Cannot print 32 bit integers

[crclark96]

When I try to print a u32 variable above 65535 (u16::MAX), the value wraps to a lower value below 65535. This also occurs with i32 overflowing at i16::MAX.

I made a reproduction here: https://github.com/crclark96/ufmt-i32-print-repro, but I'll copy main source file and output below:

#![no_std]
#![no_main]

extern crate panic_halt;

use arduino_uno::prelude::*;

#[arduino_uno::entry]
fn main() -> ! {
    let dp = arduino_uno::Peripherals::take().unwrap();

    let mut pins = arduino_uno::Pins::new(
        dp.PORTB,
        dp.PORTC,
        dp.PORTD,
    );
    let mut serial = arduino_uno::Serial::new(
        dp.USART0,
        pins.d0,
        pins.d1.into_output(&mut pins.ddr),
        57600.into_baudrate(),
    );

    ufmt::uwriteln!(&mut serial, "unsigned 0..80_000\r").void_unwrap();

    for x in (0u32..80_000u32).step_by(10000) {
        ufmt::uwriteln!(&mut serial, "{}\r", x).void_unwrap();
    }

    ufmt::uwriteln!(&mut serial, "signed 0..80_000\r").void_unwrap();

    for x in (0i32..80_000i32).step_by(10000) {
        ufmt::uwriteln!(&mut serial, "{}\r", x).void_unwrap();
    }

    loop {}
}

Output:

unsigned 0..80_000
0
10000
20000
30000
40000
50000
60000
4464
signed 0..80_000
0
10000
20000
30000
-25536
-15536
-5536
4464

[Serentty]

I got the same issue writing code for the 6502. I think I've figured out the problem, and it's that the implementation for printing 32-bit integers casts them to a usize first. I have no idea why it would be implemented in such a non-portable way.