KERNEL DESIGN ISSUES - Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications - page 369

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head index

p q

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Figure 10.12 Inserting a TCB in a queue.

/*-----------------------------------------------------------*/
/* insert -- a task in a queue based on its deadline */
/*-----------------------------------------------------------*/
void

insert (proc i, queue *que)

long

dl; /* deadline of the task to be inserted */

int p; /* pointer to the previous TCB */

int q; /* pointer to the next TCB */

p = NIL;
q = *que;
dl = vdes[i].dline;
/* find the element before the insertion point */
while ((q != NIL) && (dl >= vdes[q].dline)) {
p=q;
q = vdes[q].next;
if (p != NIL) vdes[p].next = i;
else *que = i;
if (q != NIL) vdes[q].prev = i;
vdes[i].next = q;
vdes[i].prev = p;

}