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Subject: Re: Using DJGPP for C++ DOS development today?
From: John Davidson <codewhakker AT gmail DOT com>
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Hans-Bernhard Bröker wrote:
> The library in question would be the C++ runtime library, a.k.a. libstdc++

Sorry if I'm just misunderstanding something (I don't know anything about compilers beyond a basic grasp and never had to rebuild anything), but can't I just rebuild libstdc++ from source for the 386? Is it full of inline assembler?

I found this:
https://groups.google.com/forum/#!topic/comp.os.msdos.djgpp/WeMjxnR1NBc
which seems to indicate that GCC will output non-386 opcodes anyway :-(

http://gcc.gnu.org/onlinedocs/libstdc++/faq.html says:
"Only when actually running the code on a i386 will the problem appear.
This is fixed in 3.2.2."


Rod Pemberton wrote:
> An alternate solution might be instruction emulation.

Thanks, didn't think about that! It sounds like a fragile solution though; wouldn't there be problems with switching in and out of protected mode? (man, I never thought I'd ever say that again!)

Surely something as basic as the xadd or cmpxchg instruction must be used by every other function if it was enabled during compilation, so opcode emulation would be a big performance hit?

Or do I just write the 486 emulation myself in DJGPP? I can't remember all this DOS interrupt business. I guess I'll have some catching up to do. And stocking up, on aspirin...