From b801592dc31b6ad3839fb2d84bb8893702a3d84f Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Wed, 24 May 2023 00:21:46 +0800
Subject: [PATCH] Implement BufRead for CDCRead, fix Write impl
---
embassy/demos/picow/src/usbserial.rs | 73 ++++++++++++++++++----------
1 file changed, 46 insertions(+), 27 deletions(-)
diff --git a/embassy/demos/picow/src/usbserial.rs b/embassy/demos/picow/src/usbserial.rs
index 4bd7f73..272f582 100644
--- a/embassy/demos/picow/src/usbserial.rs
+++ b/embassy/demos/picow/src/usbserial.rs
@@ -12,7 +12,8 @@ use embassy_usb::class::cdc_acm::{self, CdcAcmClass, State};
use embassy_usb::Builder;
use embassy_usb_driver::Driver;
-use embedded_io::{asynch, Io};
+use embedded_io::{asynch, Io, asynch::BufRead};
+
use heapless::Vec;
use sunset::*;
@@ -112,40 +113,58 @@ impl<'a, D: Driver<'a>> asynch::Read for CDCRead<'a, '_, D> {
async fn read(&mut self, ret: &mut [u8]) -> sunset::Result<usize> {
debug_assert!(self.start < self.end || self.end == 0);
- // return existing content first
- if self.end > 0 {
- let l = ret.len().min(self.end - self.start);
- ret.copy_from_slice(&self.buf[self.start..self.start + l]);
- self.start += l;
- if self.start == self.end {
- self.start = 0;
- self.end = 0;
- }
- return Ok(l);
+ if self.end == 0 && ret.len() > self.buf.len() {
+ // perform an unbuffered read if possible, saves a copy
+ let n = self
+ .cdc
+ .read_packet(ret)
+ .await
+ .map_err(|_| sunset::Error::ChannelEOF)?;
+ info!("direct read_packet {:?}", &ret[..n]);
+ return Ok(n)
}
- debug_assert!(self.start == 0);
- debug_assert!(self.end == 0);
-
- let (r, buffered) = if ret.len() >= self.buf.len() {
- // read in-place
- (self.cdc.read_packet(ret).await, false)
- } else {
- // ret is too small, use buffer
- (self.cdc.read_packet(self.buf.as_mut()).await, true)
- };
+ let b = self.fill_buf().await?;
+ let n = ret.len().min(b.len());
+ info!("buf read {:?}, rl {} bl {}", &b[..n], ret.len(), b.len());
+ (&mut ret[..n]).copy_from_slice(&b[..n]);
+ self.consume(n);
+ return Ok(n)
+ }
+}
+impl<'a, D: Driver<'a>> asynch::BufRead for CDCRead<'a, '_, D> {
+ async fn fill_buf(&mut self) -> sunset::Result<&[u8]> {
+ debug_assert!(self.start < self.end || self.end == 0);
- let n = r.map_err(|_| sunset::Error::ChannelEOF)?;
+ if self.end == 0 {
+ debug_assert!(self.start == 0);
+ let n = self
+ .cdc
+ .read_packet(self.buf.as_mut())
+ .await
+ .map_err(|_| sunset::Error::ChannelEOF)?;
+ info!("buf read_packet {:?}", &self.buf[..n]);
- if n == 0 {
- return Err(sunset::Error::ChannelEOF);
+ self.end = n;
}
+ debug_assert!(self.end > 0);
+ info!("fill {}..{}", self.start, self.end);
+
+ return Ok(&self.buf[self.start..self.end]);
+ }
+
+ fn consume(&mut self, amt: usize) {
+ debug_assert!(self.start < self.end || self.end == 0);
+
+ debug_assert!(amt <= (self.end - self.start));
- if buffered {
- ret.copy_from_slice(&self.buf[..n]);
+ self.start += amt;
+ if self.start >= self.end {
+ self.start = 0;
+ self.end = 0;
}
- Ok(n)
+ info!("consumed {}, {}..{}", amt, self.start, self.end);
}
}
--
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