Question $1$: Read$-$Write Semaphore $($Max Mark: $30/100)$ This question requires you to implement Read$-$Write semaphores for xv$6.$ Two files $$ semaphore.h and semaphore.c are provided for you as a reference design for semaphore implementation in xv$6.$ A structure representing a semaphore is defined in semaphore.h$.$ There are three functions associated with the semaphore $$ initsema$(),$ downsema$()$ and upsema$(),$ that initialize, decrement and increment a semaphore respectively. The code for these functions is provided in semaphore.c$.$ Study them in conjunction with the lecture slides to make sure you understand them. You may want to compile them with the xv$6$ kernel and see how it works with the user program sematest.c provided for you. In order to do so$,$ add the function provided in sys$\_$sematest.c to sysfile.c and make sematest$()$ a system call for xv$6$ in the usual way. Then compile xv$6$ with make qemu CPUS$=1$ and run sematest. Running xv$6$ on a single CPU prevents the displayed messages from being garbled. Task: Implement Read$-$Write Semaphore that can be used to solve the Reader$/$Writer problem as discussed in class. In semaphore.h there is already an empty struct rwsemaphore. There are also five associated function prototypes: void initrwsema$($struct rwsemaphore $*$rws$)$; int downreadsema$($struct rwsemaphore $*$rws$)$; int upreadsems$($struct rwsemaphore $*$rws$)$; void downwritesema$($struct rwsemaphore $*$rws$)$; void upwritesema$($struct rwsemaphore $*$rws$)$; You will need to design an appropriate struct rwsemaphore, and implement these five functions in semaphore.c$.$ Your struct rwsemaphore should be defined using the semaphore in semaphore.c$.$ That is$,$ do not use the xv$6$ locks. Note $2024$ AUT $2$ that you do not need to wake up the waiting threads$/$processes in the same order as semaphores are requested. There is a function called sys$\_$rwsematest$()$ in sys$\_$sematest.c$.$ Make rwsematest$()$ a system call like sematest$()$ above. A user test program has been provided in rwsematest.c$.$ It makes use of this system call. The test program conducts three tests $$ read lock test, write lock test, and read & write lock test. You will need to work out from this program what the correct output of each test should be$.$ Capture your test output and paste it into a document. Then explain why this output shows that your implementation is correct.