stos: ob: Add object cache groundwork

Signed-off-by: Chloe M. <chloe@mensia.org>

paw/stos/ob/cache.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description:  Object manager cache
+ * Author:       Chloe M.
+ */
+
+#include <ob/cache.h>
+#include <string.h>
+
+VOID
+ObReclaimToCache(OBJECT_CACHE *Cache, ST_OBJECT *Object)
+{
+    ST_OBJECT *Last;
+
+    if (Cache == NULL || Object == NULL) {
+        return;
+    }
+
+    /* Can only reclaim when refcount hits zero */
+    if (Object->RefCount != 0) {
+        return;
+    }
+
+    /* Insert the object */
+    Object->CacheNext = NULL;
+    if (Cache->First == NULL || Cache->Last == NULL) {
+        Cache->First = Object;
+        Cache->Last = Object;
+    } else {
+        Last = Cache->Last;
+        Last->CacheNext = Object;
+        Cache->Last = Object;
+    }
+
+    ++Cache->EntryCount;
+}
+
+VOID
+ObInitCache(OBJECT_CACHE *Cache)
+{
+    if (Cache == NULL) {
+        return;
+    }
+
+    Cache->EntryCount = 0;
+    Cache->First = NULL;
+    Cache->Last = NULL;
+}
+
+ST_OBJECT *
+ObPopFromCache(OBJECT_CACHE *Cache)
+{
+    ST_OBJECT *First;
+
+    if (Cache == NULL) {
+        return NULL;
+    }
+
+    First = Cache->First;
+    if (First == NULL) {
+        return NULL;
+    }
+
+    Cache->First = First->CacheNext;
+    RtlMemSet(First, 0, sizeof(*First));
+    return First;
+}