SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
Fixes https://bugs.dolphin-emu.org/issues/10265 (Star Wars: The Clone
Wars hangs on loading screen with DSP-HLE and JIT Recompiler).
The Clone Wars hangs upon initial boot if this interrupt happens too
quickly after submitting a command list. When played in DSP-LLE, the
interrupt lags by about 160,000 cycles, though any value greater than or
equal to 814 will work. In other games, the lag can be as small as 50,000
cycles (in Metroid Prime) and as large as 718,092 cycles (in Tales of
Symphonia!).
All credit to @hthh, who put in a heroic(!) amount of detective work and
discovered that The Clone Wars tracks a "AXCommandListCycles" variable
which matches the aforementioned 160,000 cycles. It's initialized to ~2500
cycles for a minimal, empty command list, so that should be a safe number
for pretty much anything a game does (*crosses fingers*).
This implements MIOS's PPC bootstrapping functionality, which enables
users to start a GameCube game from the Wii System Menu.
Because we aren't doing Starlet LLE (and don't have a boot1), we can
just jump to MIOS when the emulated software does an ES_LAUNCH or uses
ioctlv 0x25 to launch BC.
Note that the process is more complex on a real Wii and goes through
several more steps before getting to MIOS:
* The System Menu detects a GameCube disc and launches BC (1-100)
instead of the game. [Dolphin does this too.]
* BC, which is reportedly very similar to boot1, lowers the Hollywood
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.
MIOS runs instead of IOS in GC mode and has an embedded GC IPL (which
is the code actually responsible for loading the disc game) and a PPC
bootstrap code. To get things working properly, we simply need to load
both to memory, then jump to the bootstrap code at 0x3400.
Obviously, because of the way this works, a real MIOS is required.
Now that our timings are much more accurate it doesn't look like we
need it anymore. And the instant ARAM DMA mode + scheduling fixes
ctually breaks ATV: Quad Power Racing 2 (causing all sorts of werid
bugs).
Detects a situation where the game is writing to the dcache at the address being DMA'd. As we do not have dcache emulation, invalid data is being DMA'd causing audio glitches. The following code detects this and enables the DMA to complete instantly before the invalid data is written.
Added accurate ARAM DMA transfer timing.
Removed the addition of DSP exception checking.
