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UI21DEB deBUGGER released | crappy and incrappy stuff (Announce)

posted by ecm Homepage E-mail, Düsseldorf, Germany, 15.03.2009, 21:02

> > "Will your TSR allow the debugger to single step into Int 21 without
> > causing a mess?" was kind of a trick question.
>
> I see. :surprised: The optimal case of a post of yours is a tricky
> question, the other, also pretty frequent case, are just rude attacks
> without any relation to original topic :crying:
This isn't true, just as it won't be true to say all your posts are crap and some more crying.

> Cm wrote:
>
> > I probably won't ever use some program by DOS386
> > but I still prefer acceptable useless programs over crappy ones
>
> Interesting point. :-) The fear or virii pushes people into the
> irrationality, when the irrationality is exhausted they move on into the
> absurdity, and when the absurdity is exhausted then ... :lol3:
Do you plan on writing any virus soon? To fear the mass of DOS users or so?

> > It just calls Int21 between all instructions
>
> Excellent (RTFS) :clap:
If you prefer NASM source, mail me.

> > (you could avoid this by setting my own DEBUG fork's [NDebug's]
> > "assume InDOS" mode, but it's DEBUG's right to do that anyway)
>
> I'm not that sure about that.
Well it still is, especially in case of Int21.50 and Int21.51 which are reentrant in M[es]S-DOS. For Int21 character I/O, see below.

> In JDEBUG source I see 3 branches:
>
> * INT $21 console
> * BIOS console
> * INT $21 redirected
>
> And I'm very skeptical about both the INT $21 console: dropped in favor of
> BIOS if debugging DOS kernel ... but why not always ? :confused:
Well, because apparantly Japheth never used DEBUG's help command '?' when tracing DOS. I'm currently looking for more occurances of Int21 that have to be avoided during InDOS mode. (L's and W's DOS calls are obvious cases here. I'll add "Can't do this while InDOS" messages for these.)

> and the
> INT $21 redirect ... seems obsolete, no need to abuse DEBUG as an
> assembler anymore (maybe things were very different 20 years ago, heh
> :lol:).
I don't know what exactly you mean by "Int21 console". If you mean functions 01h-0Ch, these are redirected through the PHT (RBIL JFT) too as mentioned in RBIL61.

> > Your reentrancy counter (vvreecnt) would be sufficient if the code
> really used
> > it (despite the machine halting [?] when it reaches 255).
>
> Any better ideas ? Set up a 256-bit counter providing a "sufficiently low"
> probability of overflow before the universe implodes ?
What about a 1-bit NUL counter which is never increased? That's probably as useful as your previous solution ;-)

> > Of course MS-DOS's usage of InDOS is not sufficient.
>
> Interesting.
Just as interesting as all the other bad crap (there's some good crap too..) Microsoft did. More interesting might be whether (E)DR-DOS and DOS-C duplicate this uncomfortable behaviour.

---
l

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