Re: lock operation

[Andreas B. <and...@mu...>]

On Sun, Mar 26, 2000 at 12:55:27AM +0100, Manfred Weihs wrote:
> 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.

Umm, yes.  I just forgot to return the reponse value somewhere (the
joys of cut&paste programming).  That's just libraw missing it, the
kernel side supports that (and will corrupt data in the user space
program or make it segfault if you still try to use the lock
function).

Will take care of that.
 
> 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?

I wanted to implement a separate lock64 function for that, I just
didn't get around to do that so far.

-- 
          Andreas E. Bombe <and...@mu...>
http://home.pages.de/~andreas.bombe/                DSA key 0x04880A44