1) Add new BaseLib API GetPreviousNode()

2) Clarify comment for the value returned from GetNextNode() if the end of list is reached.


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9464 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 37 insertions, 2 deletions

diff --git a/MdePkg/Library/BaseLib/LinkedList.c b/MdePkg/Library/BaseLib/LinkedList.c
index 3ff582a978..0c811b0bff 100644
--- a/MdePkg/Library/BaseLib/LinkedList.c
+++ b/MdePkg/Library/BaseLib/LinkedList.c
@@ -276,8 +276,7 @@ GetFirstNode (
   @param  List  A pointer to the head node of a doubly linked list.

   @param  Node  A pointer to a node in the doubly linked list.

 

-  @return Pointer to the next node if one exists. Otherwise a null value which

-          is actually List is returned.

+  @return Pointer to the next node if one exists. Otherwise List is returned.

 

 **/

 LIST_ENTRY *

@@ -296,6 +295,42 @@ GetNextNode (
 }

 

 /**

+  Retrieves the previous node of a doubly linked list.

+ 

+  Returns the node of a doubly linked list that precedes Node.  

+  List must have been initialized with INTIALIZE_LIST_HEAD_VARIABLE()

+  or InitializeListHead().  If List is empty, then List is returned.

+ 

+  If List is NULL, then ASSERT().

+  If Node is NULL, then ASSERT().

+  If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or 

+  InitializeListHead(), then ASSERT().

+  If PcdMaximumLinkedListLenth is not zero, and List contains more than

+  PcdMaximumLinkedListLenth nodes, then ASSERT().

+  If PcdVerifyNodeInList is TRUE and Node is not a node in List, then ASSERT().

+ 

+  @param  List  A pointer to the head node of a doubly linked list.

+  @param  Node  A pointer to a node in the doubly linked list.

+ 

+  @return Pointer to the previous node if one exists. Otherwise List is returned.

+ 

+**/

+LIST_ENTRY *

+EFIAPI

+GetPreviousNode (

+  IN      CONST LIST_ENTRY          *List,

+  IN      CONST LIST_ENTRY          *Node

+  )

+{

+  //

+  // ASSERT List not too long and Node is one of the nodes of List

+  //

+  ASSERT (InternalBaseLibIsNodeInList (List, Node, TRUE));

+ 

+  return Node->BackLink;

+}

+

+/**

   Checks to see if a doubly linked list is empty or not.

 

   Checks to see if the doubly linked list is empty. If the linked list contains