main.rs

#![no_std]
#![no_main]
#![feature(asm_sym)]
#![feature(naked_functions)]

use blue_loader_stage3::{realmode, realmode_asm};

extern "sysv64" {
    static REALMODE_IMAGE: &'static [u8];
    static mut REALMODE: &'static mut [u8];
    static mut BSS: &'static mut [u8];
}

fn blue() {
    unsafe {
        // blue
        core::arch::asm!(
            "mov edi, 0xb8000",
            "mov rcx, 500",
            "mov rax, 0x1F201F201F201F20",
            "rep stosq",
        );
    }
}

pub fn printc(c: u8) {
    unsafe {
        realmode::WORK[0] = c;
        realmode::WORK[1] = 0x0e;
        realmode_asm!(
            "push ebx",
            "mov ax, [{work}]",
            "mov ebx, 7",
            "int 0x10",
            "pop ebx",
        );
    }
}

pub fn inform(s: &[u8]) {
    for &c in s {
        printc(c);
    }
}

#[link_section = ".startup"]
#[no_mangle]
extern "cdecl" fn _start() -> ! {
    // move realmode section to true home, zero bss
    unsafe {
        REALMODE.copy_from_slice(REALMODE_IMAGE);
        BSS.fill(0);
    }

    inform(b"BLUEloader/3\r\n");

    panic!("end of stage3");
}