Thursday, 3 August 2017

Closer to an Alpha Release!

Quick update; all of the IIGS code is pure 16-bit now except for two routines - the DVG CUR handler and the support routine that calculates SHR addresses and is only called from there. They need a complete overhaul and merging into one routine. On reflection there might just be enough savings to be had to be noticeable...

All of the rendering is done and optimised (including the small saucer and thrust) except for the exploding ship, plus I need to add data for 'dot' and 'underscore' characters for the high score entry & display. And that's it in terms of optimisation, unless I can coax more out of the hardware by using shadowing and/or blanking to my advantage. It's still around 18% faster from my crude calculations.

For an alpha release I'll rework the CUR routine, add the last pieces of the missing rendering, fix the object alignment, and add a crude text-mode splash screen. I'll tackle the flicker & sound after the alpha is out there.


UPDATE: The DVG CUR routine - and hence all IIGS-specific code in the main execution loop - is now 16-bit and optimised. I replaced the x160 calculation with a table look-up, whose instantiation was facilitated in no small part by CA65's .REPEAT command (nice!)

My latest crude calculation suggests it is ~28% faster with 4 large asteroids on the screen. After the alpha release I'll schedule rendering strictly to the arcade frame rate and see if it can keep up. Having said that, there's no guarantees that the arcade game maintains that frame rate either - there is leeway in the code to skip a frame or two before collapsing in a heap!

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