Simplify mpegplayer a bit and use array-based lists rather than linked lists for stream management. Move a couple useful functions to handle pointer arrays from kernel.c into general.c; mpeglayer now makes use of them.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26101 a1c6a512-1295-4272-9138-f99709370657

apps/plugins/mpegplayer/mpeg_misc.c

@@ -102,3 +102,63 @@ uint32_t muldiv_uint32(uint32_t multiplicand,
 
     return UINT32_MAX; /* Saturate */
 }
+
+
+/** Lists **/
+
+/* Does the list have any members? */
+bool list_is_empty(void **list)
+{
+    return *list == NULL;
+}
+
+/* Is the item inserted into a particular list? */
+bool list_is_member(void **list, void *item)
+{
+    return *rb->find_array_ptr(list, item) != NULL;
+}
+
+/* Removes an item from a list - returns true if item was found
+ * and thus removed. */
+bool list_remove_item(void **list, void *item)
+{
+    return rb->remove_array_ptr(list, item) != -1;
+}
+
+/* Adds a list item, insert last, if not already present. */
+void list_add_item(void **list, void *item)
+{
+    void **item_p = rb->find_array_ptr(list, item);
+    if (*item_p == NULL)
+        *item_p = item;
+}
+
+/* Clears the entire list. */
+void list_clear_all(void **list)
+{
+    while (*list != NULL)
+        *list++ = NULL;
+}
+
+/* Enumerate all items in the array, passing each item in turn to the
+ * callback as well as the data value. The current item may be safely
+ * removed. Other changes during enumeration are undefined. The callback
+ * may return 'false' to stop the enumeration early. */
+void list_enum_items(void **list,
+                     list_enum_callback_t callback,
+                     intptr_t data)
+{
+    for (;;)
+    {
+        void *item = *list;
+
+        if (item == NULL)
+            break;
+
+        if (callback != NULL && !callback(item, data))
+            break;
+
+        if (*list == item)
+            list++; /* Item still there */
+    }
+}