RE: break of close loop

["Dave Korn" <dave.korn@artimi.com>]

'Daniel Jacobowitz' wrote:
> On Fri, Nov 04, 2005 at 04:18:57PM +0100, Simon Richter wrote:
>> Hi,
>> 
>> Dave Korn wrote:
>> 
>>>  The stub is probably implemented by placing a temp breakpoint
>>> immediately after the instruction to be tested, but has negelected the
>>> fact that to handle jumps you may need to place the temp breakpoint
>>> somewhere _other_ than immediately after the instruction,
>> 
>> The question at hand appears to be breakpoints placed on top of the
>> instruction being stepped, as the instruction steps back to itself. This
>> is especially common on architectures with a dedicated "decrement and
>> jump if not zero" instruction.
> 
> If you have such instructions, and you don't have hardware single step,
> then you need to be prepared to either wait for the instruction to
> finish or else interrupt it.  I don't see the problem.

  No, I still think that's a buggy stub; I think that, given a djnz-style
instruction, "stepi" should execute it precisely once (decrement the counter,
keep PC the same if non-zero or advanced to next instruction if counter reg
now == 0), and "nexti" should run it to completion, shouldn't they?  That's
certainly how x86 debugging works natively.  The lack of hardware single-step
is something the stub should transparently handle.


    cheers,
      DaveK
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