Import sources from 2011-03-30 iso image

1 files changed, 75 insertions, 0 deletions

diff --git a/sys/src/cmd/cfs/lru.c b/sys/src/cmd/cfs/lru.c
new file mode 100755
index 000000000..55f6c6e8b
--- /dev/null
+++ b/sys/src/cmd/cfs/lru.c
@@ -0,0 +1,75 @@
+/*
+ *  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;
+}