lock operation

[Manfred W. <e95...@st...>]

I have one question concerning libraw1394.
If I issue a lock operation, how can I find out response value. The
function has only (input-)arguments for arg and data, but no
(output-)argument for the data of the response (old value).
This is important, because after a compare_swap operation I have to
verify, if that response quadlet (old value) is the same as that one I
used as arg, to find out, whether the swap has been performed or not.

BTW: It is not important for me, but: Why are arg and data restricted to
be one quadlet, wheras 1394 allows lock operations for 32-bit and for
64-bit-values?

Manfred Weihs