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31 lines
870 B
31 lines
870 B
6 years ago
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/* newqueue.c - newqueue */
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#include <xinu.h>
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/*------------------------------------------------------------------------
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* newqueue - Allocate and initialize a queue in the global queue table
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*------------------------------------------------------------------------
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*/
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qid16 newqueue(void)
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{
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static qid16 nextqid=NPROC; /* Next list in queuetab to use */
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qid16 q; /* ID of allocated queue */
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q = nextqid;
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if (q >= NQENT) { /* Check for table overflow */
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return SYSERR;
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}
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nextqid += 2; /* Increment index for next call*/
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/* Initialize head and tail nodes to form an empty queue */
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queuetab[queuehead(q)].qnext = queuetail(q);
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queuetab[queuehead(q)].qprev = EMPTY;
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queuetab[queuehead(q)].qkey = MAXKEY;
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queuetab[queuetail(q)].qnext = EMPTY;
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queuetab[queuetail(q)].qprev = queuehead(q);
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queuetab[queuetail(q)].qkey = MINKEY;
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return q;
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}
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