Monday, 4 April 2016

CPC and fake joysticks

I couldn't resist starting to add support for CPC graphics. First task was to reorganise the memory map to cater for the 2BPP video display and buffer; it was a tight fit and for a few minutes I thought it wasn't going to work. But all good.

Ripping and adding the CPC sprite data was trivial. Adding support, however, won't be. The nature of the changes for the Coco3 are actually quite different to both the Amiga (planar bitmap memory) and the Neo Geo (hardware sprites pre-rendered in ROM). In addition, the panel sprites are quite different so there's a fair bit of work to do - likely too much to do before CocoFEST.

And so I returned to the issue of joystick - and directional - support. Since there was no code behind the main menu for input method selection, I added support for selecting Keyboard, Joystick and Directional Control, removing the other two ZX Spectrum-specific joystick options in the process.

The Main Menu is now tailored specifically for the Coco3 port

The ZX Spectrum uses flashing attributes to denote options selected in the menu - noticeably absent on the Coco3. Instead, I modified the text display routine to simply invert the character if the flash attribute was set, then added a blit to update the relevant lines on the menu each iteration through the main menu loop. Later I may invoke a timer and actually have it flash, but there's more important things to do first and CocoFEST is fast approaching.

Finally, I added a fake joystick read routine that - for now - simply reads an alternate set of keys from the keyboard. This will facilitate adding directional controls without complicating the issue with untried joystick code. I would expect that I'll have directional control working next session, which means all that remains is to replace the fake joystick read routine with the real one.

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