On 3/27/2023 2:45 AM, Jacob Kroon via fpc-pascal wrote:
Hi,
I have some old Pascal code that was compiled in a CPM environment
using the Pascal/MT+ compiler from Digital Research. I'm trying to get
this project to build in a modern environment, for a start using
FreePascal.
First, is anyone aware of a tool for converting this dialect of Pascal
to something that FreePascal will accept ?
Well, it is a very long time since I used Pascal MT+ the last time, and
that was already on the x86 version (+30 years now), but the same things
should still apply.
First of all, Pascal MT+ is more or less ISO7185 compatible, so you
would have to use that mode in FPC if you don't want to change all those
file reference (that's what's mostly different to a "real" Pascal :P )
As for the "external" vars (and possibly procedures/functions), it is
not quite the same as the units in UCSD/Turbo/Delphi/FreePascal, but it
had the possibility (due to source code size restrictions, you had only
64KB for OS, compiler and source code together) to compile different
source files into separate object files, which then could be linked
together with the linker. It is more of an "forward" declaration. In
most cases, I would assume that you could actually copy all those source
files that are being referenced into a single source file. Using units
could work in a lot of cases, but which way to go might depend on your
actual use case...
Ralf
Second, the old code contains a lot of:
var
foobar : external integer;
in sources that reference 'foobar', then there is a declaration in one
of them:
var
foobar : integer;
As I understand it, in order to translate this to something that
FreePascal understands, the variable needs to go in a "unit" and be
part of its interface. Then, pascal sources that needs to reference
the variable should use this unit. Is this the easiest way forward ?
I thought maybe I instead could adapt the syntax like:
var
foobar : integer; external;
but with this I still get undefined references when linking. Using
units seems ok.
Bets regards
Jacob
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