Problem $2$: In lecture $7,$ we have described the solution to Dining$-$Philosophers Problem that avoid the deadlock in C$.$ Complete the following code that uses semaphore.

#include

#include

#include

#define N $5$

#define THINKING $2$

#define HUNGRY $1$

#define EATING $0$

#define LEFT $($phnum $+4)\%$ N

#define RIGHT $($phnum $+1)\%$ N

int state$[$N$]$;

int phil$[$N$]=\{0,1,2,3,4\}$;

sem$\_$t mutex;

sem$\_$t S$[$N$]$;

void test$($int phnum$)\{$

if $($state$[$phnum$]==$ HUNGRY

&& state$[$LEFT$]!=$ EATING

&& state$[$RIGHT$]!=$ EATING$)\{$

$//$ state that eating

state$[$phnum$]=$ EATING;

sleep$(2)$;

printf$("$Philosopher $\%$d takes fork $\%$d and $\%$d

$",$

phnum $+1,$ LEFT $+1,$ phnum $+1)$;

printf$("$Philosopher $\%$d is Eating

$",$ phnum $+1)$;

sem$\_$post$($&S$[$phnum$])$;

$\}$

$\}$

$//$ take up chopsticks

void take$\_$fork$($int phnum$)\{$

$//$TODO: use semaphore wait

$//$ state that hungry

state$[$phnum$]=$ HUNGRY;

printf$("$Philosopher $\%$d is Hungry

$",$ phnum $+1)$;

$//$ eat if neighbours are not eating

test$($phnum$)$;

$//$TODO : use semaphore post

$//$ if unable to eat wait to be signalled

sem$\_$wait$($&S$[$phnum$])$; $//$ Noting to do here

sleep$(1)$;

$\}$

$//$ put down chopsticks

void put$\_$fork$($int phnum$)\{$

$//$ TODO: use semaphore wait

$//$ state that thinking

state$[$phnum$]=$ THINKING;

printf$("$Philosopher $\%$d putting fork $\%$d and $\%$d down

$",$

phnum $+1,$ LEFT $+1,$ phnum $+1)$;

printf$("$Philosopher $\%$d is thinking

$",$ phnum $+1)$;

test$($LEFT$)$;

test$($RIGHT$)$;

$//$ TODO : use semaphore post

$\}$

void$*$ philosopher$($void$*$ num$)\{$

while $(1)\{$

int$*$ i $=$ num;

sleep$(1)$;

take$\_$fork$(*$i$)$;

sleep$(0)$;

put$\_$fork$(*$i$)$;

$\}$

$\}$

int main$()\{$

int i;

pthread$\_$t thread$\_$id$[$N$]$;

$//$ initialize the semaphores

sem$\_$init$($&mutex, $0,1)$;

for $($i $=0$; i $<$ N; i$++)$

sem$\_$init$($&S$[$i$],0,0)$;

for $($i $=0$; i $<$ N; i$++)\{$

$//$ create philosopher processes

pthread$\_$create$($&thread$\_$id$[$i$],$ NULL,

philosopher, &phil$[$i$])$;

printf$("$Philosopher $\%$d is thinking

$",$ i $+1)$;

$\}$

for $($i $=0$; i $<$ N; i$++)$

pthread$\_$join$($thread$\_$id$[$i$],$ NULL$)$;

$\}$