- Well what’s a queue? A First In First Out data structure. Coming to system verilog, here comes the basic properties of Queues.
- The size of queue will be infinite by default. (Well until your simulator or your machine crashes)
- A fixed size queue.
- In any case the simulator will manage the modifications to this queue. May it be any additions or deletions of elements or updations to its elements.
- Now how do you declare a queue in system verilog. The syntax is not too complicated yet.
- Unbounded or an infinite queue.
- <data-type> <queue_identifier>[$]
- Eg:
int id_que[$]; - This will create a queue of name id_queue which can hold integer objects. Now int can be replaced by data type of your own choice
- Bounded or a finite queue.
- In this case if you don’t want to waste space and you know your queue does not need more than N number of elements you can use bounded queues.
- <data-type> <queue_identifier>[$:<size>]
- Eg:
int id_que[$:9]; //This stores 10 elements - This will create a queue of size (size+1). it can store (size+1) elements in it.
- Unbounded or an infinite queue.
- Now having been declared and you have to make use of it.
- Tasks/Functions for queue:
- size():
- id_que.size(): will return the number of elements present in the queue at the time when this is called.
- insert():
- id_que.insert(10, 1001); This will insert 1001 into queue at index 10.
- delete()
- id_que.delete(10): This will delete 10th element in the queue.
- push_back()
- id_que.push_back(VALUE) : This will append VALUE at the end of the queue. The pushed value is the tail or last element in the queue.
- push_front()
- id_que.push_front(VALUE): This will prepend VALUE at the beginning of the queue. The pushed value is the head or first element in the queue.
- pop_back():
- int a = id_queue.pop_back(): This will remove last element or tail from the queue and returns the value stored.
- pop_front()
- int b = id_que.pop_front(): This will remove the first element or the head from the queue and returns the value stored in first lement.
- size():
- Trivia:
- what happens when you pop from empty queue?
- what happens from when you push when queue is full?
- what happens if you push a wrong data type?
- what happens if you pop and assign to a wrong data type?
- Some practice:
- How do you implement mailbox functionality by using only queue and its methods
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