Choosing and Using an Assembler

Avoid K-Seka!

Problems with Devpac?

Problems with ArgAsm?

Assembling within Cygnus Ed

Don't use the K-Seka assembler!

Is it any coincidence that almost every piece of really bad code I see is written with Seka? No, I don't think so :-)

When buying an assembler check the following:

1. That it handles standard CBM style include files without alteration.

2. That it allows multiple sections

3. That it can create both executable and linkable code

4. 68020+ support (especially if you want to program for A1200, writing A1200 code without 68020 instructions is real stupid!)

Devpac 3.0 is probably the best all-round assembler at the moment. People on a tighter budget could do worse than look at the public domain A68K (It's much better than Seka!). I'd suggest using Cygnus Ed as your Text Editor, or Turbo Text.

Devpac optimise mode produces crap code?

If you're using Devpac 2.x and have found that the OPT o+ flag produces crap code, then you need to add the option o3-. This is indeed fixed in >=V3.02

Under certain circumstances the optimiser will optimise relocate references in the first 64Kb of your code to word addressing, which obviously isn't very good if AmigaDOS then loads your code above 65535, which is quite likely!

o3- disables short-word address optimising.

This isn't necessary if you're creating linkable code (with l+), and indeed may be fixed in current versions of Devpac 3

My current option setup for Devpac is:

   opt   l+,o+,ow+,ow1-,ow2-,ow6-,d+,CHKIMM

l+ sets linkable code on (as I mix C and Assember in my current projects)

o+ enables optimise mode.

ow+ enables optimiser warnings (they act as errors with SLINK, so I edit
my source when I get an optimiser warning)

ow1- disables warnings on short backwards branch optimising

ow2- disables warnings on address register indirect with displacement zero
to address register indirect optimising, again I don't want to edit my code
if I have (for example)

         move.l   vs_vscreen1b(a0),a1  ; vs_vscreen1b = 0

ow6- disables warnings if short branches forwards can be made

d+ debug information on

CHKIMM - Check Immediate values. This will report an error if any
immediate addresses are used (the most common mistake in assembler
is to leave the # from a value). Address 4 (EXECBASE) is allowed, and
other fixed addesses (eg CUSTOM - $dff000) are allowed as long as
you add a .L to the end.

         add.l 123,d0         ; This now gives an error!
         LEA   (CUSTOM).L,a0  ; This doesn't.

Argasm produces crap code, whatever happens

First, Argasm (unlike Devpac) from the Command Line or if called from Arexx using Cygnus Ed (my prefered system) defaults to writing linkable code, so if you want executable files you need to add

        opt l-    (disable linkable code)

If you find that your Argasm executables fail then check you haven't got any BSR's across sections! Argasm seems to allow this, but of course the code doesn't work. Jez 'Polygon' San from Argonaut software who published ArgAsm says it's not a bug, but a feature of the linker...

Yeah right Jez...

But Argasm is *fast*, and it produces non-working code *faster* than any other assembler :-)

Argonaut have abandoned ArgAsm so the last version (1.09d) is the last. There will be no more, and it doesn't support 68020+ instructions, so I've stopped using it now.

Using Arexx with Cygnus Ed

Cygnus Ed is a wonderful system: Included in the the utils/ced directory are a few macros I wrote that may help you configure your assembler to run in CED.

To install:

1. Make sure Rexxmast is running and you have copied the macros to your REXX: directory (make a sys:rexx directory rather than assigning REXX: to S:)

2. Add the line

ced -r

to your s:user-startup. Copy the CygnusEd Activator (on Cygnus Ed V2.1x distribution disk) as C:ed, yes, that's right. Right over the top of the abysmal Commodore editor!! You lose 200Kb of fastram doing this, but believe me, it's worth it. Whenever you need to use Cygnus Ed, either type ed filename and it loads in a flash, or just press Right-ALT/Right-Shift/Return to open a new CED session.

The CygnusEd Activator is public domain, and is in the utils directory of this archive.

3. Install the commands on the keys you want to use (under the special menu).

I currently have mine set up:

F1  - devpac.ced      - This calls Devpac to assemble the current file.
                        Output is file ram:test, errors to ram:errors

F2  - argasm.ced      - Same, but for Argasm


F3  - errors.ced      - Open and close the error window. The error
                        window is not editable.

F10 - ram:Test        - Execute the code!

Other keys are free for C, TeX or whatever else you want to use...

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