Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!cs.dal.ca!aucs!880716a
From: 880716a@aucs.uucp (Dave Astels)
Newsgroups: comp.lang.c++
Subject: Re: calling Zortech C++ methods from assembly
Message-ID: <1990Aug20.121745.1815@aucs.uucp>
Date: 20 Aug 90 12:17:45 GMT
References: <1990Aug17.142520.5402@aucs.uucp> <1394@proto.COM>
Reply-To: 880716a@aucs.UUCP (Dave Astels)
Organization: School of Computer Science, Acadia Univ., Nova Scotia
Lines: 47

In article <1394@proto.COM> joe@proto.COM (Joe Huffman) writes:
>In article <1990Aug17.142520.5402@aucs.uucp>, 880716a@aucs.uucp 
>(Dave Astels) writes:
>>[...] invoke C++ methods from assembly.
>
>The reason it isn't documented is because it can be a real nightmare.

Most really powerfull things are.

>The names are mangled for type safe linking,

No problem.  I've read the sections on name mangling and it is simple enough.

>there are hidden parameters ('this') 

Again no problem.  Just an extra push or two.

>and virtual functions are really function pointers (that may change 
>their location between compiler versions).

This can be a problem.  However, if I need to invoke a virtual method, I can
have a non-virtual one to invoke which will take care of invoking the virtual
one.

>Basically, don't do it.  If you REALLY want to do it, call the function
>from a C++ function, compile with -gl (line numbers turned on), then 
>run OBJTOASM on the resultant .OBJ file.  This will generate the assembly
>code from the object code the compiler generated.  This will show you
>the mangled function name, how it's done with the current version of the 
>compiler and with that particular function.   

I had hoped not to have to resort to this again (this is how I taught myself
the C calling convention.

I've done this (asm->C++) successfully using Turbo Pascal 5.5, so the 
tricks (implicit parameter, etc) aren't new to me.  Borland outlines ALL
calling conventions fully in the TP5.5 manuals.  I do wish Zortech would
give full information in their manuals, for those of us who enjoy getting
our hands dirty.



-- 
"I liked him better before he died" - McCoy, ST V
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