/*
*******************************************************************************
*  Copyright (c) Martin Poole
*******************************************************************************
**
** WARNING !!  WARNING !! WARNING !! WARNING !! WARNING !! WARNING !!
**
** Any changes to be made to this file should first be checked with
** mplib1 source control for library integrity.
**
** mplib1 source control can be reached at  mplib1@quatermass.co.uk
** 
*
*  $Source: /home/cvs/cvsroot/onelan/onelan/src/mplib1/libsrc/bpo_lock.c,v $
*  $Author: mpoole $
*  $Date: 2002/10/07 09:37:37 $
*  $Revision: 1.2 $
*
*******************************************************************************
*
* Change History
*
* $Log: bpo_lock.c,v $
* Revision 1.2  2002/10/07 09:37:37  mpoole
* Initial checkin of mplib1-3.1.0
*
* Revision 1.1  2002/10/07 09:36:54  mpoole
* Initial checkin of mplib1-3.1.0
*
*
*******************************************************************************
*/

#ident "$Header: /home/cvs/cvsroot/onelan/onelan/src/mplib1/libsrc/bpo_lock.c,v 1.2 2002/10/07 09:37:37 mpoole Exp $"

/* ------------------------------------------------------------------
    Include files
   ------------------------------------------------------------------ */

#include <stdio.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>

#include <mplib1/mplib1_config.h>

#include <mplib1/fprintfile.h>
#include <mplib1/bpo_lock.h>
#include <include/bpo_lock_internal.h>
#include <mplib1/cfg_file.h>

/* ------------------------------------------------------------------
    defines
   ------------------------------------------------------------------ */

static int bpo_lock_debug=0;

/* ------------------------------------------------------------------
    Code starts here
   ------------------------------------------------------------------ */

#ifdef HAVE_MSEM
/* A number of functions to simulate the required primitives */
Xchg( b_lock_t *lockp )
{
    int rc;
    rc = msem_lock( lockp, MSEM_IF_NOWAIT );
    /* the call can fail, and return -1,
	if it is interrupted,
	if the lock is re-initialised
	or it is already locked (normal)
    */
    return(rc);
}

Clr( b_lock_t *lockp )
{
    int rc;
    rc = msem_unlock( lockp, MSEM_IF_NOWAIT );

}
#endif

long
b_Lockval( b_lock_t *lockp )
{
#ifdef HAVE_PTHREADS
    int rc;
    rc = pthread_mutex_trylock( &lockp->mp );
	if (rc==0)
		pthread_mutex_unlock( &lockp->mp );
	return(rc);
#else
#ifdef HAVE_MSEM
    int rc;
    rc = msem_lock( lockp, MSEM_IF_NOWAIT );
    if (rc==0)
	msem_unlock( lockp, 0 );
    return(rc);
#else
#ifdef Lckval
    return( Lckval(lockp));
#else
    int rc;
    rc = Xchg( lockp );
    if (rc==0)
	Clr( lockp );
    return(rc);
#endif
#endif
#endif
}

int
b_TryLock( b_lock_t *lockp )
{
    int rc;
#ifdef HAVE_PTHREADS
    rc = pthread_mutex_trylock( &lockp->mp );
#else
#ifdef HAVE_MSEM
    rc = msem_lock( lockp, MSEM_IF_NOWAIT );
#else
    rc = Xchg(lockp);
#endif
#endif
    return(rc);
}

void
b_Lock( b_lock_t *lockp )
{
    int lc=0;
    bpo_lock_debug = get_config_flag("BPO_LOCK_DEBUG");
#ifdef HAVE_PTHREADS
    pthread_mutex_lock( &lockp->mp );
#else
#ifdef HAVE_MSEM
    msem_lock( lockp, 0 );
#else
    while ( Xchg(lockp) )
    {
	bpo_take_a_nap();
	if (bpo_lock_debug && lc==0)
	{
	    lc++;
	    fprintfile(stderr,"b_Lock: Awaiting lock %p\n", lockp );
	}
    };
#endif
#endif
    return;
}

void
b_Unlock( b_lock_t *lockp )
{
#ifdef HAVE_PTHREADS
    pthread_mutex_unlock( &lockp->mp );
#else
#ifdef HAVE_MSEM
    msem_unlock( lockp, 0 );
#else
    Clr( lockp );
#endif
#endif
    return;
}

void
b_Init( b_lock_t *lockp )
{
#ifdef HAVE_PTHREADS
#ifdef HAVE_PTHREADS_DCE
    pthread_mutexattr_create( &lockp->mattr );
    pthread_mutexattr_setkind_np( &lockp->mattr, MUTEX_FAST_NP );
    pthread_mutex_init( &lockp->mp, lockp->mattr );
#else
    pthread_mutexattr_init( &lockp->mattr );
    pthread_mutexattr_setpshared( &lockp->mattr, PTHREAD_PROCESS_SHARED );
    pthread_mutex_init( &lockp->mp, &lockp->mattr );
#endif
#else
#ifdef HAVE_MSEM
    msem_init( lockp, MSEM_UNLOCKED );
#else
#ifdef HAVE_MUTEX
    init_lock( lockp );
#else
#ifdef HAVE_LWP_MUTEX
    memset( lockp, '\0', sizeof(b_lock_t) );
#else
    Clr( lockp );
#endif
#endif
#endif
#endif
    return;
}

/* -- End of File -- */