Implementing the General Semaphore

G$,$ Slide $8$

struct semaphore $($

int value $=$initial value$>$;

boolean mutex $=$ FALSE;

boolean hold $=$ TRUE;

shared struct semaphore s;

P $($struct semaphore s$)$ f

L$1$

while $($TS $(.$mutex$))$ ;

s$.$ value$--$;

L$3$

L$4$

if$($s$.$value $<0)$ f

s$-$mutex $=$ FALSE;

L$5$

while $($TS $($s$.$hold$))$ :

$\}$

else

L$6$

$\}$

s$.$mutex $=$ FALSE;

V $($struct semaphore s$)($ L$7$ while $($TS $($s$.$mutex$))$ ;

L$8$ s$.$value$++$;

$19$ if$($s$.$value $<=0)1$

L$10$

while $(!$s$.$hold$)$

;

L$11$

s$.$hold $=$ FALSE;

$\}$

L$12$

$\}$

s$.$mutex $=$ FALSE;

$6.$ We have discussed the above solution to implement a general semaphore.

$1.$ What is the purpose of LI$?(5$ points$)$

$2.$ What is the purpose of LS$?(5$ points$)$