nrf/buffered_uart: refactor so rx/tx halves are independent.

1 files changed, 30 insertions, 3 deletions

diff --git a/embassy-hal-internal/src/atomic_ring_buffer.rs b/embassy-hal-internal/src/atomic_ring_buffer.rs
index b4f2cec28..34ceac852 100644
--- a/embassy-hal-internal/src/atomic_ring_buffer.rs
+++ b/embassy-hal-internal/src/atomic_ring_buffer.rs
@@ -1,6 +1,6 @@
 //! Atomic reusable ringbuffer.
-use core::slice;
 use core::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
+use core::{ptr, slice};
 
 /// Atomic reusable ringbuffer
 ///
@@ -73,6 +73,7 @@ impl RingBuffer {
     pub unsafe fn deinit(&self) {
         // Ordering: it's OK to use `Relaxed` because this is not called
         // concurrently with other methods.
+        self.buf.store(ptr::null_mut(), Ordering::Relaxed);
         self.len.store(0, Ordering::Relaxed);
         self.start.store(0, Ordering::Relaxed);
         self.end.store(0, Ordering::Relaxed);
@@ -82,20 +83,46 @@ impl RingBuffer {
     ///
     /// # Safety
     ///
-    /// Only one reader can exist at a time.
+    /// - Only one reader can exist at a time.
+    /// - Ringbuffer must be initialized.
     pub unsafe fn reader(&self) -> Reader<'_> {
         Reader(self)
     }
 
+    /// Try creating a reader, fails if not initialized.
+    ///
+    /// # Safety
+    ///
+    /// Only one reader can exist at a time.
+    pub unsafe fn try_reader(&self) -> Option<Reader<'_>> {
+        if self.buf.load(Ordering::Relaxed).is_null() {
+            return None;
+        }
+        Some(Reader(self))
+    }
+
     /// Create a writer.
     ///
     /// # Safety
     ///
-    /// Only one writer can exist at a time.
+    /// - Only one writer can exist at a time.
+    /// - Ringbuffer must be initialized.
     pub unsafe fn writer(&self) -> Writer<'_> {
         Writer(self)
     }
 
+    /// Try creating a writer, fails if not initialized.
+    ///
+    /// # Safety
+    ///
+    /// Only one writer can exist at a time.
+    pub unsafe fn try_writer(&self) -> Option<Writer<'_>> {
+        if self.buf.load(Ordering::Relaxed).is_null() {
+            return None;
+        }
+        Some(Writer(self))
+    }
+
     /// Return length of buffer.
     pub fn len(&self) -> usize {
         self.len.load(Ordering::Relaxed)