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/*
* lru lists are circular with a list head
* pointing to the start and end of the list
*/
#include <u.h>
#include "lru.h"
/*
* Create an lru chain of buffers
*/
void
lruinit(Lru *h)
{
h->lprev = h->lnext = h;
}
/*
* Add a member to an lru chain
*/
void
lruadd(Lru *h, Lru *m)
{
h->lprev->lnext = m;
m->lprev = h->lprev;
h->lprev = m;
m->lnext = h;
}
/*
* Move to end of lru list
*/
void
lruref(Lru *h, Lru *m)
{
if(h->lprev == m)
return; /* alread at end of list */
/*
* remove from list
*/
m->lprev->lnext = m->lnext;
m->lnext->lprev = m->lprev;
/*
* add in at end
*/
h->lprev->lnext = m;
m->lprev = h->lprev;
h->lprev = m;
m->lnext = h;
}
/*
* Move to head of lru list
*/
void
lruderef(Lru *h, Lru *m)
{
if(h->lnext == m)
return; /* alread at head of list */
/*
* remove from list
*/
m->lprev->lnext = m->lnext;
m->lnext->lprev = m->lprev;
/*
* add in at head
*/
h->lnext->lprev = m;
m->lnext = h->lnext;
h->lnext = m;
m->lprev = h;
}
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