* Move out boot parameters to a separate struct, which is not part
of SConfig/ConfigManager because there is no reason for it to
be there.
* Move out file name parsing and constructing the appropriate params
from paths to a separate function that does that, and only that.
* For every different boot type we support, add a proper struct with
only the required parameters, with descriptive names and use
std::variant to only store what we need.
* Clean up the bHLE_BS2 stuff which made no sense sometimes. Now
instead of using bHLE_BS2 for two different things, both for storing
the user config setting and as a runtime boot parameter,
we simply replace the Disc boot params with BootParameters::IPL.
* Const correctness so it's clear what can or cannot update the config.
* Drop unused parameters and unneeded checks.
* Make a few checks a lot more concise. (Looking at you, extension
checks for disc images.)
* Remove a mildly terrible workaround where we needed to pass an empty
string in order to boot the GC IPL without any game inserted.
(Not required anymore thanks to std::variant and std::optional.)
The motivation for this are multiple: cleaning up and being able to add
support for booting an installed NAND title. Without this change, it'd
be pretty much impossible to implement that.
Also, using std::visit with std::variant makes the compiler do
additional type checks: now we're guaranteed that the boot code will
handle all boot types and no invalid boot type will be possible.
I didn't know better back then, but the boot type is only supposed to
be used for the actual boot params. It shouldn't be used or changed
after booting.
- coef: Explicitly set 23 different values that are used by GBA UCode,
and tweaked overall parameters to more closely match those 23 values.
- irom: Moved a few functions to their proper places, updated BootUCode
to configure DMA transfers using AX registers as well as IX registers
(the GBA UCode uses this to do two sequential transfers in one call),
and added partial functions used by GBA UCode.
All functions were reverse-engineered solely based off of observed
effects on the virtual machine: register states before-and-after, dmem
interactions, and DMA transfers. The specific coefficients were observed
being read from dmem, and must be exactly those values to function
properly. I have no knowledge of how the official ROM implements these
functions, or how it is implemented overall.
Tested with The Legend of Zelda: Four Swords Adventures, Final Fantasy
Crystal Chronicles, and Billy Hatcher and the Giant Egg (to download
ChuChu Rocket!).
`P_REG1C` had the same value as `P_ACCL`, so was causing spurious errors
when used with ACCM registers. Gcdsptool (which calls this `P_ACCLM`)
gives it the value `P_REG | 0x1c10` instead, and handles errors in the
same block as other REG## enums.
