getitem.c,v

来自「TCP-IP红宝书源代码」· C,V 代码 · 共 75 行

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date	97.09.21.19.29.30;	author dls;	state Dist;
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date	94.05.06.03.12.23;	author dls;	state Works;
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@/* getitem.c - getfirst, getlast */

#include <conf.h>
#include <kernel.h>
#include <q.h>

/*------------------------------------------------------------------------
 * getfirst  --	 remove and return the first process on a list
 *------------------------------------------------------------------------
 */
int	getfirst(head)
	int	head;			/* q index of head of list	*/
{
	int	proc;			/* first process on the list	*/

	if ((proc=q[head].qnext) < NPROC)
		return( dequeue(proc) );
	else
		return(EMPTY);
}



/*------------------------------------------------------------------------
 * getlast  --  remove and return the last process from a list
 *------------------------------------------------------------------------
 */
int	getlast(tail)
	int	tail;			/* q index of tail of list	*/
{
	int	proc;			/* last process on the list	*/

	if ((proc=q[tail].qprev) < NPROC)
		return( dequeue(proc) );
	else
		return(EMPTY);
}
@


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