[Coco] Fooling around with assembly in RS-DOS environment

[Dave Philipsen]

Lee, here's a little code snippet that I use a lot for displaying text 
strings.  In fact, I have it as 'ROM call' in a monitor I use quite a 
bit.  If you're displaying text strings with standard ASCII 7-bit 
characters you don't even have to use a null terminator.  Just set bit 7 
of the final character.  It makes it a little easier so you don't have 
to set aside a separate data area for your string. You can add your own 
modifications to this code by creating other entry points for 
positioning the cursor before you display the string or perhaps changing 
fg or bg colors.  Also, you may or may not want to preserve the X 
register or clear the A register on return:


         org    $3f00
start   jsr    text
         fcs    "HELLO WORLD!",$0d
         rts



text    pshs   x        save x register
         ldx    2,s      get pointer to string (pc)
txt1    lda    ,x+      get a character
         bmi    txt2     if hi bit is set, it's the end of the string
         beq    txt3     if zero, it's null-terminated
         jsr    [$a002]  ROM call to display character
         bra    txt1     get next character
txt2    anda   #$7f     mask off hi-bit
         jsr    [$a002]  display character
txt3    clra
         stx    2,s      return address (pc) just after end of string
         puls   x,pc     return from subroutine to modified address



Dave




On 4/10/2016 11:31 PM, Lee Patterson wrote:
> Mark,
> I was looking at the ASXXXX assembler, to be able to write assembly for my PC-1360 Pocket Computer. Would be good to use for both 6809 and 1360. Could I trouble you for a sample command line to compile a 6809 asm to a DECB binary using the AS compiler? Maybe a tiny hello world asm to go along with it if it is different then mine?
>
> I did this one for lwasm:
>
> # lwasm -9 -b -o hello1.bin hello1.asm && writecocofile --verbose hello.dsk hello1.bin && coco3 `pwd`/hello.dsk hello1
>              org     $3F00
> start       ldx     #msg        point to our message
> lee         lda     ,x+         get current ASCII character
>              beq     x@          exit if it's the NULL-terminator
>              jsr     [40962]     print the character using stdout hook
>              bra     lee         keep printing
> x@          rts
>
> msg         fcc     "HELLO WORLD!"
>              fcb     13,0
>
>              end     start
>
>
>
> Thanks,
> Lee
>
>
>> On Apr 10, 2016, at 11:40 PM, Mark McDougall <msmcdoug at iinet.net.au> wrote:
>>
>> On 11/04/2016 10:21 AM, Rich Carreiro wrote:
>>
>>> I'm not a purist on this -- it does NOT have to be EDTASM
>>> running on the emulated CoCo (in fact, I'd probably prefer
>>> it wasn't, since I don't feel like dealing with 32-char line
>>> lengths and all-caps when programming).
>>>
>>> Are there any CoCo assemblers that can run in Windows
>>> or Linux that can create executables that a CoCo emulator
>>> can load and run?
>> At the end of the day, I prefer productivity over the "pure" experience of developing on the Coco, so for me cross-assembling is a no-brainer.
>>
>> Personally, I use AS6809 which will produce a Coco .BIN file courtesy of contributions by our own Boisy Pitre. I use my favourite editor (70 lines of text) and it's all command-line driven so a makefile does all the building.
>>
>> For testing/debugging I use MESS which, despite claims I don't understand, is far more powerful than any other Coco-based debugger could ever hope to be (eg. watchpoints), and gives you more information to boot. I've used it for both reverse-engineering and developing software on all sorts of platforms, not just Coco. It's invaluable in my arsenal.
>>
>> In my personal opinion, integrated IDE's that supposedly make your life easier are of very limited benefit to a seasoned developer, regardless of platform. Pressing <UP><UP><ENTER> twice, once to build and once to run MESS is not exactly taxing, and ultimately more flexible and customisable.
>>
>> It's doubly true in my case, because I develop for multiple retro platforms, and use the ASXXXX assemblers for all of them. My entire development environment is identical then for each of them, which is a definite productivity boost.
>>
>> I'm sure plenty disagree, and you may even be one of them.
>>
>> Regards,
>>
>> -- 
>> |              Mark McDougall              | "Electrical Engineers do it
>> |  <http://members.iinet.net.au/~msmcdoug> |   with less resistance!"
>>
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>