Implement tracking of available physical pages

xtoskrnl/mm/pfn.cc

@@ -60,6 +60,21 @@ MM::Pfn::ComputePfnDatabaseSize(VOID)
     PfnDatabaseSize >>= MM_PAGE_SHIFT;
 }
 
+/**
+ * Decrements the global count of available pages.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MM::Pfn::DecrementAvailablePages(VOID)
+{
+    /* Decrement the global count of available pages */
+    AvailablePages--;
+}
+
 /**
  * Retrieves the total number of physical pages managed by the system.
  *
@@ -90,6 +105,21 @@ MM::Pfn::GetPfnDatabaseSize(VOID)
     return PfnDatabaseSize;
 }
 
+/**
+ * Increments the global count of available pages.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MM::Pfn::IncrementAvailablePages(VOID)
+{
+    /* Increment the global count of available pages */
+    AvailablePages++;
+}
+
 /**
  * Scans memory descriptors provided by the boot loader.
  *