Type listnode
     As Any Ptr pData
     As listnode Ptr pNext
     As listnode Ptr pPrev
End Type

Declare Function ListCreate() As listnode Ptr
Declare Function ListAdd(list As listnode Ptr, item As Any Ptr) As Any Ptr
Declare Function ListAddHead(list As listnode Ptr, item As Any Ptr) As Any Ptr
Declare Function ListGetFirst(list As listnode Ptr) As listnode Ptr
Declare Function ListGetLast(list As listnode Ptr) As listnode Ptr
Declare Function ListGetNext(list As listnode Ptr) As listnode Ptr
Declare Function ListGetPrev(list As listnode Ptr) As listnode Ptr
Declare Function ListGetData(list As listnode Ptr) As Any Ptr
Declare Function ListRemove(list as listnode ptr, bDelete as integer = 0) as listnode ptr
Declare Function ListRemoveAll(list as listnode ptr, bDelete as integer = 0) As Integer

Dim As listnode Ptr list, node
Dim As Integer Ptr item
list = ListCreate()
item = ListAdd(list, CAllocate(Len(Integer)))
*item = 4
item = ListAdd(list, CAllocate(Len(Integer)))
*item = 44
item = ListAddHead(list, CAllocate(Len(Integer)))
*item = 56

item = 0 ' just to show it works
node = ListGetFirst(list)

While node <> 0
     Print "found item"
     item = ListGetData(node)
     Print *item
     node = ListRemove(node,1)
Wend

While Inkey$ = "" : Wend

' CREATE
Function ListCreate() As listnode Ptr
     Dim As listnode Ptr pTemp
     pTemp = CAllocate(Len(listnode))
     ' CAllocate automatically zeroes memory.

     Return pTemp
End Function

' ADD, ADDHEAD

Function ListAdd(list As listnode Ptr, item As Any Ptr) As Any Ptr
     Dim As listnode Ptr pTemp

     If (list = 0) Then Return item

     pTemp = ListGetLast(list)

     pTemp->pNext = CAllocate(Len(listnode))
     pTemp->pNext->pPrev = pTemp
     pTemp->pNext->pData = item

     Return item
End Function

Function ListAddHead(list As listnode Ptr, item As Any Ptr) As Any Ptr
     Dim As listnode Ptr pTemp

     If (list = 0) Then Return item
     pTemp = list->pNext ' сохраняем первый
     list->pNext = CAllocate(Len(listnode)) 'выделяем новый адрес для первого
     list->pNext->pPrev = list ' новый адрес для листа
     list->pNext->pData = item ' загоняем наш новый элемент
     list->pNext->pNext = pTemp  
     If (pTemp <> 0) Then
         pTemp->pPrev = list->pNext
     End If

     Return item
End Function

' GETFIRST, GETLAST

Function ListGetFirst(list As listnode Ptr) As listnode Ptr
     If (list = 0) Then Return 0

     Return list->pNext
End Function

Function ListGetLast(list As listnode Ptr) As listnode Ptr
     Dim As listnode Ptr pTemp

     If (list = 0) Then Return 0

     pTemp = list
     While (pTemp->pNext <> 0)
         pTemp = pTemp->pNext
     Wend

     Return pTemp
End Function

' GETNEXT, GETPREV

Function ListGetNext(list As listnode Ptr) As listnode Ptr
     If (list = 0) Then Return 0

     Return list->pNext
End Function

Function ListGetPrev(list As listnode Ptr) As listnode Ptr
     ' can't do anything to a null list
     If (list = 0) Then Return 0
     ' this is needed for below
     If (list->pPrev = 0) Then Return 0
     ' since the list starts with a null node (pPrev and pData = 0),
     ' the first should be the one right after the real first.
     If (list->pPrev->pPrev = 0) Then Return 0

     Return list->pPrev
End Function

' GETDATA

Function ListGetData(list As listnode Ptr) As Any Ptr
     If (list = 0) Then Return 0

     Return list->pData
End Function

' REMOVE, REMOVEALL

Function ListRemove(list as listnode ptr, bDelete as integer = 0) As listnode ptr
     Dim As listnode Ptr pPrev
     Dim As listnode Ptr pNext

     If (list = 0) Then Return 0

     pPrev = list->pPrev
     pNext = list->pNext

     If ((list->pData <> 0) And (bDelete <> 0)) Then Deallocate list->pData

     Deallocate list

     If (pPrev <> 0) Then
         pPrev->pNext = pNext
     End If
     If (pNext <> 0) Then
         pNext->pPrev = pPrev
     End If

     Return pNext
End Function

Function ListRemoveAll(list as listnode ptr, bDelete as integer = 0) As Integer
     Dim As listnode Ptr node

     node = list
     If (list = 0) Then Return 0

     While (node <> 0)
         If ((node->pData <> 0) And (bDelete <> 0)) Then Deallocate node->pData
         node = ListRemove(node)
     Wend

     Return 1
End Function