Right now I'm just spec-ing the project and have a few days to muck about - we have an end goal and my boss wants an order of magnitude estimate for planning. It doesn't have to be a general processor, and some exploration of the way this source code is constructed has suggested that an easier solution is manual translation of the (evolving) code base which I will codify into a script.

If all your if blocks have to next to avoid entering the continue anyway

I don't know if you're following my program flow - the nexts don't skip the continue block, they're effectively gotos for the continue block. I personally prefer an if(){next} to if(){}elsif structure - to me it reads easier at the expense of a keystroke (wholly subjective) - but that is irrelevant to the overall while-continue structure. By using a continue, it means unless I hit a line where I explicitly say I've successfully parsed (undef $_, next;) the error code is executed.