use core::future::Future;
pub trait AsyncTransfer {
type Error;
type TransferFuture<'f>: Future<Output = Result<(), Self::Error>>;
fn async_transfer<'a>(&'a mut self, data: &'a mut [u8]) -> Self::TransferFuture<'a>;
}
pub trait AsyncWrite {
type Error;
type WriteFuture<'f>: Future<Output = Result<(), Self::Error>>;
fn async_write<'a>(&'a mut self, data: &'a [u8]) -> Self::WriteFuture<'_>;
}
pub trait AsyncWriteIter {
type Error;
type WriteIterFuture<'f>: Future<Output = Result<(), Self::Error>>;
fn async_write_iter<'a>(
&'a mut self,
data: &'a mut dyn Iterator<Item = u8>,
) -> Self::WriteIterFuture<'_>;
}
pub mod transfer {
use super::AsyncTransfer;
use core::future::Future;
use core::pin::Pin;
use core::task::{Context, Poll};
pub trait Default: embedded_hal::spi::FullDuplex<u8> {}
impl<S: Default + 'static> AsyncTransfer for S {
type Error = S::Error;
type TransferFuture<'f> = DefaultTransferFuture<'f, S>;
fn async_transfer<'a>(&'a mut self, data: &'a mut [u8]) -> Self::TransferFuture<'a> {
DefaultTransferFuture {
spi: self,
data,
offset: 0,
state: State::Sending,
}
}
}
enum State {
Sending,
Receiving,
}
pub struct DefaultTransferFuture<'a, S> {
spi: &'a mut S,
data: &'a mut [u8],
offset: usize,
state: State,
}
impl<'a, S: Default> Future for DefaultTransferFuture<'a, S> {
type Output = Result<(), S::Error>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
while self.offset < self.data.len() {
match self.state {
State::Sending => {
let byte = self.data[self.offset];
match self.spi.send(byte) {
Ok(()) => {
self.state = State::Receiving;
continue;
}
Err(nb::Error::Other(e)) => {
return Poll::Ready(Err(e));
}
Err(nb::Error::WouldBlock) => {
cx.waker().wake_by_ref();
return Poll::Pending;
}
}
}
State::Receiving => match self.spi.read() {
Ok(byte) => {
let offset = self.offset;
self.data[offset] = byte;
self.offset += 1;
self.state = State::Sending;
continue;
}
Err(nb::Error::Other(e)) => {
return Poll::Ready(Err(e));
}
Err(nb::Error::WouldBlock) => {
cx.waker().wake_by_ref();
return Poll::Pending;
}
},
}
}
Poll::Ready(Ok(()))
}
}
}