[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

gas: additional macro functionality (patch attached)

From: Olaf Püschel
Subject: gas: additional macro functionality (patch attached)
Date: Mon, 13 Aug 2007 16:49:46 +0200


When I was trying to implement a direct threaded code interpreter (forth look alike) with gas for the msp430 microcontroller, I missed the possibility to reference a) the individual invocation count of each macro and b) the previous invocation
count for each macro.

Problem: I need to build a single linked list at assemble time. This is traditionally
done with somethink like:

                .set LINK, 0

.macro  HEAD foo, bar
                .word   LINK
                .set            LINK,.

This does not work with gas assembling msp430 code on a PPC Mac, because
LINK only gets resoved at relocation time, so all LINK fields are the same :-(

The presence of the \@ ideom hinted to me, that I could easily tweak gas to yield
the information I need. So I made two changes::

1) "macro_entry" gets another field "count", giving the individual invocation count 2) The ideoms \#, \< and \> yield the current, previous amd next invocation count
    when used in a macro.

So I can write the linked list code like:

.macro          HEAD len,name,link,flags=0
lnk\#:          .byte   (\flags << 5) | \len
nam\@:          .ascii  "\name"
                        .org    nam\@ + 3                       ; pad short 
                        .word   lnk\<

Tested, works :-)

I would love to see my code incorporated in the next gas release, since I consider it useful not only to me. If you need to have some documentation writen to do this,
i'll be happy to provide it.

Attached are the diff's for macro.h and macro.c

Best regards

/~\ The ASCII       | Olaf P?schel, OLMOS Technologies GmbH, Germany
\ / Ribbon Campaign | Senefelderstra?e 11, 38124 Braunschweig
  X  Against HTML    | Phone: +49-531-22020-0 Fax: +49-531-22020-99
/ \ Email!          | OLMOS supports signed and/or encrypted mail.

Attachment: gas-2.17_macro.c.diff
Description: Binary data

Attachment: gas-2.17_macro.h.diff
Description: Binary data

reply via email to

[Prev in Thread] Current Thread [Next in Thread]