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/* lru.c
* LRU cache
* (c) 2002 Karel 'Clock' Kulhavy
* This file is a part of the Links program, released under GPL.
*/
#include "cfg.h"
#ifdef G
#include "links.h"
void lru_insert(struct lru *cache, void *entry, struct lru_entry ** row,
unsigned bytes_consumed)
{
struct lru_entry *new_entry=mem_alloc(sizeof(*new_entry));
new_entry->above=NULL;
new_entry->below=cache->top;
new_entry->next=*row;
new_entry->previous=row;
new_entry->data=entry;
new_entry->bytes_consumed=bytes_consumed;
if (new_entry->below){
new_entry->below->above=new_entry;
}else{
cache->bottom=new_entry;
}
if (new_entry->next){
new_entry->next->previous=&(new_entry->next);
}
*row=new_entry;
cache->top=new_entry;
cache->bytes+=bytes_consumed;
cache->items++;
}
/* Returns bottom (or NULL if the cache is empty) but doesn't
* unlink it.
*/
void * lru_get_bottom(struct lru *cache)
{
if (!cache->bottom) return NULL;
return cache->bottom->data;
}
/* Destroys bottom on nonempty cache. If the cache is empty, segmentation
* fault results.
*/
void lru_destroy_bottom(struct lru* cache)
{
struct lru_entry *it=cache->bottom;
cache->bytes-=cache->bottom->bytes_consumed;
cache->items--;
cache->bottom=it->above;
if (cache->bottom) cache->bottom->below=NULL; else cache->top=NULL;
if (it->next){
it->next->previous=it->previous;
}
*(it->previous)=it->next;
mem_free(it);
}
/* Returns a value of "data"
* template is what we search for.
*/
void *lru_lookup(struct lru *cache, void *template, struct lru_entry *ptr)
{
while (ptr){
if (!cache->compare_function(ptr->data,template)){
/* Found */
if (ptr->above){
if (ptr->below){
ptr->below->above=ptr->above;
}else{
cache->bottom=ptr->above;
}
ptr->above->below=ptr->below;
ptr->above=NULL;
ptr->below=cache->top;
cache->top->above=ptr;
cache->top=ptr;
}
return ptr->data;
}
ptr=ptr->next;
}
return NULL;
}
void lru_init (struct lru *cache, int (*compare_function)(void *entry, void *template))
{
cache->compare_function=compare_function;
cache->top=NULL;
cache->bottom=NULL;
cache->bytes=0;
cache->items=0;
}
#endif
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