pthrr / clashos

multiplayer arcade game for bare metal Raspberry Pi 3 B+

ClashOS

A work-in-progress multiplayer arcade game that runs directly on the Raspberry Pi 3 B+ hardware, written entirely in Zig.

Current Status

"Hello World" OS using the MiniUART. Tested and working on real hardware. It has regressed on real hardware, and I haven't fixed it yet.

Building

zig build

Testing

QEMU

zig build qemu

Debugging with GDB

zig build qemu -Dgdb

In another terminal:

gdb zig-cache/clashos-dbg -ex 'target remote localhost:1234'

Sending a New Kernel Image via Serial

While the Raspberry Pi is running, you can use

zig build upload -Dtty=/dev/ttyUSB0

If using QEMU, use zig build qemu -Dpty and note the tty path. In another terminal window, cat the tty path. In yet another terminal window, you can use the zig build upload command above, with the tty path provided by QEMU. This is compatible with using GDB with QEMU, just make sure to pass the -Dgdb to both zig build commands.

Actual Hardware

1. Mount an sdcard with a single FAT32 partition.
2. Copy boot/* to /path/to/sdcard/*.
3. zig build
4. Copy clashos.bin to /path/to/sdcard/kernel7.img.

For further changes repeat steps 3 and 4.

Roadmap

• Interface with the file system
• Get rid of dependency on binutils objcopy
• Interface with the video driver
• Get a simple joystick and button and use GPIO
• Sound (should it be the analog or over HDMI)?
• Make the game
• Build arcade cabinets

Documentation

EZSync 012 USB Cable

• Black: Pin 6, Ground
• Yellow: Pin 8, BCM 14, TXD / Transmit
• Orange: Pin 10, BCM 15, RXD / Receive

How to view the serial data

Where /dev/ttyUSB0 is the device that represents the serial-to-USB cable:

sudo screen /dev/ttyUSB0 115200 cs8

Memory Layout

0x0000000 (  0 MiB) - boot entry point
0x0001000           - shortExceptionHandlerAt0x1000 function
0x0001100           - kernelMainAt0x1100 function
0x8000000 (128 MiB) - top of kernel stack, and bootloader_main function
0x8800000 (136 MiB) - top of bootloader stack