Run multiple bus ticks for better performance

[beholdnec]

This PR makes the emulator step through multiple bus ticks at a time instead of simulating each tick individually. This gives ~50% performance improvement when running a Mac II at Uncapped speed (about 3.0x instead of 2.0x).

The compact bus still steps one at a time to avoid missed vblanks and hblanks. I haven't found any such issues for Mac II, but please test thoroughly before merging.

[beholdnec]

I'm not sure how to fix

error: could not find native static library SDL2main, perhaps an -L flag is missing?

[twvd]

I'm not sure how to fix

error: could not find native static library SDL2main, perhaps an -L flag is missing?

Building in a MinGW environment on Windows, which I do in GitHub Actions, still requires pkgconfig. I would suggest you retain the original pkgconfig flag behind a feature flag (sdl2_pkgconfig) and set that in the GHA workflow here:

snow/.github/workflows/build_windows.yml

Line 51 in d1923b0

run: cargo build --verbose --release --all -F sdl2-static

You can have a look at the sdl2_bundled flag as an example.

[beholdnec]

I attempted to solve this problem with:

[target.'cfg(unix)'.dependencies]
sdl2 = { version = "0.37.0", features = ["use-pkgconfig"] }

[target.'cfg(not(unix))'.dependencies]
sdl2 = { version = "0.37.0" }

Is cygwin not enabling cfg(unix) ?

[twvd]

I attempted to solve this problem with:

[target.'cfg(unix)'.dependencies]
sdl2 = { version = "0.37.0", features = ["use-pkgconfig"] }

[target.'cfg(not(unix))'.dependencies]
sdl2 = { version = "0.37.0" }

Is cygwin not enabling cfg(unix) ?

It's not cygwin, it's MSYS2 and MinGW which provide a Windows-native build environment, not emulated Unix.

[beholdnec]

I hope I implemented sdl2-pkgconfig correctly, I'm not able to test on all platforms here

[twvd]

I tested your PR but there's some issues; if I emulate a Mac II and pause, then reset the machine and run it again, the emulator core is frozen and will not respond to any more commands.

[beholdnec]

I tested your PR but there's some issues; if I emulate a Mac II and pause, then reset the machine and run it again, the emulator core is frozen and will not respond to any more commands.

Checked in a fix!