Newsgroups: comp.sys.transputer
From: jan@neuroinformatik.ruhr-uni-bochum.de (Jan Vorbrueggen)
Subject: Re: Direct instructions vs. indirect functions
Organization: Institut fuer Neuroinformatik, Ruhr-Universitaet Bochum, Germany
Date: 06 Jun 94 11:26:45 GMT
Message-ID: <JAN.94Jun6122646@pallas.neuroinformatik.ruhr-uni-bochum.de>

In article <hone.24.000B634E@mlap.fb14.uni-paderborn.de>
hone@mlap.fb14.uni-paderborn.de (Uwe Honekamp) writes:

   The manual says that the process has been compiled to use direct
   instructions instead of indirect functions for channel i/o. The use of
   direct instructions would produce problems with the virtual links and
   interactive debugging.

   Hmm, how will the COMPILER know that a module is executed using virtual
   links or that a module will be debugged interactively?

Wrong way round. _You_ told the compiler, while compiling the offending
process, not to use the default of doing I/O via function hooks, but to
compile them into IN and OUT instructions. The latter is more efficient, but
prevents the debugger from taking control (by substituting the hook functions
with its own) on link I/O. But the debugger needs to use the same
communications network as your application in order to obey your commands :-),
so it has to have some way to synchronize operations on the links with your
application. Without the function hooks, it can't, and chaos will result for
interactive debugging. For post-mortem debugging, that's not a problem.

	Jan

