arraylist shifting

[tifoso]

I searched here and only found somebody with a round-robin arraylist issue here but what they suggest I tried already and it doesn't work for me I hope somebody can shed some light

Scenario: I'm porting a PalmOS App written on C to .NET initially for a desktop and then to the CF, generic stuff is not biggie I have a section where
data comes in bursts and updates an array on a LIFO way, in C using a Memcopy gets this done in a few lines and pretty quickly

Requirement is to do this in vb.net 2003 and it seemed straightforward and an arraylist was chosen for speed appending data as it comes is cool and it works good, once the full-size is reached it came the time to do the LIFO and here I'n having issues.

I looped thru the array , shiftting a page of data shows good in the debugger
for i= start_idx to max-1
arraylist(i-start_idx) = arraylis(i)

the page at the end of array needs to be blanked out and the cell structure
have an element that needs a value set before receiving the packet
here is the issue I tried (simplifying the data structure)

cur_elt =CType(arraylis t(j), WackyType)
cur_elt.elt1=va lue
cur_elt.other_e lts =Nothing ' a few here
arraylist(j) = cur_elt

It works until I hit up to the last elt when it blanks the whole array om the
other_elts fields and my shifting is gone, I tried RemoveAt and Add with worst behaviour, any suggestions????

I had it with a regular ARRAY but used arraylist for the advertised performance boost. memcopy is not easily available in NET and the API gets funny so didn't go any deeper thinking that the Arraylist would do it.

Grazie in advance

Ciao

[tifoso]

OK I also looked at the Queue and Stack but in this case accessing to elements in the middle e.g. elts starting at n thru n+mini_page positions seem to be available by the enumerator type but I'm not sure about the performance of those???

Any pointers here would be great. I still would like to get the Arraylist shifting as I can see it could useful somewhere else.

CIao