Volume is a f32 value. (SwIPC describes it as a u32, but it is actually f32 as corroborated by switchbrew docs and SetAudioDeviceOutputVolume)
```cpp
const f32 volume = rp.Pop<f32>();
```
If an unmapping operation fails, we shouldn't be decrementing the amount
of memory mapped and returning that the operation was successful. We
should actually be returning the error code in this case.
Avoids potentially expensive (depending on the size of the memory block)
allocations by reserving the necessary memory before performing both
insertions. This avoids scenarios where the second insert may cause a
reallocation to occur.
Avoids needing to read the same long sequence of code in both code
paths. Also makes it slightly nicer to read and debug, as the locals
will be able to be shown in the debugger.
This commit ensures that all backing memory allocated for the Guest CPU
is aligned to 256 bytes. This due to how gpu memory works and the heavy
constraints it has in the alignment of physical memory.
Audio devices use the supplied revision information in order to
determine if USB audio output is able to be supported. In this case, we
can only really handle using this revision information in
ListAudioDeviceName(), where it checks if USB audio output is supported
before supplying it as a device name.
A few other scenarios exist where the revision info is checked, such as:
- Early exiting from SetAudioDeviceOutputVolume if USB audio is
attempted to be set when that device is unsupported.
- Early exiting and returning 0.0f in GetAudioDeviceOutputVolume when
USB output volume is queried and it's an unsupported device.
- Falling back to AHUB headphones in GetActiveAudioDeviceName when the
device type is USB output, but is unsupported based off the revision
info.
In order for these changes to also be implemented, a few other changes
to the interface need to be made.
Given we now properly handle everything about ListAudioDeviceName(), we
no longer need to describe it as a stubbed function.
The revision querying facilities are used by more than just audren. e.g.
audio devices can use this to test whether or not USB audio output is
supported.
This will be used within the following change.
AudioDevice and AudioInterface aren't valid device names on the Switch.
We should also be returning consistent names in
GetActiveAudioDeviceName().
While we're at it, we can also handle proper name output in
ListAudioDeviceName, by returning all the available devices on the
Switch.
