Subject:
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Re: Strange crash (and possible fix)
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Fri, 14 Jul 2000 18:25:41 GMT
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Viewed:
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1319 times
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Mike-
I wish I knew. I have frequently seen the same kinds of "random" changes
produce better results. For example, I had one piece of code that used a
switch statement- 19 statements in all. I added a 20th and poof... it
froze. I have no idea what could cause that kind of thing, but wish I knew...
Luis
On Fri, 14 Jul 2000, Michael J Ash wrote:
> Date: Fri, 14 Jul 2000 04:34:11 GMT
> From: Michael J Ash <mikeash@csd.uwm.edu>
> To: lugnet.robotics.rcx.legos@lugnet.com
> Subject: Strange crash (and possible fix)
>
> I had a strange experience today. My program likes to crash a lot. I
> accept this as a fact of life now; part of it is the difficulty in
> debugging it, and part seems to be the beta-ness of legOS. However, today,
> I tracked down one particularly evil bug, and I really don't understand it
> at all.
>
> Before, my program would crash roughly 50% of the time right at startup.
> I'd make some irrelevant changes and it'd be happy the next time.. maybe.
> Then I got the compiler working under LinuxPPC, and started playing around
> with LNP. I made some neat debug functions that let me see what was going
> on better. I tracked these semi-random crashes down to three lines of
> code.
>
> gNavInfo.x = 0;
> gNavInfo.y = 0;
> gNavInfo.dir = 0;
>
> gNavInfo was defined as:
>
> struct {
> long x, y;
> long dir;
> } gNavInfo;
>
> When the program did its weird random crashes, it was at those three
> lines. I'm certain of it. What I don't know is WHY? I changed the
> definition into a typedef and made gNavInfo a pointer to that struct. Then
> I use malloc to get a chunk for storage. Voila, my crashes seem to have
> gone away. The only thing I can think of is if something would break if
> the longs weren't aligned on a four-byte boundary. My "irrelevant" changes
> could possibly fix things so that they were on a boundary, on break things
> so that they weren't. But I don't see why that would crash. Does anybody
> have any insight?
>
> Btw, LNP is awesome!
>
> --
> "Do not go gentle into that good night.
> Rage, rage against the dying of the light."
> - Dylan Thomas
> Mike Ash - <http://www.mikeash.com/>, <mailto:mail@mikeash.com>
>
>
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Message has 1 Reply:
 | | Re: Strange crash (and possible fix)
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| (...) Well, it'd be nice to know, certainly, but I'm not going to look into it too hard. The fact is that it works wonderfully now. I compiled and downlaoded probably twenty versions of my program over the past two hours or so, and not a single one (...) (24 years ago, 14-Jul-00, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Strange crash (and possible fix)
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| I had a strange experience today. My program likes to crash a lot. I accept this as a fact of life now; part of it is the difficulty in debugging it, and part seems to be the beta-ness of legOS. However, today, I tracked down one particularly evil (...) (24 years ago, 14-Jul-00, to lugnet.robotics.rcx.legos)
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