Query about external format for lists (strings)

[Lawrie Brown]

Hi everyone

As part of my work developing the runtime for the EC Erlang Compiler,
I've recently been implementing its support for the external binary
format, based heavily on the low-level (en/decode*.c) erl_interface
code, but adapted to suit the rather different term coding we use. I
have a query about the list coding.  From my reading of the code, and
playing with binaries created on a standard erlang node, I take it that
a list is always terminated with the ER_NIL_EXT (106) tag. However the
code for encoding very large strings in encode_string.c as lists does
not seem to write this trailing marker.  Should it do so??? It confused
me at first since I based my overall list encoder on it, then wondered
why the binary from a conventional Erlang node for a list which I
decoded and then regenerated as a binary wasn't the same size as the
original, sigh.

Anyway, I'd appreciate any feedback:

1) confirming that ALL lists (incl those generated for very large strings)
   should always be terminated by ER_NIL_EXT;

2) and if so, whether the code in erl_interface*/src/en/decode_string.c
   is hence incorrect.

Thanks
Cheers
Lawrie


------------------------------------ <*> ------------------------------------
Post: Dr Lawrie Brown, Computer Science, UNSW@REDACTED, Canberra 2600 Australia
Phone: 02 6268 8816    Fax: 02 6268 8581    Web: http://www.adfa.edu.au/~lpb/