rusty-hermit 0.3.54

//! Kernel Message Buffer for Multi-Kernel mode.
//! Can be read from the Linux side as no serial port is available.

use core::sync::atomic::{AtomicUsize, Ordering};
use crossbeam_utils::CachePadded;

const KMSG_SIZE: usize = 0x1000;

#[repr(C)]
struct KmsgSection {
	buffer: CachePadded<[u8; KMSG_SIZE + 1]>,
}

static mut KMSG: KmsgSection = KmsgSection {
	buffer: CachePadded::new([0; KMSG_SIZE + 1]),
};

static BUFFER_INDEX: CachePadded<AtomicUsize> = CachePadded::new(AtomicUsize::new(0));

pub fn write_byte(byte: u8) {
	let index = BUFFER_INDEX.fetch_add(1, Ordering::SeqCst);
	unsafe {
		core::ptr::write_volatile(&mut KMSG.buffer[index % KMSG_SIZE], byte);
	}
}