Better Circular DMA support

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Breaking changes
+
+- Replace DMA buffer types with `Deref` ans `Unpin`
+
 ## [v0.6.1] - 2020-06-25
 
 ### Added

Cargo.toml

@@ -34,6 +34,10 @@ version = "0.2.2"
 version = "0.2.3"
 features = ["unproven"]
 
+[dependencies.stable_deref_trait]
+default-features = false
+version = "1.1"
+
 [dependencies.stm32-usbd]
 version = "0.5.0"
 features = ["ram_access_1x16"]

examples/adc-dma-circ.rs

@@ -38,7 +38,7 @@ fn main() -> ! {
     let adc_dma = adc1.with_dma(adc_ch0, dma_ch1);
     let buf = singleton!(: [[u16; 8]; 2] = [[0; 8]; 2]).unwrap();
 
-    let mut circ_buffer = adc_dma.circ_read(buf);
+    let mut circ_buffer = adc_dma.circ_double_read(buf);
 
     while circ_buffer.readable_half().unwrap() != Half::First {}
 

examples/serial-dma-circ-len.rs

@@ -0,0 +1,99 @@
+//! Serial interface circular DMA RX transfer test
+
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use panic_semihosting as _;
+
+use cortex_m::singleton;
+use cortex_m_semihosting::{hprint, hprintln};
+
+use cortex_m_rt::entry;
+use stm32f1xx_hal::{
+    dma::CircReadDmaLen,
+    pac,
+    prelude::*,
+    serial::{Config, Serial},
+};
+
+#[entry]
+fn main() -> ! {
+    let p = pac::Peripherals::take().unwrap();
+
+    let mut flash = p.FLASH.constrain();
+    let mut rcc = p.RCC.constrain();
+
+    let clocks = rcc.cfgr.freeze(&mut flash.acr);
+
+    let mut afio = p.AFIO.constrain(&mut rcc.apb2);
+    let channels = p.DMA1.split(&mut rcc.ahb);
+
+    let mut gpioa = p.GPIOA.split(&mut rcc.apb2);
+    // let mut gpiob = p.GPIOB.split(&mut rcc.apb2);
+
+    // USART1
+    let tx = gpioa.pa9.into_alternate_push_pull(&mut gpioa.crh);
+    let rx = gpioa.pa10;
+
+    // USART1
+    // let tx = gpiob.pb6.into_alternate_push_pull(&mut gpiob.crl);
+    // let rx = gpiob.pb7;
+
+    // USART2
+    // let tx = gpioa.pa2.into_alternate_push_pull(&mut gpioa.crl);
+    // let rx = gpioa.pa3;
+
+    // USART3
+    // let tx = gpiob.pb10.into_alternate_push_pull(&mut gpiob.crh);
+    // let rx = gpiob.pb11;
+
+    let serial = Serial::usart1(
+        p.USART1,
+        (tx, rx),
+        &mut afio.mapr,
+        Config::default().baudrate(9_600.bps()),
+        clocks,
+        &mut rcc.apb2,
+    );
+
+    hprintln!("waiting for 5 bytes").unwrap();
+
+    let rx = serial.split().1.with_dma(channels.5);
+    // increase to reasonable size (e.g. 64, 128 etc.) for actual applications
+    let buf = singleton!(: [u8; 8] = [0; 8]).unwrap();
+
+    let mut circ_buffer = rx.circ_read_len(buf);
+
+    // wait until we have 5 bytes
+    while circ_buffer.len() < 5 {}
+
+    let mut dat = [0 as u8; 4];
+    assert!(circ_buffer.read(&mut dat[..]) == 4);
+
+    hprintln!("[{}, {}, {}, {}]", dat[0], dat[1], dat[2], dat[3]).unwrap();
+
+    // try to read again, now only one byte is returned
+    hprintln!("read {}", circ_buffer.read(&mut dat)).unwrap();
+
+    hprintln!("[{}]", dat[0]).unwrap();
+
+    // wait for the buffer to have 4 bytes again
+    while circ_buffer.len() < 4 {}
+
+    // all four bytes should be read in one go
+    assert!(circ_buffer.read(&mut dat) == 4);
+
+    hprintln!("[{}, {}, {}, {}]", dat[0], dat[1], dat[2], dat[3]).unwrap();
+
+    loop {
+        let read = circ_buffer.read(&mut dat);
+
+        if read > 0 {
+            for c in &dat[..read] {
+                hprint!("{}", *c as char).unwrap();
+            }
+            hprintln!("").unwrap();
+        }
+    }
+}

examples/serial-dma-circ.rs

@@ -59,7 +59,7 @@ fn main() -> ! {
     let rx = serial.split().1.with_dma(channels.5);
     let buf = singleton!(: [[u8; 8]; 2] = [[0; 8]; 2]).unwrap();
 
-    let mut circ_buffer = rx.circ_read(buf);
+    let mut circ_buffer = rx.circ_double_read(buf);
 
     while circ_buffer.readable_half().unwrap() != Half::First {}
 

src/adc.rs

@@ -3,7 +3,7 @@
 use core::marker::PhantomData;
 use embedded_hal::adc::{Channel, OneShot};
 
-use crate::dma::{dma1::C1, CircBuffer, Receive, RxDma, Transfer, TransferPayload, W};
+use crate::dma::{dma1::C1, CircDoubleBuffer, Receive, RxDma, Transfer, TransferPayload, W};
 use crate::gpio::Analog;
 use crate::gpio::{gpioa, gpiob, gpioc};
 use crate::rcc::{Clocks, Enable, Reset, APB2};
@@ -667,12 +667,12 @@ where
     }
 }
 
-impl<B, PINS, MODE> crate::dma::CircReadDma<B, u16> for AdcDma<PINS, MODE>
+impl<B, PINS, MODE> crate::dma::CircDoubleReadDma<B, u16> for AdcDma<PINS, MODE>
 where
     Self: TransferPayload,
     B: as_slice::AsMutSlice<Element = u16>,
 {
-    fn circ_read(mut self, buffer: &'static mut [B; 2]) -> CircBuffer<B, Self> {
+    fn circ_double_read(mut self, buffer: &'static mut [B; 2]) -> CircDoubleBuffer<B, Self> {
         {
             let buffer = buffer[0].as_mut_slice();
             self.channel
@@ -701,7 +701,7 @@ where
 
         self.start();
 
-        CircBuffer::new(buffer, self)
+        CircDoubleBuffer::new(buffer, self)
     }
 }