Subject: [rohc] UDVM assembler and early interpreter for download

From: "Dr. Carsten Bormann" <[email-masked]>
Date: Thu, 7 Mar 2002 16:38:52 +0100

Sigcompers,

I have put a very early version of a UDVM implementation, together with a
(complete, I hope) UDVM assembler and some test programs and data at

http://www.dmn.tzi.org/ietf/rohc/udvm

The files are:

asm.pl    -- Assembler, outputs a hexdump.
udvm.pl   -- UDVM, takes a hexdump of code and a hexdump of input, very
noisy, incomplete
adam.udvm -- a test program, suitably hacked for sigcomp-05
test-in   -- that test program assembled, plus some test-data

How to use:

% asm.pl adam.udvm

Extract the hex dump (after the symbol table) and paste it before the test
data into test-in, then

% udvm.pl test-in

I'd love to get some feedback (and, of course, implementations for those
instructions I was too lazy to hack!).

I actually wrote this to test the spec, and I'm already unsure about the
definition of byte_copy_right in 7.3 (see comments in code).

Also, I expect that some of this will go into the UDVM user guide.

One comment about the test data: The program, of course, is not realistic
(it is big after assembly and also the scheme does not compress data very
well).
Still, it is from other sigcomp implementers, so there already is a shade of
interoperability (at least, until I hacked the program to fit -05).

Oh, and we may want to improve the assembly language a bit -- writing
DECOMPRESSION-FAILURE to get byte alignment is not quite it.
(The assembly language spec is informational, not normative.)

Gruesse, Carsten

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From: "Dr. Carsten Bormann" <[email-masked]>
Date: Fri, 15 Mar 2002 15:28:48 +0100

I have updated asm.pl and udvm.pl.
asm.pl now can do some arithmetic, which is needed for some more complex
cases, and has the align directive.
udvm.pl still starts at 6 (pending issue cabo-5), but now is good enough for
the deflate example (almost).

adam.udvm is the code, adam-in the resulting udvm.pl input for the simple
LZ77 example;
richard1.udvm and richard1-in similarly for deflate (unfortunately, it still
talks about the meaning of life, the universe, and b6vb26J-).

Enjoy.

Gruesse, Carsten

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of Dr.
> Carsten Bormann
> Sent: Thursday, March 07, 2002 16:39
> To: [email-masked]
> Subject: [rohc] UDVM assembler and early interpreter for download
>
>
> Sigcompers,
>

---

From: "Dr. Carsten Bormann" <[email-masked]>
Date: Sun, 17 Mar 2002 20:32:33 +0100

> I have updated asm.pl and udvm.pl.

I have updated udvm.pl again.
(I have not done Mark's newest revisionist syntax yet; a new asm.pl will
follow.)

I can now report that we have interoperability on simple LZ77, DEFLATE, and
a new LZW (the latter isn't on the web site yet).

Gruesse, Carsten