Imported Upstream version 2.6upstream/2.6upstream

1 files changed, 102 insertions, 0 deletions

diff --git a/lru.c b/lru.c
new file mode 100644
index 0000000..7fe2cc5
--- /dev/null
+++ b/lru.c
@@ -0,0 +1,102 @@
+/* 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