Add chess game

[vinc]

I have been waiting for months for this one, running my chess engine inside my own OS!

This will provide a game to MOROS but also a way to benchmark performance in the OS.

See vinc/littlewing#81

[vinc]

Starting a game of chess:

And after a few moves:

[vinc]

Next step: add a perft command to the cli and avoid panicking when parsing a wrong move.

[vinc]

The perft command test the moves generation of a chess engine by counting the number of moves that can be done from a position at different depths. For example from the starting position there is 20 possible moves for the white pieces, then 400 replies from the black pieces and so on. It can be used as a benchmark if we count how long it takes to count all the pieces at a given depth.

This is what we get on the host system:

> perft
perft 1 -> 20 (0.00 s, 5.28e5 nps)
perft 2 -> 400 (0.00 s, 9.96e5 nps)
perft 3 -> 8902 (0.01 s, 1.38e6 nps)
perft 4 -> 197281 (0.04 s, 5.19e6 nps)
perft 5 -> 4865609 (0.86 s, 5.65e6 nps)
perft 6 -> 119060324 (21.18 s, 5.62e6 nps)

And this is in MOROS with QEMU:

> perft
perft 1 -> 20 (0.00 s, 6.67e3 nps)
perft 2 -> 400 (0.00 s, 2.00e5 nps)
perft 3 -> 8902 (0.05 s, 1.78e5 nps)
perft 4 -> 197281 (0.97 s, 2.04e5 nps)
perft 5 -> 4865609 (24.14 s, 2.02e5 nps)
^C

On VirtualBox it's faster, we get this:

perft 1 -> 20 (0.00 s, 2.00e4 nps)
perft 2 -> 400 (0.00 s, 4.00e5 nps)
perft 3 -> 8902 (0.00 s, 2.23e6 nps)
perft 4 -> 197281 (0.08 s, 2.38e6 nps)
perft 5 -> 4865609 (1.38 s, 3.53e6 nps)
perft 6 -> 119060324 (28.62 s, 4.16e6 nps)

Which is pretty good!

And finally on baremetal we get this:

perft 1 -> 20 (0.00 s, inf nps)
perft 2 -> 400 (0.00 s, inf nps)
perft 3 -> 8902 (0.00 s, 2.97e6 nps)
perft 4 -> 197281 (0.07 s, 2.98e6 nps)
perft 5 -> 4865609 (1.67 s, 2.91e6 nps)
perft 6 -> 119060324 (41.13 s, 2.89e6 nps)

Which is worse, probably because the kernel has some optimizations disabled at compile time and there's no hypervisor to add them back.

[vinc]

The game experience is starting to look good enough for now, just need to implement what happen at the end of a game.

[vinc]

With endgame support:

And the help command:

The first iteration is more or less done.