Proposed fix for the behaviour of STP

[NollKollTroll]

I have 2 setups, one using a real WDC65C02 connected to a Teensy 4.1 and another using vrEmu6502 on a Pico.
The behaviour of STP in the emu did not correspond to reality, so here is a proposed fix that seems to work well for me.
I am not confident in the new code of the STP-function, it might need some more code, but the patched behaviour of STP reflects what I observe on the WDC65C02 version.

[visrealm]

Thanks for the bug report and proposed fix. Appreciated!

I think your proposed fix is good, but (for minor performance gains where branch prediction isn't available) it might be a reasonable idea to combine jam and stp struct members into a single member. That avoids the second if() (branch) in vrEmu6502Tick. Perhaps we replace jam with stp? I'd also be open to combining the two if() statements into a single one if (vr6502->jam | vr6502->stp)

[NollKollTroll]

I agree, combining the 2 if would be faster and also a bit clearer. I like the single stp version best, jam can use that and still be easy to understand. I have pushed a new version in my fork reflecting this, hopefully it is what you envisioned.

[visrealm]

Looks good, Adam. Merged :)