/* simphil.h 		dining philosophers using simultaneous ops. 
			Author : Neil Dunstan, UNE, Australia */

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>

int forks;



/*	semsettran	will return the semaphore set id (system wide) of the
			key you give with sems in the set. If no semaphore set 
			has been established for this key, one is created */
int semsettran( int key, int sems ) {	/* translate/ create semaphore key to id */
  int sid;

  if( (sid = semget( (key_t)key, sems, 0666 | IPC_CREAT )) == -1 )
    printf( "semget" );
  return( sid );
}

/*	SimOps		the semaphore signal operation. sid must be the system
			wide semaphore number returned by semtran above	*/
void SimOps( int sid, int snum1, int snum2, int op ) {/* apply ops on sems simultaneously */
  struct sembuf sb[2];

  sb[0].sem_num = snum1; sb[1].sem_num = snum2;
  sb[0].sem_op = sb[1].sem_op = op;
  sb[0].sem_flg = sb[1].sem_flg = 0;
  if( semop( sid, sb, 2 ) == -1 )
    printf( "semop" );
}

/*	rm_sem		remove a semaphore from the system. sid must be the
			system wide semaphore returned from semtran	*/
void rm_sem( int sid ){	/* remove semaphore */
  (void)semctl( sid, 0, IPC_RMID, 0 );
}

void set_the_table() {
  forks = semsettran( IPC_PRIVATE, 5 );
}