Manage 2P in attract and game example

[totologic]

Hi.

Back to the attract-and-game example, I try to adapt it in order to manage properly 2 players.

The kind of scenario I want to support is the "here comes a new challenger", in the same way Puzzle De Pon does: when one player is already playing and the other is pushing START, a credit is DOWN and the game is interrupted to start a new 2P game.

The problem I meet is the impossibility to have the inactive player to spend a credit by pushing START while the other is already playing. I tried to set up all kind of registers (BIOS_USER_MODE, BIOS_CREDIT_DEC, BIOS_PLAYER_MOD1...) with different values, but nothing work as expected. I always have both player able to spend a credit (which is a fault for the player already playing) or none of them.

[dciabrin]

Good question, I'll try to come up with something if you don't beat me to it.

(Also for good measure I might need to tweak the nullbios substitute ROM to support 2 players credit management...)

[totologic]

I found a discussion from 2015 illustrating and solving the exact same problem.

https://www.yaronet.com/topics/171604-user-subroutine-with-neobitz-c-dev-kit-datlib

Im not sure I can solve it myself with my skills as the solution involves modifications in the ASM header. But I am going to give a try.

[dciabrin]

I just added a new example 10-credits-management in branch https://github.com/dciabrin/ngdevkit-examples/tree/credits, it requires a fairly recent ngdevkit as it uses bios variables defined in the latest ld linkscripts.
Could you check whether it does what you wanted?

Note: it doesn't work with nullbios yet, as I need to implement the small bits required for credit management with multiple players. Once done, I'll merge this new example into the main branch.

[totologic]

I tried so many things, except to write directly in the bios_start_flag :'(

Your example is perfect, exactly what is expected in a game.