Transcode audit finished & bullet bug fixed!

Significant day today - finished the audit of the SUB ROM, and also fixed a long-standing bug!

I'm reasonably happy with the state of the transcode, though I may still need to tweak some of the execution flow to better accomodate the single-CPU architecture with respect to the VBLANK. I don't think it's an issue on the Neo Geo, but the graphics-intensive Amiga port may be another matter.

I've fixed the bug where some bullets just "hang" in the air. As happens way too often, you "fix" it and it still doesn't work - because it actually turns out to be a combination of multiple (in this case 2) bugs. In both cases, it was about register usage; one case of a register not being preserved around a subroutine, the other a case of a subroutine called from two places but parameters in different registers.

And only now that the bug is fixed, have I noticed that the Brag Zakato firing patterns look right!

Brag Zakato spraying 5 bullets

I also confirmed that one 'bug' was an artifact of skipping areas when debugging - it happens on the original version as well. In fact I don't really understand why it's happening, and suspect it's a bug. Regardless, it doesn't happen during normal gameplay.

That leaves me with three (3) outstanding bugs now; corrupt title screen after high score entry, extra Solvalou every hit, and a glitch that I noticed when debugging the graphics routine. The first is almost certainly a bug in the Neo Geo (OSD) layer, the 2nd may be related to dipswitch settings, and the 3rd I'm not even sure is a bug!

There is also the question of transparency in the Xevious sprites; jotd has pointed out that a whole bunch of sprite CLUTs have multiple transparent colour entries. I do know the crosshairs use such CLUTs, but was not aware of the others. I certainly haven't noticed anything "wrong" whilst testing... but I haven't been looking either. To be investigated...

Hopefully I can knock these off in the next few days and I can move onto sound!

I may also release a beta before adding sound for people to test the gameplay...