CP15 Cache Emulation Work

melonDS-emu / melonDS

DS emulator, sorta

https://melonds.kuribo64.net

GNU General Public License v3.0

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CP15 Cache Emulation Work #1955

Open DesperateProgrammer opened 5 months ago

DesperateProgrammer commented 5 months ago

The instruction and data cache register were not yet implemented in MelonDS and would act different against the hardware by just reading/writing them.

They have no impact on the - not yet implemented - data cache nor on the instruction cache until their implementation progresses.

DesperateProgrammer commented 5 months ago

I'll add some more changes to the CP15 Caching Instructions and Handling here.

DesperateProgrammer commented 5 months ago

The last commit was a bit bigger / combined, as adding DCache required other things to not break some applications.

Instruction cache is working except:

Prefetch via CP15 (todo)
CacheLockdown has no effect yet
Timings on cache-fill are not correct yet Data cache is working except:
- Timings on cache fill are not correct yet
- Timings on Cache hit are not correct yet
- CacheLockdown has no effect yet
- WriteBack is not implemented yet (it writes through and invalidates the cache line atm)

CP15 Registers Operations:

Cache Clean has no effect yet (needs write back mechanism)
Cache Clean & Invalidate will now also invalidate the cache (was missing)
Cache Debug Index Register was added
ICache/DCache Tag Registers were added
ICache/DCache Data Registers are not done yet
Privileged/User Checks are missing

DesperateProgrammer commented 5 months ago

Update on the status

Instruction cache is working except:

Prefetch via CP15 (todo)
Timings on cache-fill are not correct yet

Data cache is working except:

Timings on cache fill are not correct yet
WriteBack is not implemented yet (it writes through)

CP15 Registers Operations:

Cache Clean has no effect yet (needs write back mechanism)
Cache Clean & Invalidate will now also invalidate the cache (was missing)
Cache Debug Index Register is working
ICache/DCache Tag Registers are working
ICache/DCache Data Registers are working
Privileged/User Checks are missing

JIT:

Caches are now disabled when JIT is enabled and no longer breaks JIT.

DesperateProgrammer commented 5 months ago

This turned out to be quite some rework for the CP15. The Cache is now working including the write-back mode. Cache Debug registers, BIST Cache Test register CP15 Registers and Functions received some documenting comments. Many CP15 related calls received the const-specifier for its arguments when they are not changed in the call.

KostaSaizo7 commented 3 months ago

Fixes https://github.com/melonDS-emu/melonDS/issues/380

KostaSaizo7 commented 3 months ago

Unfortunately https://github.com/melonDS-emu/melonDS/issues/359 is still occuring

Jaklyy commented 2 months ago

seems like disabling the pu via the control reg causes melonds to hang under this pr? at least reproduceable under this test rom: zboxtesttest.zip

DesperateProgrammer commented 2 months ago

Thanks for the report and sample Jakly,

I'll check that as soon i got some time.