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#include <u.h>
#include <libc.h>
#include <thread.h>
#include <venti.h>
#include <diskfs.h>
#include "queue.h"
Queue*
qalloc(void)
{
Queue *q;
q = vtmallocz(sizeof(Queue));
q->r.l = &q->lk;
return q;
}
Block*
qread(Queue *q, u32int *pbno)
{
Block *db;
u32int bno;
qlock(&q->lk);
while(q->nel == 0 && !q->closed)
rsleep(&q->r);
if(q->nel == 0 && q->closed){
qunlock(&q->lk);
return nil;
}
db = q->el[q->ri].db;
bno = q->el[q->ri].bno;
if(++q->ri == MAXQ)
q->ri = 0;
if(q->nel-- == MAXQ/2)
rwakeup(&q->r);
qunlock(&q->lk);
*pbno = bno;
return db;
}
void
qwrite(Queue *q, Block *db, u32int bno)
{
qlock(&q->lk);
while(q->nel == MAXQ)
rsleep(&q->r);
q->el[q->wi].db = db;
q->el[q->wi].bno = bno;
if(++q->wi == MAXQ)
q->wi = 0;
if(q->nel++ == MAXQ/2)
rwakeup(&q->r);
qunlock(&q->lk);
}
void
qclose(Queue *q)
{
qlock(&q->lk);
q->closed = 1;
rwakeup(&q->r);
qunlock(&q->lk);
}
void
qfree(Queue *q)
{
vtfree(q);
}
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