I'm writing some embedded code using this crate to buffer USB data. To read data, I have to call a read_packet(&mut [u8]) method, but accessing an ArrayDeque's backing array directly then setting the length is currently impossible.
I could create an array, read into it, then extend, but I'd prefer to use the deque rather than allocating memory for every packet:
let mut usb = ...;
let mut buf = ArrayDeque::<_, 128>::default();
const PKT_SIZE: usize = 64;
assert!(buf.capacity() - buf.len() >= PKT_SIZE);
let mut packet = [0; PKT_SIZE];
let read_count = usb.read_packet(&mut packet)?;
buf.extend_back(packet[..read_count].iter().copied());
If I know a whole packet can fit at the deque's tail, say it's empty and contiguous, I should be able to read into the buffer like this safely:
buf.linearize();
assert!(buf.is_empty());
unsafe {
let slice = MaybeUninit::slice_assume_init_mut(buf.as_uninit_slice_mut());
let read_count = usb.read_packet(&mut slice[..PKT_SIZE])?;
// set_len?
}But now how do I "grow" the deque to inform it of the new elements? Exposing set_len as is (unsafe) would help in this use case
I'm writing some embedded code using this crate to buffer USB data. To read data, I have to call a
read_packet(&mut [u8])method, but accessing anArrayDeque's backing array directly then setting the length is currently impossible.I could create an array, read into it, then extend, but I'd prefer to use the deque rather than allocating memory for every packet:
If I know a whole packet can fit at the deque's tail, say it's empty and contiguous, I should be able to read into the buffer like this safely:
But now how do I "grow" the deque to inform it of the new elements? Exposing
set_lenas is (unsafe) would help in this use case