/*  check fifth fork...output is oppikable*/#include<stdio.h>#include<stdlib.h>#include<pthread.h>#include<sys/shm.h>#include<unistd.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#define N  5#define THINKING 1#define HUNGRY 2#define EATING 3#define uniqkey ftok("." , 'A') union semun 	{	int val;	struct semid_ds *buf;	ushort *array;	};int state[N];int semid,ret=0;  static struct sembuf acquire={0,-1,SEM_UNDO};  static struct sembuf release={0,1, SEM_UNDO}; static ushort initial[6]={6,5,4,3,2,1};	//its giving some error other wayunion semun arg; void initialize (void){	int ky=0;	for(ky;ky<N;ky++)		{		state[ky]=THINKING;		}}int left (int k)	{	return ((k+N-1)%N);	}int right (int k)	{	return ((k+1)%N);	}int randomizeme (int d)				//not used{	int lret;	ret=(ret +1)%5;	lret=ret*d - (ret+d);	if(lret<=0)		return 5;	else		return lret;}void printstate (void){	int ku=0;	for(ku;ku<5;ku++)		{		printf(" P%d --",ku);		switch (state[ku])			{			case 1 :				printf("THINKING ## ");break;			case 2 :				printf("HUNGRY ## ");break;			case 3 :				printf("EATING ## ");break;			default :				printf("invalid choice \n");			}		printf("\n");		}}int test (int ph){	if( (state[left(ph)]!=EATING) && (state[right(ph)]!=EATING) &&  (state[ph]==HUNGRY)  )		{			if(ph==0)			{			acquire.sem_num=5;			if(semop(semid,&acquire,1)==-1)				{				printf("error in acquiring %d \n",5);				}			}			else			{			acquire.sem_num=ph;			if(semop(semid,&acquire,1)==-1)				{				printf("error in acquiring %d \n",ph);				}			}			acquire.sem_num=(ph+1)%N;			if(semop(semid,&acquire,1)==-1)				{				printf("error in acquiring %d \n",(ph+1));				}			state[ph]=EATING;		return 1;		}	else		{return 0;}}void takeforks (int p){	int t;	if((p%2)==0)		{		state[p]=HUNGRY;		if(test(p))			{	//left right						sleep(2); //eating time					}		else			{			sleep(2);			takeforks(p);			}		}	else		{		state[p]=HUNGRY;		//sleep(1); 	 //randomness urapppilla		if(test(p))			{	//right left// 			acquire.sem_num=right(p);// 			if(semop(semid,&acquire,1)==-1)// 				{// 				printf("error in acquiring %d \n",right(p));// 				}// 			acquire.sem_num=left(p);// 			if(semop(semid,&acquire,1)==-1)// 				{// 				printf("error in acquiring %d \n",left(p));// 				}// 			state[p]=EATING;			sleep(2); //eating time					}		else			{			sleep(3);			takeforks(p);			}		}	//putdownforks(p);}void putdownforks (int r){	if(r==0)	{	release.sem_num=(5);	if(semop(semid,&release,1)==-1)				{				//printf("error in releasing %d \n",5);				}	}	else	{	release.sem_num=(r);	if(semop(semid,&release,1)==-1)				{				printf("error in releasing %d \n",r);				}	}	release.sem_num=(r+1);	if(semop(semid,&release,1)==-1)				{				printf("error in releasing %d \n",(r+1));				}	state[r]=THINKING;// 	if (test(r))// 	{// 	takeforks(left(r));putdownforks(r);// 	takeforks(right(r));putdownforks(r);// 	}}void * philosopher (void *num){	int n,ch=6;	n=(int) num;	printf("***%d \n",n);	if(n!=N)		{		if(semget(uniqkey,6,0)==-1)		//diff process should first access semaphore(no need 4 creation)			{			printf("error in accessing semaphores \n");			}						if((n%2)!=0)			{sleep(1);}					while(ch)			{// 			printf("[ %d #### %d ] \n",n,state[n]);			ch--; 			//printf()			takeforks(n);			putdownforks(n);			sleep(4);			}				}	else		{//for printing		ch=25;		while(ch)			{			printf("=====================================================\n");			sleep(1);			printstate();			ch--;			}		}	pthread_exit(NULL);}int main(){printf("ok\n");printf(" eshwara ithu work cheyyane \n");//printf("$$%d$$",left(0));//printf("$%d$",right(0));initialize();			//all philosophers are made to thinkarg.array=initial;		//not able to do globally! :(semid=semget(uniqkey,6,IPC_CREAT|IPC_EXCL|0666); //6 bcz i am using from 1 to 5...5 is enoughif(semid==-1)	{	printf("error in making semaphore \n");	}if(semctl(semid,0,SETALL,arg) == -1)	{	printf("error in initialization \n");	}//int po=555;pthread_t  phil ;int thread;int i=0;for(i;i<=N;i++)	{	thread=pthread_create(&phil,NULL,philosopher,(void *) i);	if(thread)		{		printf("error in creating threads \n");		}	}for(i=0;i<=N;i++)	{	pthread_join(phil,NULL);	}if(semctl(semid,0,IPC_RMID,0) ==-1)	{	printf("error in removing semaphores \n");	} printf("=======================THE END======================\n"); return 0;}