Argument passing in JavaScript XPConnect

[shadows]

Hi,
I have the following C++ function:

bool test(BYTE *bpBuffer,DWORD iBufferLength) {
    // write into Buffer
    // write new value into BufferLenght
}

Is this XPIDL definition right?

boolean test(out octet bBuffer, inout unsigned long bBufferLength)

And how would I pass arguments from JavaScript?
I tryed:
...
...
var Buffer=new Object();
var BufferLength=new Object();
BufferLength.value=100;
test(Buffer,BufferLength);

But I get a Memory Exception saying that "read" can't be executed in memory
0x0000004 or something like that...

Thanx for any help