This project is dedicated to the memory of William Morris (aka Frags), who was the main contributor to the bounty but was unable to see the final result.

Sunday, August 18, 2013

Moving stuff around

Long time no see! No wonder: we just moved to a new house, which usually means lots of things to deal with and boxes wherever I look. (I hate this soo much! I badly need my daily routine, but how can I find my stuff?!) Finally, we are getting settled again and I was able to dig up the good ol' Amiga again under the pile of boxes. And this new house is just awesome, so it worth all the pain we went through.

Interesting coincidence, but right before we started the whole move house craziness (seems like ages ago, BTW) I decided to refactor some code in E-UAE JIT. Namely the handling of the temporary registers.
It was such a bad design, or rather no design at all: I used the number of the allocated temporary registers to index a couple arrays with the relevant data in it. Can you believe this? In 2013? This was unacceptable even in the '70s. There are so many reasons why you shouldn't do that.
Also what is the point of using a strongly typed language, if we don't use distinct types? In this case all the temporary registers along with the actually mapped PowerPC processor registers are passed to the functions as integers. Very easy to misuse. Bad, bad, bad.

In the recent changes I have managed to introduce the concept of a temporary register-specific type structure, which is also able to carry around the mapped PowerPC processor register number and the register dependency map for the macroblocks.

This new structure can be used when the macroblocks are collected (so mostly in the helper functions), but the code emitters for the macroblocks are dealing with the mapped PowerPC registers only. Now, I still need to solve that one: at the moment these are still passed to the functions as integers.

And what is the visible output for you guys? Nothing, if we are lucky. ;)
Yea, I know. It is always hard to justify the time to the business owners what was spent on solving technical debts. But this was a long outstanding one and I always had the itch of fixing it.

So, enjoy your Summer while it lasts and bear with me.

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