//! Writing an [OS] in Rust
//!
//! [os]: https://os.phil-opp.com
#![no_std]
#![no_main]
#![feature(custom_test_frameworks)]
#![test_runner(rustos::test_runner)]
#![reexport_test_harness_main = "test_main"]
#![feature(abi_x86_interrupt)]
extern crate rustos;
use core::panic::PanicInfo;
use rustos::println;

#[no_mangle]
pub extern "C" fn _start() -> ! {
    println!("Welcome to the real world!");
    init();
    use x86_64::registers::control::Cr3;
    let (level_4_page_table, _) = Cr3::read();
    println!("Level 4 page table at: {:?}", level_4_page_table);
    #[cfg(test)]
    test_main();
    println!("It did not crash!!!");
    rustos::hlt_loop();
}

#[cfg(not(test))]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    println!("{}", info);
    rustos::hlt_loop();
}

#[cfg(test)]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    rustos::test_panic_handler(info)
}

extern crate lazy_static;
extern crate x86_64;
use lazy_static::lazy_static;
use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};

fn init() {
    IDT.load();
}

lazy_static! {
    static ref IDT: InterruptDescriptorTable = {
        let mut idt = InterruptDescriptorTable::new();
        idt.page_fault.set_handler_fn(page_fault_handler);
        idt
    };
}

extern "x86-interrupt" fn page_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    error_code: PageFaultErrorCode,
) {
    use x86_64::registers::control::Cr2;
    println!("EXCEPTION: PAGE FAULT");
    println!("Accessed Address: {:?}", Cr2::read());
    println!("Error Code: {:?}", error_code);
    println!("{:#?}", stack_frame);
    rustos::hlt_loop();
}