From 014e4c306c4765c65abf1f2ce879bebcdd8c7261 Mon Sep 17 00:00:00 2001
From: ticktock35 <ticktock35@e8e0d7a0-c8d9-11dd-a880-a1081c7ac358>
Date: Mon, 15 Dec 2008 00:32:34 -0500
Subject: opkg: implement active_list_prev and test cases.

git-svn-id: http://opkg.googlecode.com/svn/trunk@169 e8e0d7a0-c8d9-11dd-a880-a1081c7ac358
---
diff --git a/libopkg/active_list.c b/libopkg/active_list.c
index 800915d..e297cfc 100644
--- a/libopkg/active_list.c
+++ b/libopkg/active_list.c
@@ -30,26 +30,47 @@ void active_list_init(struct active_list *ptr) {
  */ 
 struct active_list * active_list_next(struct active_list *head, struct active_list *ptr) {
     struct active_list *next=NULL;
-    if (!head) {
-        fprintf(stderr, "active_list_prev head = %p, ptr = %p invalid value!!\n", head, ptr);
+    if ( !head ) {
+        fprintf(stderr, "active_list_next head = %p, ptr = %p invalid value!!\n", head, ptr);
         return NULL;
     }
-    if (!ptr)
+    if ( !ptr )
         ptr = head;
     next = list_entry(ptr->node.next, struct active_list, node);
-    if (next == head ) {
+    if ( next == head ) {
         return NULL;
     }
-    if (ptr->depended && &ptr->depended->depend == ptr->node.next ) {
+    if ( ptr->depended && &ptr->depended->depend == ptr->node.next ) {
         return ptr->depended;
     }
-    while (next->depend.next != &next->depend) {
+    while ( next->depend.next != &next->depend ) {
         next = list_entry(next->depend.next, struct active_list, node); 
     }
     return next;
 }
 
 
+struct active_list * active_list_prev(struct active_list *head, struct active_list *ptr) {
+    struct active_list *prev=NULL;
+    if ( !head ) {
+        fprintf(stderr, "active_list_prev head = %p, ptr = %p invalid value!!\n", head, ptr);
+        return NULL;
+    }
+    if ( !ptr )
+        ptr = head;
+    if ( ptr->depend.prev != &ptr->depend ) {
+        prev = list_entry(ptr->depend.prev, struct active_list, node);
+        return prev;
+    } 
+    if ( ptr->depended  && ptr->depended != head && &ptr->depended->depend == ptr->node.prev ) {
+        prev = list_entry(ptr->depended->node.prev, struct active_list, node);
+    } else 
+        prev = list_entry(ptr->node.prev, struct active_list, node);
+    if ( prev == head )
+        return NULL;
+    return prev;
+}
+
 void active_list_clear(struct active_list *head) {
 }
 
diff --git a/libopkg/active_list.h b/libopkg/active_list.h
index 79ab77d..262164a 100644
--- a/libopkg/active_list.h
+++ b/libopkg/active_list.h
@@ -26,10 +26,13 @@ struct active_list {
     struct active_list *depended;
 };
 
-struct active_list * active_list_next(struct active_list *head, struct active_list *ptr);
 void active_list_init(struct active_list *ptr);
 void active_list_clear(struct active_list *head);
 void active_list_add_depend(struct active_list *node, struct active_list *depend);
 void active_list_add(struct active_list *head, struct active_list *node);
 
+struct active_list * active_list_next(struct active_list *head, struct active_list *ptr);
+
+struct active_list * active_list_prev(struct active_list *head, struct active_list *ptr);
+
 #endif
diff --git a/tests/opkg_active_list_test.c b/tests/opkg_active_list_test.c
index f7bd390..1e21645 100644
--- a/tests/opkg_active_list_test.c
+++ b/tests/opkg_active_list_test.c
@@ -48,7 +48,8 @@ void active_test_add_depend(struct active_test *A, struct active_test *B) {
              |_M      |_O
 
 Then the sequence will be 
-G M H I O J A B K N L C D E F
++: G M H I O J A B K N L C D E F
+-: F E D C L N K B A J O I H M G
 */
 void make_list(struct active_list *head) {
     struct active_test *A = active_test_new("A");
@@ -100,16 +101,17 @@ int main (void) {
     active_list_init(&head);
     make_list(&head);
 
+    printf("pos order: ");
     for(ptr = active_list_next(&head, &head); ptr ;ptr = active_list_next(&head, ptr)) {
         test = list_entry(ptr, struct active_test, list);
         printf ("%s ",test->str);
     }
-    printf("\n");
-    for(ptr = active_list_next(&head, &head); ptr ;ptr = active_list_next(&head, ptr)) {
+    printf("\nneg order: ");
+    for(ptr = active_list_prev(&head, &head); ptr ;ptr = active_list_prev(&head, ptr)) {
         test = list_entry(ptr, struct active_test, list);
         printf ("%s ",test->str);
     }
-    printf("\n");
+    printf("\npos order: ");
     for(ptr = active_list_next(&head, NULL); ptr ;ptr = active_list_next(&head, ptr)) {
         test = list_entry(ptr, struct active_test, list);
         printf ("%s ",test->str);
--
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