[fpc-pascal] SinclairQL (M68K) Port

[Norman Dunbar]

Morning Charlie,

On 21/03/2021 09:23, Karoly Balogh via fpc-pascal wrote:
> ...It was on my ToDo to get back to it, but actually, I
> prefer indeed if the QL community sends patches... 
  Ok, no worries. I can "svn diff" if that's what you would prefer? 
Where should I send them, when I'm ready please?


> I was just not going to
> the QL forum lately, there's always one too many retro platforms to care
> for. :| Sorry about it!
No problem.


> What are you trying to do here? This isn't valid Pascal file handling
> code. ....

Yes, I know. Sorry, I could have explained better. This is the file I 
was testing:

{ Program to demonstrate the Erase function. }

Var F : Text;

begin
   Assign(F,'ram1_test.txt');
   Rewrite(F);
   Writeln('The file, "ram1_test.txt" will be deleted.');
   Writeln(F,'Try and find this when I''m finished !');
   Close(F);
   Erase(F);
end.

In the end, the only way I could get it to actually delete the test 
file, on device ram1_, was:

Var F : Text;

begin
   Assign(F,'ram1_test.txt');
   Writeln('The file, "ram1_test.txt" will be deleted.');
   Erase(F);
end.


> The RTL on init will open stdin/stdout for you on start, so simple I/O
> works on the console, so your writeln() will succeed, regardless of you
> trying to reopen the console afterwards.

Hmm. I wasn't trying to reopen the console, the line in the test program 
that barfed was this one:

   Writeln(F,'Try and find this when I''m finished !');

I have a minimum test harness for it at the moment that I'm attempting 
to sort out.

Var F : Text;

begin
   Assign(F,'ram1_test.txt');
   Rewrite(F);
   Writeln(F,'Try and find this when I''m finished !');
   Close(F);
end.

I've tested with just the assign and rewrite, seems to have had no 
effect - the output file, which has some text in it, remained untouched. 
Adding in the writeln call causes runtime error 103. Which I believe is 
"file not open".

> Write()/Writeln() and WriteStr() are special functions, which the compiler
> handles directly, and breaks them down into a series of individual calls,
> depending on the type of the parameters in the parameter list printed.

Understood, thanks.

> you probably don't need to touch that code anyway, as everything just
> calls do_write() in the end, which is in rtl/sinclairql/sysfile.inc.

Thanks, that's where I'll start looking for problems.


> If you know m68k assembly, You can easily identify which functions are
> called directly, if you generate assembly code with the -al parameter,
> while compiling.

Excellent, I'm reasonably au-fait with M68K assembly. (Famous last words!)

> Then you can check directly what the compiler does with
> your code, and which functions it calls (even if name mangling obscures
> them a bit, but it's still possible to understand better what is going on
> then). But as I said, you won't need to touch any of these.
> 
> The Reset() function's implementation is in rtl/inc/file.inc, along with
> Rewrite(). But you most likely don't have to touch these either, because
> they internally wrap to do_open(), which is in rtl/sinclairql/sysfile.inc.

Ok, I'll have a look at those as well, just in case.

> This might need to be extended to handle various file open modes (read,
> write, overwrite, append, etc) better. Also, integrating console handling
> in there might have its own quirks.

Probably not. The QL treats the console as a text file and pretty much 
anything goes, tabs, positioning etc.

> ... This code is in rtl/inc/. And it wraps to system-specific
> functions internally, which are already in the sinclairql RTL, just mostly
> weren't implemented. Basically any do_<something>() functions which you
> see in there.

Aha! Just what I was looking for. I knew this stuff had to be system 
specific.

> ...


Many thanks indeed, I'll see what I can come up with.


Cheers,
Norm.

-- 
Norman Dunbar
Dunbar IT Consultants Ltd

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