Cycle-accurate emulator 👌
Description
To become a rock star emulator Boytacean has to provide cycle-accurate emulation.
Many tests would allow testing of the cycle-accurate components.
More information can be found here (Game Boy emulator testing).
There is also some good feedback in a Boytacean Reddit post reply that brings some insights on why some games fail to be emulated.
There's a good comparison of emulators that can be used as a reference for the tests they pass: https://daid.github.io/GBEmulatorShootout/.
Some of the Blargg tests may help in the implementation of a more accurate emulator, listed per order of interest here:
- https://github.com/retrio/gb-test-roms/blob/master/interrupt_time/interrupt_time.s
- https://github.com/retrio/gb-test-roms/blob/master/mem_timing/readme.txt
A good emulator to obtain inspiration is:
https://github.com/7thSamurai/Azayaka
Sameboy also adopts the same pre-emptive cycle jumping strategy as we can see here:
https://github.com/LIJI32/SameBoy/blob/master/Core/sm83_cpu.c#L353C9-L353C26
Challenges
One of the most significant issues preventing Boytacean from reaching cycle accuracy is the inability to trigger the clock from every single component - most notably the CPU.
It must be possible to trigger a new clock at every stage of the CPU processing. This ability must exist without any significant performance impact.
Related
Reference
