Debugging oddity

A slightly odd thing: I’m working on a fairly complex bit of BASIC code, and reached a point where a certain action froze the machine into an endless hourglass loop, escapable with Alt-Break. I added a VDU 4:PRINT "Got here" statement ahead of where I thought the problem might be, just to check things were working up to a certain point, and this time everything worked as intended – I was able to perform as many actions as I liked without triggering the bug.

Now I’ll have to look through the code more carefully to see where things are breaking down, but does this surprising (to me) behaviour offer any clues as to what the problem might be? Ie, does printing a character reset anything that I might have corrupted somehow?

Now if this was a C program, I’d say you were overshooting an array and trashing something important (local arrays are on the stack, so mucking up can have obviously naff effects).

So… are you doing anything freaky with memory access? this%?that% sort of stuff? Maybe something similar?

are you doing anything freaky with memory access?

It’s Maestro, so the entire thing is something freaky with memory access ;-)

Yeah, that’s what I assume is going on. There’s an awful lot of indirection operators – setting and unsetting bits within blocks of bytes – so I assume I’m running off the end of some allocated space somewhere.

I assume I’m running off the end of some allocated space somewhere.

Have you looked at *ReportMem V provided by Reporter? It validates and checks over 120 lists within BASIC (quickly) and identifies many cases of overrunning space.

Have you looked at *ReportMem V provided by Reporter?

No – thanks. I’ll take a look at that and see if it can help out.