Computer Science OS Question: A synchronization mechanism consists of 2 atomic r

Question

Computer Science OS Question:

A synchronization mechanism consists of 2 atomic routines, ENQ(r) and DEQ(r). "r" is a resource variable that has two fields, inuse (boolean) and queue (a queue) which is a queue of processes waiting to acquire the resource. The definitions of ENQ and DEQ are:

ENQ(r) : if (r.inuse==1) then begin
                insert current process in r.queue
                block
              end
           else  r.inuse = 1;

DEQ(r) : if r.queue == nil then inuse = false
           else delete a process from r.queue and activate it.

Construct an implementation of ENQ/DEQ using semaphores. You can use other variables, etc that you need, but no other atomic code or synchronization constructs other than P or V can be used.

Please show work/explain!

Explanation / Answer

The resource is a Semaphore initialized to 1

P(r) = Enq(r)

V(r) = DEQ(r)

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