[fpc-devel] On a port of Free Pascal to the IBM 370

[Tomas Hajny]

On Wed, January 18, 2012 13:56, michael.vancanneyt at wisa.be wrote:
> On Wed, 18 Jan 2012, Tomas Hajny wrote:
>
>>> But then you are assuming the RTL should be using EBCDIC internally as
>>> well ?
>>> Obviously, that will be a lot more work.
>>>
>>> But I don't think this should be so.
>>
>> I may be overlooking something, of course. However: Our RTL is based on
>> common (target specific) routines for reading (and writing) text and
>> binary files (do_read & do_write). You cannot translate between ASCII
>> and
>> EBCDID in these target specific routines because you don't know how the
>> input would be used at that point (not even mentioning the fact that
>> there
>> is nothing like translation between ASCII and EBCDIC because there are
>> multiple different character sets for both and real conversion isn't
>> possible without taking this into account and knowing the real character
>> sets which again depends on the context which is again not known at this
>> low level).
>
> Once more: I do not think this is the task of the RTL. FPC and the RTL
> works
> with ASCII. That includes the expected contents of text files and whatnot.
>
> That a hypothetical FPC program opening an EBCDIC file on OS/370 needs to
> convert this to ASCII first is in my view the responsability of the
> programmer.
>
> The same goes for the FPC sources.
> I do not suppose that a FPC port would first convert the current ASCII
> sources to EBCDIC, but would continue to use the ASCII version.
>
> If you define the RTL as being able to handle EBCDIC on OS/370,
> it is a different matter, and a lot more work.

OK, could be, but not being able to work with text files created on that
platform without additional effort on the _programmer_ side (not the RTL
porter side because the RTL porter cannot address this easily within our
current RTL structure as pointed out above) would hinder usability of such
a compiler _a_lot_. It's certainly possible to start with that, but
keeping it that way in longer term would considerably decrease the value
of such undergoing in my opinion.

Tomas