#![no_std]
#![feature(linkage)]
#![feature(panic_info_message)]

#[macro_use]
pub mod console;
mod lang_items;
mod syscall;

#[no_mangle]
#[link_section = ".text.entry"]
pub extern "C" fn _start() -> ! {
    exit(main());
    panic!("unreachable after sys_exit!");
}

#[linkage = "weak"]
#[no_mangle]
fn main() -> i32 {
    panic!("Cannot find main!");
}

#[repr(C)]
#[derive(Debug, Default)]
pub struct TimeVal {
    pub sec: usize,
    pub usec: usize,
}

impl TimeVal {
    pub fn new() -> Self {
        Self::default()
    }
}

use syscall::*;

pub fn write(fd: usize, buf: &[u8]) -> isize {
    sys_write(fd, buf)
}
pub fn exit(exit_code: i32) -> isize {
    sys_exit(exit_code)
}
pub fn yield_() -> isize {
    sys_yield()
}
pub fn get_time() -> isize {
    let time = TimeVal::new();
    match sys_get_time(&time, 0) {
        0 => ((time.sec & 0xffff) * 1000 + time.usec / 1000) as isize,
        _ => -1,
    }
}

pub fn sbrk(size: i32) -> isize {
    sys_sbrk(size)
}

pub fn munmap(start: usize, len: usize) -> isize {
    sys_munmap(start, len)
}

pub fn mmap(start: usize, len: usize, prot: usize) -> isize {
    sys_mmap(start, len, prot)
}

pub fn sleep(period_ms: usize) {
    let start = get_time();
    while get_time() < start + period_ms as isize {
        sys_yield();
    }
}