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Re: Memory corruption problem

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On 16 Nov in article <3414115857.Alan.Adams@ArmX6.adamshome.org.uk>,
   Alan Adams <alan@adamshome.org.uk> wrote:
> In message <575802fd6cNews03@avisoft.f9.co.uk>
>           Martin <News03@avisoft.f9.co.uk> wrote:
> > On 16 Nov in article <dd0dec5757.Alan.Adams@ArmX6.adamshome.org.uk>,
> >    Alan Adams <alan@adamshome.org.uk> wrote:

[Snip]

> > If there are a multiplicity of writes that cannot be verified, can
> > you add a guard word at the end of each block, and check they are
> > valid as often as possible?

> I'm doing that for the ring buffers, to guard against overruns.
> However I don't think this is an overrun, more likely a
> miscalculated pointer, which could be absolutely anywhere in the
> address space.

All I can suggest is to write a simple PROC to validate a pointer as
between TOP and HIMEM. Then add calls before your most likely pointer
writes, until you have either done them all or found a culprit. 
Tedious, unless anyone can think of a better way!

> It would be nice to have proper memory protection - I grew up with
> VMS which would produce "access violation" when this happened, and
> a stack dump to show you how you got to it. Unfortunately putting
> reportstack in the error handler is useless, because the call
> stack has already gone.

It is one of the limitations of RISC OS, and BASIC in particular.
I was used to MVS protection and debugging facilities!

> I've upgraded to 5.25, which made no difference. I don't think it's 
> high-vector though - how can I tell?

!ScrHelp from Chris Hall will tell you ... and there are probably
other ways as well.

Martin

-- 
Martin Avison 
Note that unfortunately this email address will become invalid
without notice if (when) any spam is received. 

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Thread

Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-16 13:15 +0000
  Re: Memory corruption problem Martin <News03@avisoft.f9.co.uk> - 2018-11-16 15:21 +0000
    Re: Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-16 15:53 +0000
      Re: Memory corruption problem Martin <News03@avisoft.f9.co.uk> - 2018-11-16 20:04 +0000
        Re: Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-16 22:38 +0000
          Re: Memory corruption problem Martin <News03@avisoft.f9.co.uk> - 2018-11-16 23:46 +0000
  Re: Memory corruption problem David Buck <dbuckhome@gmail.com> - 2018-11-16 23:15 -0800
    Re: Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-17 12:21 +0000
      Re: Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-17 13:10 +0000
        Re: Memory corruption problem Martin <News03@avisoft.f9.co.uk> - 2018-11-17 19:01 +0000
          Re: Memory corruption problem Alan Adams <alan@adamshome.org.uk> - 2018-11-17 21:04 +0000
        Re: Memory corruption problem Erik G <noreply123@xs4all.nl> - 2018-11-24 20:17 +0100
    Re: Memory corruption problem "John Williams (News)" <UCEbin@tiscali.co.uk> - 2018-11-17 12:26 +0000
    Re: Memory corruption problem David Higton <dave@davehigton.me.uk> - 2018-11-17 20:59 +0000

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