#![no_std]
#![no_main]

extern crate vexriscv;

#[macro_use]
mod debug;

mod definitions;
mod irq;
mod macros;
mod mem;
mod processtable;
mod syscalls;
mod timer;

pub use irq::sys_interrupt_claim;

use core::panic::PanicInfo;
use mem::MemoryManager;
use processtable::ProcessTable;
use vexriscv::register::{mcause, mepc, mie, mstatus, vmim, vmip};
use xous_kernel_riscv_rt::xous_kernel_entry;

#[panic_handler]
fn handle_panic(arg: &PanicInfo) -> ! {
    println!("PANIC!");
    println!("Details: {:?}", arg);
    loop {}
}

#[xous_kernel_entry]
fn xous_main() -> ! {
    unsafe {
        vmim::write(0); // Disable all machine interrupts
        mie::set_msoft();
        mie::set_mtimer();
        mie::set_mext();
        mstatus::set_mie(); // Enable CPU interrupts
    }

    let uart = debug::DEFAULT_UART;
    sys_interrupt_claim(0, timer::irq).unwrap();
    timer::time_init();

    // Enable "RX_EMPTY" interrupt
    uart.enable_rx();

    println!("Starting up...");
    sys_interrupt_claim(2, debug::irq).unwrap();

    println!("Creating memory manager...");
    let mm = MemoryManager::new();

    println!("Creating process table...");
    ProcessTable::new(mm, kmain);
}

fn kmain(mm: MemoryManager, pt: ProcessTable) -> ! {
    println!("Entering main loop");
    let mut last_time = timer::get_time();
    loop {
        let new_time = timer::get_time();
        if new_time >= last_time + 1000 {
            last_time = new_time;
            println!("Uptime: {} ms", new_time);
        }
        // unsafe { vexriscv::asm::wfi() };
    }
}

#[no_mangle]
pub fn trap_handler() {
    let mc = mcause::read();
    let irqs_pending = vmip::read();

    if mc.is_exception() {
        println!("CPU Exception");
        println!("{:?} @ PC: {:08x}", mc.cause(), mepc::read());
        unsafe { vexriscv::asm::ebreak() };
        loop {}
    }

    if irqs_pending != 0 {
        irq::handle(irqs_pending);
    }
}