %d @time %d",i, $time);

end
end
endtask

task get_packets();
integer i,packet;
begin
for (int i=0; i<10; i++)
begin
my_mailbox.get(packet);
$display("Got packet %d @time %d", packet, $time);
end
end
endtask
endprogram

RESULTS:

Done putting packet 0 @time 10
Got packet 0 @time 10
Done putting packet 1 @time 20
Got packet 1 @time 20
Done putting packet 2 @time 30
Got packet 2 @time 30
Done putting packet 3 @time 40
Got packet 3 @time 40
Done putting packet 4 @time 50
Got packet 4 @time 50
Done putting packet 5 @time 60
Got packet 5 @time 60
Done putting packet 6 @time 70
Got packet 6 @time 70
Done putting packet 7 @time 80
Got packet 7 @time 80
Done putting packet 8 @time 90
Got packet 8 @time 90
Done putting packet 9 @time 100
Got packet 9 @time 100
END of Program

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