This adds about a frame of latency, and since most games don't change
VI registers during scanout, we can get away with outputting the XFB at
the start of scanout. WWE Crush Hour is the (only currently known)
exception, which has flickering problems when doing it this way.
This adds a path to perform the output at the end of scanout, and gates
it behind an option which defaults to using the latency-reducing
pre-scanout path.
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.
The STL has everything we need nowadays.
I have tried to not alter any behavior or semantics with this
change wherever possible. In particular, WriteLow and WriteHigh
in CommandProcessor retain the ability to accidentally undo
another thread's write to the upper half or lower half
respectively. If that should be fixed, it should be done in a
separate commit for clarity. One thing did change: The places
where we were using += on a volatile variable (not an atomic
operation) are now using fetch_add (actually an atomic operation).
Tested with single core and dual core on x86-64 and AArch64.
Makes the values strongly-typed and gets more identifiers out of the
global namespace.
We are forced to use anything that is not "None" to mean none, because
X11 is garbage in that it has:
\#define None 0L
Because clearly no one else will ever want to use that identifier for
anything in their own code (and is why you should prefix literally
any and all preprocessor macros you expose to library users in public
headers).
This fixes the global-static fifo object causing infinite hangs in some
cases. Notably, failure to initialize a graphics backend would result in
BlockingLoop::Prepare being called but never executing Run(), leaving the
object in a bad state.
