//! mem — show memory statistics via the exports table.

#![no_std]
#![no_main]

#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
    loop { core::hint::spin_loop(); }
}

fn put(exports: &rsapi::Exports, buf: &[u8]) {
    (exports.put_line)(rsapi::Line { ptr: buf.as_ptr(), len: buf.len() });
}

fn fmt_kib(exports: &rsapi::Exports, v: u64) {
    let mut buf = [0u8; 32];
    let kb = v / 1024;
    let mut i = buf.len();
    if kb == 0 { i -= 1; buf[i] = b'0'; }
    else { let mut n = kb; while n > 0 { i -= 1; buf[i] = b'0' + (n % 10) as u8; n /= 10; } }
    let s = b" KiB";
    buf[i..i+s.len()].copy_from_slice(s);
    put(exports, &buf[i..i+s.len()]);
}

#[unsafe(no_mangle)]
pub extern "C" fn efi_main(exports: &'static rsapi::Exports, _argc: usize, _argv: *const rsapi::Arg) -> i32 {
    let mut s = rsapi::MemStats { heap_total: 0, heap_free: 0, pages_total: 0, pages_free: 0 };
    (exports.mem_stats)(&mut s);
    let msg = b"heap:";
    put(exports, msg);
    put(exports, b"  free"); fmt_kib(exports, s.heap_free);
    put(exports, b" / total"); fmt_kib(exports, s.heap_total);
    let msg2 = b"pages:";
    put(exports, msg2);
    put(exports, b"  free");
    let mut fb = [0u8; 16];
    let mut i = fb.len();
    let n = s.pages_free; if n==0 { i-=1; fb[i]=b'0'; } else { let mut m=n; while m>0 { i-=1; fb[i]=b'0'+(m%10) as u8; m/=10; } }
    put(exports, &fb[i..]);
    put(exports, b" / ");
    let mut tb = [0u8; 16];
    let mut j = tb.len();
    let t = s.pages_total; if t==0 { j-=1; tb[j]=b'0'; } else { let mut m=t; while m>0 { j-=1; tb[j]=b'0'+(m%10) as u8; m/=10; } }
    put(exports, &tb[j..]);
    0
}