All Geekness Great and Small

Archive for the ‘perl’ Category

I’m currently working on some Perl that processes memory dumps from a hardware appliance.

Frequently, within these dumps, I’m face with a buffer that wraps. That is to say, each entry in the buffer is filled and, once the buffer is full, the next entry to be filled is the first, again (overwriting the old value).

At the point in time that the dump is taken, there is an index value that points to the ‘start’ of this buffer (i.e. the point in the buffer that is the oldest). Unfortunately, when Perl gets hold of the buffer, it represents it as an array, with the first entry in the array being the buffer entry with the lowest memory address.

So… given an array representing a buffer and an index to the logical start of the buffer, what’s the simplest way to rejig it, so that the array represents the logical order of the buffer instead of the physical order?

Voila:

splice @buffer, 0, 0, (splice @buffer, $start_index);

I’ve been coding in Perl for years and, generally, I think I’m a pretty competent coder. However, every now and again, I fall into a hole that takes me a loooong time to get out of. Invariably, these problems boil down to upload issues, not code issues. As an aide-mémoire for myself and, hopefully, to you, I thought I’d jot down a few problems that I’ve seen and what the solution was.
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