/*------------------------------------------------------------------------
* copyqueue - Move the internal queue linked list of pids from one
* queue to another by pointing the internal list at the other queue's
* first and last id's. Any contents in the destination queue will be
* dequeued first, and the source queue head and tail will be linked to
* make the source queue empty.
*------------------------------------------------------------------------
*/
void copyqueue(qid16 srcq, qid16 destq) {
while(!isempty(destq)) dequeue(destq);
qid16 firstid = firstid(srcq);
qid16 lastid = lastid(srcq);
firstid(srcq) = queuetail(srcq);
lastid(srcq) = queuehead(srcq);
firstid(destq) = firstid;
queuetab[firstid].qprev = queuehead(destq);
lastid(destq) = lastid;
queuetab[lastid].qnext = queuetail(destq);
}
pid32 getlast(qid16 qid)
{
if(isbadqid(qid))
{
return EMPTY;
}
return getitem(lastid(qid));
}
pid32 enqueue(pid32 pid, qid16 qid)
{
if(isbadpid(pid) || isbadqid(qid))
{
return SYSERR;
}
qid16 prev, tail;
prev = lastid(qid);
tail = queuetail(qid);
queuetab[pid].qprev = prev;
queuetab[pid].qnext = tail;
queuetab[prev].qnext = pid;
queuetab[tail].qprev = pid;
return pid;
}
