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.
Events scheduled more than 4.12 seconds in the future (2.96 seconds for
Wii games) would overflow the sign bit and get scheduled in the past
instead, causing them to fire instantly.
Previously GlobalTimer was only updated at the end of each slice
when CoreTiming::Advance() was called, so it could be upto 20,000
cycles off.
This was causing huge problems with games which made heavy use of
the time base register, such as OoT (virtual console) and Pokemon
puzzle.
I've also made it so event scheduling will be accurate to the jit
block level, instead of accurate to the slice.
This isn't technically the correct place to have the downcount variable, but it is similar to what PPSSPP does to gain a bit of extra speed on ARM.
We access this variable quite a bit, with each exit in a block it is subtracted from.
On ARM this required four instructions to load and store the value, while now it only requires two.
This gives an average of 1FPS gain to most games.
Examples:
Crazy Taxi: 54FPS -> 55FPS
Luigi's Mansion: 20FPS -> 21FPS
Wind Waker(Save Screen): 27FPS -> 28FPS
This seems to average a 6mhz to 16mhz CPU core emulation improvement in the few games I've tested.
