#include	<ssdef.h>
#include	<lckdef.h>
#include	<starlet.h>
#include	<stdio.h>
#include	<stdlib.h>
#include	<descrip.h>
#include	<string.h>
#include	<errno.h>
#include	<unistd.h>

struct	lk_status_block{
	short int	cnd,
			rsv;
	int		id;
	short int	val;
                        };

int	lock	(long	*lkid)
{
long	status;
long	tmob [ 2 ] = { -30000000, -1 };	/* delta time = 3 sec		*/
struct	lk_status_block	lksb;
$DESCRIPTOR(resnam,"RRL$RES00");	/* name of resource for       	*/
					/* SDA SHO LOCK/NAME=RRL$RESS00	*/
long	efn_t = 0,efn_l = 1,efn_blk;
long	reqidt = 1;

	/* 
	 * call LOCK service
	 */
	status = sys$enq(efn_l, LCK$K_EXMODE, &lksb, LCK$M_SYNCSTS,
                &resnam,0,0,0,0,0,0,0);
	if ( !(status & 1) )
		lib$signal(status);
	/*
	 * check for synchronous successful completion
	 */
	if ( status == SS$_SYNCH )
		{
		*lkid = lksb.id;
		return	status;
		}
	/* 
	 * setup Timer Expiration Request and wait for it or lock success
	 */
	status = sys$setimr(efn_t, tmob,0,reqidt,0);
	if ( !(status & 1) )
		lib$signal(status);
	status = sys$wflor   (0,(1<<efn_l) | (1<<efn_t));
	if ( !(status & 1) )
		lib$signal(status);
	/*
	 * cancel Timer Expiration Request
	 */
	status = sys$cantim(reqidt,0);
	if ( !(status & 1) )
		lib$signal(status);
   	/*
	 * read lock Event Flag Number
	 */
	status = sys$readef(0 ,&efn_blk);
	if ( !(status & 1) )
		lib$signal(status);
	/*
	 * check lock Event Flag Number if NOT set then canceling wait
	 */
	if ( !(efn_blk & (1<<efn_l)) )
		{
		sys$deq(lksb.id,0,0,0);
		if ( !(status & 1) )
			lib$signal(status);
		return	SS$_DEADLOCK;
		}
	/* 
	 * get Lock Status Block 
	 */
	status = sys$synch(efn_l, &lksb);
	if ( !(status & 1) )
		{
		lib$signal(status);
		status = sys$deq(lksb.id,0,0,0);
		if ( !(status & 1) )
			lib$signal(status);
		return	SS$_DEADLOCK;
		}		

	/* 
	 * check condition in Lock Status Block 
	 */
	if ( !(lksb.cnd & 1) )
		{
		status = sys$deq(lksb.id,0,0,0);
		if ( !(status & 1) )
			lib$signal(status);
		return	SS$_DEADLOCK;
		}		

	/*
	 * return LOCK ID and condition
	 */
	*lkid = lksb.id;
	return	lksb.cnd;
}

int	unlock	(long	lkid)
{
long	status;
	/*
	 * call UNLOCK
	 */
	status = sys$deq(lkid,0,0,0);
	if ( !(status & 1) )
		lib$signal(status);
	return	SS$_NORMAL;
}

void	main	(void)
{
long	status;
long	lkid = 0;

	while(1)
		{
		puts("Try lock.");
		status = lock	(&lkid);
		if ( !(status & 1) )
			lib$signal(status);
		printf("lkid = %x",lkid);
		sleep(2);

		if ( (status & 1) )
			{
			puts("Try unlock.");
			status = unlock	(lkid);
			if ( !(status & 1) )
				lib$signal(status);
			printf("lkid = %x",lkid);
			}
		}
}