q.h,v

来自「TCP-IP红宝书源代码」· H,V 代码 · 共 68 行

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date	97.09.21.19.26.19;	author dls;	state Dist;
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date	94.05.10.20.48.46;	author dls;	state Old;
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@/* q.h - firstid, firstkey, isempty, lastkey, nonempty */

/* q structure declarations, constants, and inline procedures		*/

#ifndef	NQENT
#define	NQENT		NPROC + NSEM + NSEM + 4	/* for ready & sleep	*/
#endif

struct	qent	{		/* one for each process plus two for	*/
				/* each list				*/
	int	qkey;		/* key on which the queue is ordered	*/
	int	qnext;		/* pointer to next process or tail	*/
	int	qprev;		/* pointer to previous process or head	*/
	};

extern	struct	qent q[];
extern	int	nextqueue;

/* inline list manipulation procedures */

#define	isempty(list)	(q[(list)].qnext >= NPROC)
#define	nonempty(list)	(q[(list)].qnext < NPROC)
#define	firstkey(list)	(q[q[(list)].qnext].qkey)
#define lastkey(tail)	(q[q[(tail)].qprev].qkey)
#define firstid(list)	(q[(list)].qnext)

/* gpq constants */

#define	QF_WAIT		0	/* use semaphores to mutex		*/
#define	QF_NOWAIT	1	/* use disable/restore to mutex		*/
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