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<div class="moz-cite-prefix">Am 19.08.2013 06:00, schrieb Paul
Robinson:<br>
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<blockquote
cite="mid:1376884846.72229.YahooMailNeo@web162505.mail.bf1.yahoo.com"
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<div style="color:#000; background-color:#fff;
font-family:verdana, helvetica, sans-serif;font-size:12pt">I've
been busy, I have other things I had to attend to, then I
realized I couldn't figure out what was going on without a
decent cross reference program, but nothing that's out there
supports the UNIT construct, nor do they know how to skip over
{$DEFINE} {$IF} {$ELSE}, and so I stopped to write one and I was
busy with the work on that. I'm having trouble there, so I set
it aside. </div>
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I don't get what you're trying to say here.<br>
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<div style="color:#000; background-color:#fff;
font-family:verdana, helvetica, sans-serif;font-size:12pt">Anyway,
I came back and realized if I can get one of the Big Endian
ports working I can just figure out what files it uses and then
edit those to change the generated assembly language and/or the
object files if it makes object files the way the Pascal 8000
compiler for the 370 from the Australian Atomic Energy
Commission did back in the late 1970s and early 1980s did.<br>
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</blockquote>
Analyzing what a big-endian compiler generates won't help you there.
You need to look into the compiler's code and learn how it does
generate code for a specific platform. That has nothing to do with
big endian or little endian. <br>
<br>
In FPC there is the frontend which generates a sort of abstract
syntax tree on which then the platform specific backend generates
code. Thereby the backend provides platform specific nodes for that
abstract syntax tree of which then the "generate_code" method is
invoked. Platform independant stuff is normally located in the
ncg*.pas units and the platform specific stuff is in the nXY*.pas
unit of the corresponding CPU directory where XY is a short form of
the CPU, e.g. n68kadd.pas for the m68k add/compare node. Best is you
look how other CPUs are implemented (prefereably the simpler ones
like MIPS or m68k) and copy that more or less for the new platform.
<br>
<br>
Adding a new platform to FPC is not cheesecake and you should know
how the compiler's backend work. Just looking at the output of a
target won't help you!<br>
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<div style="color:#000; background-color:#fff;
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There are two things I'd like to find out to determine how it
might be possible to get Free Pascal ported to the s370 series.<br>
<br>
First, I want to add some of the compiler flags I mention in the
description of my attempts on the WIKI to add the s370 and/or
zSystem architecture, how do I get those flags - they do not
break the build - added as hooks to the compiler sources so that
eventually a {$DEFINE S370} statement can be added to get the
compiler to build itself for the 370 (and possibly other defines
depending on the machine and OS target}? There will eventually
need a new directory for the files that the 370 and whatever OSs
it uses supports, but, again, that's months away. I have to
start over, and I have to start somewhere.<br>
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</blockquote>
First step is to get a cross compiler to s370/zSystem working so
that simple programs can be compiled which you can use to implement
the RTL. Only when enough of the RTL is implemented and the code
generator works good enough then you can try to cross compile the
compiler, but not earlier.<br>
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<div style="color:#000; background-color:#fff;
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So how would I get the constants and values added to include the
s370 as a target for FPC? Would I submit them as a bug fix
request as a patch through bugs.freepascal.org on Mantis or
something else? I want to reserve a definition number for that
processor, at least for now so it has a fixed identifier so
eventually it can have its own PPU files and everything else in
the toolchain.<br>
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Search the compiler's source for e.g. m68k to see how other
platforms are implemented.<br>
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<div style="color:#000; background-color:#fff;
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Second, how do I create a cross-compiler that runs on Windows,
for any of the big-endian processors, so that I can see what it
has to generate code for the target machine? Given that, I can
change the code to either change the generated object file - if
it does direct object files - or the assembly language so it
generates S370 assembly.<br>
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No. You should learn how the compiler generates code and then
implement a new code generator backend for s370, maybe based on a
copy of another platform. Playing around with the output won't help
you.<br>
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<div style="color:#000; background-color:#fff;
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I can then run the compiler through itself to create a
cross-compiler assembly for the 370. Then I can recompile the
required modules, then take the assemblies, assemble them with a
370 assembler, producing an actual object module, then run the
program against itself and the compiler will at least compile
itself. Having done that, I can then create any necessary
changes to implement anything needed to provide the equivalent
functionality and rebuild the toolchain so it is native to the
s370 and units to provide localized services can be created as
needed.<br>
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First step consists of cross compiled hello world programs to
implement and test the RTL. The compiler is much too complicated to
get it running at first.<br>
<br>
Regards,<br>
Sven<br>
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