#ifndef _LINUX_SEM_H
#define _LINUX_SEM_H
#include <linux/ipc.h>

/* semop flags */
#define SEM_UNDO        0x1000  /* undo the operation on exit */

/* semctl Command Definitions. */
#define GETPID  11       /* get sempid */
#define GETVAL  12       /* get semval */
#define GETALL  13       /* get all semval's */
#define GETNCNT 14       /* get semncnt */
#define GETZCNT 15       /* get semzcnt */
#define SETVAL  16       /* set semval */
#define SETALL  17       /* set all semval's */

/* One semid data structure for each set of semaphores in the system. */
struct semid_ds {
  struct ipc_perm sem_perm;            /* permissions .. see ipc.h */
  time_t          sem_otime;           /* last semop time */
  time_t          sem_ctime;           /* last change time */
  struct sem      *sem_base;           /* ptr to first semaphore in array */
  struct sem_queue *sem_pending;       /* pending operations to be processed */
  struct sem_queue **sem_pending_last; /* last pending operation */
  struct sem_undo *undo;	       /* undo requests on this array */
  ushort          sem_nsems;           /* no. of semaphores in array */
};

/* semop system calls takes an array of these. */
struct sembuf {
  ushort  sem_num;        /* semaphore index in array */
  short   sem_op;         /* semaphore operation */
  short   sem_flg;        /* operation flags */
};

/* arg for semctl system calls. */
union semun {
  int val;			/* value for SETVAL */
  struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */
  ushort *array;		/* array for GETALL & SETALL */
  struct seminfo *__buf;	/* buffer for IPC_INFO */
  void *__pad;
};

struct  seminfo {
    int semmap;
    int semmni;
    int semmns;
    int semmnu;
    int semmsl;
    int semopm;
    int semume;
    int semusz;
    int semvmx;
    int semaem;
};

#define SEMMNI  128             /* ?  max # of semaphore identifiers */
#define SEMMSL  32              /* <= 512 max num of semaphores per id */
#define SEMMNS  (SEMMNI*SEMMSL) /* ? max # of semaphores in system */
#define SEMOPM  32	        /* ~ 100 max num of ops per semop call */
#define SEMVMX  32767           /* semaphore maximum value */

/* unused */
#define SEMUME  SEMOPM          /* max num of undo entries per process */
#define SEMMNU  SEMMNS          /* num of undo structures system wide */
#define SEMAEM  (SEMVMX >> 1)   /* adjust on exit max value */
#define SEMMAP  SEMMNS          /* # of entries in semaphore map */
#define SEMUSZ  20		/* sizeof struct sem_undo */

#ifdef __KERNEL__

/* One semaphore structure for each semaphore in the system. */
struct sem {
  short   semval;         /* current value */
  short   sempid;         /* pid of last operation */
};

/* ipcs ctl cmds */
#define SEM_STAT 18
#define SEM_INFO 19

/* One queue for each semaphore set in the system. */
struct sem_queue {
    struct sem_queue *	next;	 /* next entry in the queue */
    struct sem_queue **	prev;	 /* previous entry in the queue, *(q->prev) == q */
    struct wait_queue *	sleeper; /* sleeping process */
    struct sem_undo *	undo;	 /* undo structure */
    int    		pid;	 /* process id of requesting process */
    int    		status;	 /* completion status of operation */
    struct semid_ds *	sma;	 /* semaphore array for operations */
    struct sembuf *	sops;	 /* array of pending operations */
    int			nsops;	 /* number of operations */
};

/* Each task has a list of undo requests. They are executed automatically
 * when the process exits.
 */
struct sem_undo {
    struct sem_undo *  proc_next; /* next entry on this process */
    struct sem_undo *  id_next;	  /* next entry on this semaphore set */
    int		       semid;	  /* semaphore set identifier */
    short *	       semadj;	  /* array of adjustments, one per semaphore */
};

asmlinkage int sys_semget (key_t key, int nsems, int semflg);
asmlinkage int sys_semop (int semid, struct sembuf *sops, unsigned nsops);
asmlinkage int sys_semctl (int semid, int semnum, int cmd, union semun arg);

#endif /* __KERNEL__ */

#endif /* _LINUX_SEM_H */
