semaphor.c

/*
 *  SMAPI; Modified Squish MSGAPI
 *
 *  Squish MSGAPI0 is copyright 1991 by Scott J. Dudley.  All rights reserved.
 *  Modifications released to the public domain.
 *
 *  Use of this file is subject to the restrictions contain in the Squish
 *  MSGAPI0 licence agreement.  Please refer to licence.txt for complete
 *  details of the licencing restrictions.  If you do not find the text
 *  of this agreement in licence.txt, or if you do not have this file,
 *  you should contact Scott Dudley at FidoNet node 1:249/106 or Internet
 *  e-mail Scott.Dudley@f106.n249.z1.fidonet.org.
 *
 *  In no event should you proceed to use any of the source files in this
 *  archive without having accepted the terms of the MSGAPI0 licensing
 *  agreement, or such other agreement as you are able to reach with the
 *  author.
 */

#if defined (UNIX) || defined (__EMX__)
#include <unistd.h>
#endif
#include <stdlib.h> /* NULL */

#include "semaphor.h"

#if defined (NOSEMAPHORES)
/* No code for Non-Multitasking Systems */

#elif defined (__BEOS__)

void create_semaphore(SEMAPHORE * sem)
{
    *sem = create_sem(0, 0);
    release_sem(*sem);
}

void delete_semaphore(SEMAPHORE * sem)
{
    delete_sem(*sem);
}

void lock_semaphore(SEMAPHORE * sem)
{
    if(acquire_sem(*sem) != B_NO_ERROR)
    {
        snooze(10);
    }
}

void unlock_semaphore(SEMAPHORE * sem)
{
    release_sem(*sem);
}

#elif defined (UNIX)

#if ((defined (__FreeBSD__) || defined (__GNU_LIBRARY__)) && !defined (_SEM_SEMUN_UNDEFINED))
/* union semun is defined by including <sys/sem.h> */
#else
/* according to X/OPEN we have to define it ourselves */
union semun
{
    int                  val;    /* value for SETVAL */
    struct semid_ds *    buf;    /* buffer for IPC_STAT, IPC_SET */
    unsigned short int * array;  /* array for GETALL, SETALL */
    struct seminfo *     __buf;  /* buffer for IPC_INFO */
};

#endif

void create_semaphore(SEMAPHORE * sem)
{
    union semun fl;

    fl.val = 1;
    *sem   = semget(IPC_PRIVATE, 1, 0600 | IPC_CREAT);
    semctl(*sem, 0, SETVAL, fl);
}

void delete_semaphore(SEMAPHORE * sem)
{
    union semun fl;

    fl.val = 0;
    semctl(*sem, 0, IPC_RMID, fl);
}

void lock_semaphore(SEMAPHORE * sem)
{
    struct sembuf sops;

    sops.sem_num = 0;
    sops.sem_op  = -1;
    sops.sem_flg = 0;

    while(semop(*sem, &sops, 1))
    {
        usleep(10);
    }
}

void unlock_semaphore(SEMAPHORE * sem)
{
    struct sembuf sops;

    sops.sem_num = 0;
    sops.sem_op  = 1;
    sops.sem_flg = 0;
    semop(*sem, &sops, 1);
}

#elif defined (OS2)

#define INCL_DOS
#include <os2.h>


void create_semaphore(SEMAPHORE * s)
{
    DosCreateMutexSem(NULL, s, DC_SEM_SHARED, 0);
}

void lock_semaphore(SEMAPHORE * s)
{
    DosRequestMutexSem(*s, SEM_INDEFINITE_WAIT);
}

void unlock_semaphore(SEMAPHORE * s)
{
    DosReleaseMutexSem(*s);
}

void delete_semaphore(SEMAPHORE * s)
{
    DosCloseMutexSem(*s);
}

#endif /* if defined (NOSEMAPHORES) */