Add RawRwLock trait and RawRwLockImpl struct implementation

* Implement `RawRwLock` trait with methods for read and write locking
* Implement `RawRwLockImpl` struct with atomic state and waker
* Implement `RawRwLockImpl::lock_read`, `RawRwLockImpl::try_lock_read`, and `RawRwLockImpl::unlock_read` methods
* Implement `RawRwLockImpl::lock_write`, `RawRwLockImpl::try_lock_write`, and `RawRwLockImpl::unlock_write` methods

embassy-sync/src/blocking_mutex/raw_rwlock.rs

@@ -0,0 +1,86 @@
+use core::sync::atomic::{AtomicUsize, Ordering};
+use core::task::Waker;
+use core::cell::UnsafeCell;
+
+pub trait RawRwLock {
+    fn lock_read(&self);
+    fn try_lock_read(&self) -> bool;
+    fn unlock_read(&self);
+    fn lock_write(&self);
+    fn try_lock_write(&self) -> bool;
+    fn unlock_write(&self);
+}
+
+pub struct RawRwLockImpl {
+    state: AtomicUsize,
+    waker: UnsafeCell<Option<Waker>>,
+}
+
+impl RawRwLockImpl {
+    pub const fn new() -> Self {
+        Self {
+            state: AtomicUsize::new(0),
+            waker: UnsafeCell::new(None),
+        }
+    }
+}
+
+unsafe impl Send for RawRwLockImpl {}
+unsafe impl Sync for RawRwLockImpl {}
+
+impl RawRwLock for RawRwLockImpl {
+    fn lock_read(&self) {
+        loop {
+            let state = self.state.load(Ordering::Acquire);
+            if state & 1 == 0 {
+                if self.state.compare_and_swap(state, state + 2, Ordering::AcqRel) == state {
+                    break;
+                }
+            }
+        }
+    }
+
+    fn try_lock_read(&self) -> bool {
+        let state = self.state.load(Ordering::Acquire);
+        if state & 1 == 0 {
+            if self.state.compare_and_swap(state, state + 2, Ordering::AcqRel) == state {
+                return true;
+            }
+        }
+        false
+    }
+
+    fn unlock_read(&self) {
+        self.state.fetch_sub(2, Ordering::Release);
+        if self.state.load(Ordering::Acquire) == 0 {
+            if let Some(waker) = unsafe { &*self.waker.get() } {
+                waker.wake_by_ref();
+            }
+        }
+    }
+
+    fn lock_write(&self) {
+        loop {
+            let state = self.state.load(Ordering::Acquire);
+            if state == 0 {
+                if self.state.compare_and_swap(0, 1, Ordering::AcqRel) == 0 {
+                    break;
+                }
+            }
+        }
+    }
+
+    fn try_lock_write(&self) -> bool {
+        if self.state.compare_and_swap(0, 1, Ordering::AcqRel) == 0 {
+            return true;
+        }
+        false
+    }
+
+    fn unlock_write(&self) {
+        self.state.store(0, Ordering::Release);
+        if let Some(waker) = unsafe { &*self.waker.get() } {
+            waker.wake_by_ref();
+        }
+    }
+}

embassy-sync/src/raw_rwlock.rs

@@ -1,86 +0,0 @@
-use core::sync::atomic::{AtomicUsize, Ordering};
-use core::task::Waker;
-use core::cell::UnsafeCell;
-
-pub trait RawRwLock {
-    fn lock_read(&self);
-    fn try_lock_read(&self) -> bool;
-    fn unlock_read(&self);
-    fn lock_write(&self);
-    fn try_lock_write(&self) -> bool;
-    fn unlock_write(&self);
-}
-
-pub struct RawRwLockImpl {
-    state: AtomicUsize,
-    waker: UnsafeCell<Option<Waker>>,
-}
-
-impl RawRwLockImpl {
-    pub const fn new() -> Self {
-        Self {
-            state: AtomicUsize::new(0),
-            waker: UnsafeCell::new(None),
-        }
-    }
-}
-
-unsafe impl Send for RawRwLockImpl {}
-unsafe impl Sync for RawRwLockImpl {}
-
-impl RawRwLock for RawRwLockImpl {
-    fn lock_read(&self) {
-        loop {
-            let state = self.state.load(Ordering::Acquire);
-            if state & 1 == 0 {
-                if self.state.compare_and_swap(state, state + 2, Ordering::AcqRel) == state {
-                    break;
-                }
-            }
-        }
-    }
-
-    fn try_lock_read(&self) -> bool {
-        let state = self.state.load(Ordering::Acquire);
-        if state & 1 == 0 {
-            if self.state.compare_and_swap(state, state + 2, Ordering::AcqRel) == state {
-                return true;
-            }
-        }
-        false
-    }
-
-    fn unlock_read(&self) {
-        self.state.fetch_sub(2, Ordering::Release);
-        if self.state.load(Ordering::Acquire) == 0 {
-            if let Some(waker) = unsafe { &*self.waker.get() } {
-                waker.wake_by_ref();
-            }
-        }
-    }
-
-    fn lock_write(&self) {
-        loop {
-            let state = self.state.load(Ordering::Acquire);
-            if state == 0 {
-                if self.state.compare_and_swap(0, 1, Ordering::AcqRel) == 0 {
-                    break;
-                }
-            }
-        }
-    }
-
-    fn try_lock_write(&self) -> bool {
-        if self.state.compare_and_swap(0, 1, Ordering::AcqRel) == 0 {
-            return true;
-        }
-        false
-    }
-
-    fn unlock_write(&self) {
-        self.state.store(0, Ordering::Release);
-        if let Some(waker) = unsafe { &*self.waker.get() } {
-            waker.wake_by_ref();
-        }
-    }
-}