Wednesday, 23 November 2016

Kill process in SystemVerilog using "disable fork" and "disable LABEL"

Most of us, have faced these some issues at least one time in our SystemVerilog programming while using "disable fork" and "disable LABEL".

Let's first go through below example,
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As shown in above example, "Process:1" is running continuously. Two different processes, "Process:2" and "Process:3" should run in parallel and any of two processes is completed, other process shall stop its execution due to join_any statement.

While simulating above code, you may face that when the disable fork is executed, "Process:1" also stop it's execution. So, to avoid this kind of situation, it's better to use "disable LABEL" statement.
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Above code works fine with a single instance of that class. But when there are multiple instances of the same class in the test-bench and all the instances are executing their threads simultaneously then the simulation will stop after executing "disable LABEL" statement of any instance.
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There are two ways to handle these kind of situations.
1) Limiting scope of "disable fork" by adding one extra hierarchy of fork...join.
2) Using "process" class of SystemVerilog

Let's see both ways through example,
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