#include<stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#define CLE 253
#define CLES 300

int main()
{
int shmid,semid;
char *mem;
int varlocale;

struct sembuf operation;

/* recuperation du segment de memoire partagee avec la cle CLE */

shmid=shmget((key_t)CLE,1000,0);

/* attachement*/

mem=shmat(shmid,NULL,0);

/* recuperation du tableau de semaphores*/

semid= semget((key_t)CLES,2,0);

/* operation P(MUTEX) (semaphore MUTEX est le deuxieme element du tableau */

operation.sem_num= 1;
operation.sem_op = -1;
operation.sem_flg= 0;
semop(semid, &operation, 1);

/* increment et test de NL */

*mem= *mem+ 1;

if (*mem== 1) 
{ 
  /* P(ACCES) */
  /* operation P (ACCES)*/

  operation.sem_num= 0;
  operation.sem_op= -1;
  operation.sem_flg= 0;
  semop(semid, &operation, 1);
  }
  
  /* operation V(MUTEX) (semaphore MUTEX est le deuxieme element du tableau */

  operation.sem_num= 1;
  operation.sem_op = 1;
  operation.sem_flg= 0;
  
  semop(semid, &operation, 1);




/* lecture dans le segment */

varlocale= *(mem+4);

printf ("lecteur:");
printf ("valeur mem %d ",*mem);
printf ("valeur memoire %d \n", varlocale);

//printf ("lecteur, valeur memoire %d \n", varlocale);

/* operation P(MUTEX) (semaphore MUTEX est le deuxieme element du tableau */

operation.sem_num= 1;
operation.sem_op = -1;
operation.sem_flg= 0;
semop(semid, &operation, 1);

/* decrementet test de NL */

*mem= *mem-1;
if (*mem== 0) 
{ /* V(ACCES) */
/* operationV (ACCES)*/

operation.sem_num= 0;
operation.sem_op= 1;
operation.sem_flg= 0;
semop(semid, &operation, 1);}

/* operation V(MUTEX) (semaphore MUTEX est le deuxieme element du tableau */

operation.sem_num= 1;
operation.sem_op = 1;
operation.sem_flg= 0;
semop(semid, &operation, 1);

return 0;
}