GameCube Zelda HLE in Wii mode

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No description provided.

[Pokechu22]

Can you provide some context as to where this is useful?

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Running GameCube games in Wii mode can be useful for modding simply because of the additional hardware. To get audio to work on console and with LLE, the simplest approach is to patch ARAlloc to add 0x10000000 to addresses (since the ARAM addresses would be in MEM1 which is not what we want) and to patch ARQPostRequest to turn it into a memcpy. However, this breaks HLE, thus this PR.

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Here is a DOL (in the out folder) that applies these patches to Mario Kart: Double Dash!! and the corresponding source code (for reference only, that project is early and doesn't yet have build instructions). source.zip Update: the project is now available at https://github.com/doubledashdeluxe/ddd.

[dreamsyntax]

Do you have an example of patching any GC dol? I would want to test this on a few different GC.

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Do you have an example of patching any GC dol? I would want to test this on a few different GC.

I don't have other GameCube games on hand, but here is a minimal template. This will likely not work on a real console or with out of region games, but should work on Dolphin with the right fallback region.

[JMC47]

I'm guessing when we boot games from the Wii System Menu, Dolphin is cheating and just swapping to GameCube mode, hence this PR? I've definitely booted Wind Waker from the Wii System Menu before.

[Pokechu22]

Yes, dolphin cheats by immediately loading MIOS when BC is loaded:

dolphin/Source/Core/Core/IOS/ES/ES.cpp

Lines 351 to 365 in 44c90aa

	bool ESDevice::LaunchIOS(u64 ios_title_id, HangPPC hang_ppc)
	{
	// A real Wii goes through several steps before getting to MIOS.
	//
	// * The System Menu detects a GameCube disc and launches BC (1-100) instead of the game.
	// * BC (similar to boot1) lowers the clock speed to the Flipper's and then launches boot2.
	// * boot2 sees the lowered clock speed and launches MIOS (1-101) instead of the System Menu.
	//
	// Because we don't have boot1 and boot2, and BC is only ever used to launch MIOS
	// (indirectly via boot2), we can just launch MIOS when BC is launched.
	if (ios_title_id == Titles::BC)
	{
	NOTICE_LOG_FMT(IOS, "BC: Launching MIOS...");
	return LaunchIOS(Titles::MIOS, hang_ppc);
	}

and also has MIOS switch stuff into GameCube mode:

dolphin/Source/Core/Core/IOS/MIOS.cpp

Lines 33 to 55 in 44c90aa

	static void ReinitHardware()
	{
	SConfig::GetInstance().bWii = false;
	// IOS clears mem2 and overwrites it with pseudo-random data (for security).
	auto& system = Core::System::GetInstance();
	auto& memory = system.GetMemory();
	std::memset(memory.GetEXRAM(), 0, memory.GetExRamSizeReal());
	// MIOS appears to only reset the DI and the PPC.
	// HACK However, resetting DI will reset the DTK config, which is set by the system menu
	// (and not by MIOS), causing games that use DTK to break. Perhaps MIOS doesn't actually
	// reset DI fully, in such a way that the DTK config isn't cleared?
	// system.GetDVDInterface().ResetDrive(true);
	system.GetPowerPC().Reset();
	Wiimote::ResetAllWiimotes();
	// Note: this is specific to Dolphin and is required because we initialised it in Wii mode.
	auto& dsp = system.GetDSP();
	dsp.Reinit(Config::Get(Config::MAIN_DSP_HLE));
	dsp.GetDSPEmulator()->Initialize(SConfig::GetInstance().bWii,
	Config::Get(Config::MAIN_DSP_THREAD));
	SystemTimers::ChangePPCClock(SystemTimers::Mode::GC);
	}

That said, the way dolphin cheats is close to what happens on real hardware, just skipping lots of low level IOS emulation stuff; when running a GameCube game on a Wii, the Wii is in GameCube mode and most additional hardware is disabled. My understanding is that this PR is to make running GameCube games modified to run in Wii mode work on Dolphin with DSP HLE the same way it would work when loading such modified games on a real Wii (or on Dolphin with DSP LLE). It doesn't do anything that would apply when running unmodified GameCube games, even when booting them via the Wii Menu.

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My understanding is that this PR is to make running GameCube games modified to run in Wii mode work on Dolphin with DSP HLE the same way it would work when loading such modified games on a real Wii (or on Dolphin with DSP LLE). It doesn't do anything that would apply when running unmodified GameCube games, even when booting them via the Wii Menu.

Indeed.

[JMC47]

Is anyone blocking this? I don't see a reason to block it if it won't affect anything outside of some mods that use it.

[Pokechu22]

This comment probably should be rewritten, since m_aram_base_addr = 0 no longer behaves differently (and SetARAMBaseAddr would never be called because command 0xE doesn't exist in GameCube uCode). I'm not 100% sure what it should say though.

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Came up with something, hopefully the wording is clear enough.

[Pokechu22]

Looks good to me.

I don't think AX needs a similar change, as it doesn't use GetARAMPtr, but I'm not super familiar with the details of it.

[dreamsyntax]

Not worth blocking over IMO, but I've heard mention of deferring SConfig to instead use the new config

[Pokechu22]

bWii isn't something that would make sense to move to the new config system since it's not an actual setting, more of a global variable. It probably doesn't make sense to have it in SConfig, but moving it somewhere else would be part of a larger refactor (which is definitely out of scope for this PR).

[JosJuice]

Agreed. Adding new settings to SConfig would be rejected, but it's fine to keep using whatever is in there for the time being.