This is a preliminary announcement regarding the rewrite/revamp of the NASM preprocessor.

This rewrite addresses issues with implementing recursive macros (%rmacro/%irmacro) as previously attempted, %exitmacro and also makes room for new directives.

New NASM Directives:

  • %rmacro: Recursive Macro, can be called arbitrarily deep (really high limit [2^20] set to catch infinite loops.)

  • %irmacro: Same as above, except case-insensitive like %imacro.

  • %exitmacro: Terminates the current macro invocation, much like %exitrep; can be nested in other preprocessor directives (e.g. %if/%endif) within the macro, with exception of another macro, of course.

  • %while/%endwhile/%exitwhile: A fusion between %rep and %if.

  • %comment/%endcomment: Comment block for long/multi-line comments. A little syntactic sugar, if you will.

  • %final: Causes rest of line after %final to be preprocessed after all other "normal" preprocessing is complete. Multiple %final directives work like the x86 stack, LIFO/FILO.

This rewrite also attempts to address heavy/nested macro invocation efficiency issues.

This rewrite is currently a branch [in GIT] called preprocessor-rewrite, and tentatively labeled as version 2.10rc1. Please note that NASM 2.09rc (official/main/master) is still going and NASM 2.09 should be released fairly soon.

This rewrite has been known to accurately build all NASMX demos, along with a variety of other code snippets by various people.

As positive/successful as this rewrite has been thus far, it is still a major change and we would like to catch as many bugs as possible before merging it into the main/master NASM code base.

Please help us test this rewrite further by downloading/compiling the preprocessor-rewrite branch of the NASM source code, and testing it against your NASM code/snippets.

Windows (Win32/MinGW) Binaries: (these binaries will be updated when new preproc-rewrite updates are made, along with a corresponding reply to this thread.)

Source Download via Browser: goto and click on the top-most tar.gz or zip "snapshot" link, decompress/unarchive accordingly.

Source Download via GIT:

git clone git:// preproc-rewrite
cd ./preproc-rewrite
git checkout origin/preproc-rewrite

Compiling on MacOSX/FreeBSD/Linux/et al.: (assumes you are in the preproc-rewrite directory of the downloaded source)


Shell Script for GIT Download + Compiling on MacOSX/FreeBSD/Linux/etc al.:

git clone git:// preproc-rewrite
cd ./preproc-rewrite
git checkout origin/preproc-rewrite

If you are comfortable enough with making this branch of NASM your primary binary on MacOSX/FreeBSD/Linux/et al., follow the above compile instructions with: sudo make install

If there are any questions/comments/corrections/concerns, please reply to this thread.

Thanks. -SpooK
Posted on 2010-08-06 00:36:25 by SpooK
MASM has a recursion depth limit somewhere around 20 deep, saying I am interested is a gross understatement.
With recursive macros, and nested structure definitions, NASM is finally ready for a full-blown object oriented buildtime assembly environment.
Just wondering why recursive macros need a different directive to single-depth ones.
Posted on 2010-08-06 01:31:47 by Homer

Just wondering why recursive macros need a different directive to single-depth ones.

I can think of two immediate reasons.

1.) So macros (syntax and all) doesn't break existing code because...
2.) Macros can be used to overload instructions, a situation where you would want recursion, e.g (a simplistic example)

%imacro call 1

#2 is (was?) fundamental to NASMX and a few other projects.
Posted on 2010-08-06 01:57:23 by SpooK
wraps them both under the mantle of a common directive which sets a per-macro-name buildtime switch that triggers nested macro references to use the new macro directive
Posted on 2010-08-06 02:34:29 by Homer
Update: Fixed a bug regarding the emission of labels that immediately precede macro invocations. The new source/binaries are available, and can be found as instructed in the initial post.

Note: The latest x264 source successfully builds and passes checkasm with this preprocessor rewrite of NASM.
Posted on 2010-08-06 07:02:12 by SpooK
Update: Fixed line number handling.
Posted on 2010-08-09 01:30:27 by SpooK
Update: Fixed macro-relative line number handling for %warning/%error/%fatal/etc. This update, combined with the general preprocessor redesign, now allows for %warning/%error/%fatal lines within %rep blocks, that are nested within macros, to correctly emit the exact macro-relative line number.

Update: Context-local labels will no longer implicitly search upper/outer contexts in the case of undefined labels. This feature was added in NASM 0.98.03, and is now being removed due to its unintuitive and error-prone design. There will be a deprecation warning for "usage" of this feature in the NASM 2.09. For NASM 2.10 and beyond, relying on this context-local label fallthrough will simply generate an expression syntax error. If you rely on this soon-to-be deprecated feature, please take this time to adjust your code, accordingly.

Note: The Win32 Binaries link has changed:
Posted on 2010-08-09 23:39:26 by SpooK