From a76f650c465edc33142121504e8aab58c5aa3622 Mon Sep 17 00:00:00 2001
From: Emil Fresk <emil.fresk@gmail.com>
Date: Thu, 15 Feb 2024 15:43:25 +0100
Subject: [PATCH] Started

---
 rtic-sync/Cargo.toml         |  1 +
 rtic-sync/src/bit_channel.rs | 89 ++++++++++++++++++++++++++++++++++++
 rtic-sync/src/lib.rs         |  3 +-
 3 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 rtic-sync/src/bit_channel.rs

diff --git a/rtic-sync/Cargo.toml b/rtic-sync/Cargo.toml
index 7df193d1e3..234a051df2 100644
--- a/rtic-sync/Cargo.toml
+++ b/rtic-sync/Cargo.toml
@@ -28,6 +28,7 @@ portable-atomic = { version = "1", default-features = false }
 embedded-hal = { version = "1.0", optional = true }
 embedded-hal-async = { version = "1.0", optional = true }
 embedded-hal-bus = { version = "0.1.0", optional = true, features = ["async"] }
+bitflags = "2"
 
 [dev-dependencies]
 tokio = { version = "1", features = ["rt", "macros", "time"] }
diff --git a/rtic-sync/src/bit_channel.rs b/rtic-sync/src/bit_channel.rs
new file mode 100644
index 0000000000..703d351a64
--- /dev/null
+++ b/rtic-sync/src/bit_channel.rs
@@ -0,0 +1,89 @@
+//! A channel operating on bitflags.
+
+use bitflags::{Bits, Flags};
+use core::sync::atomic::{AtomicU16, AtomicU8, Ordering};
+
+//
+// Bit channel
+//
+
+pub struct BitChannel<T: Flags>
+where
+    T: Flags,
+    T::Bits: AtomicType,
+{
+    atomic: <T::Bits as AtomicType>::Atomic,
+}
+
+impl<T> BitChannel<T>
+where
+    T: Flags,
+    T::Bits: AtomicType,
+{
+    pub const fn new() -> Self {
+        BitChannel {
+            atomic: T::Bits::ATOMIC_ZERO,
+        }
+    }
+
+    pub fn test(&self) {
+        T::Bits::fetch_and(&self.atomic, T::Bits::EMPTY, Ordering::Relaxed);
+    }
+}
+
+pub trait AtomicType: Sized {
+    type Atomic: From<Self>;
+    
+    const ATOMIC_ZERO: Self::Atomic;
+
+    fn fetch_and(a: &Self::Atomic, b: Self, order: Ordering) -> Self;
+}
+
+impl AtomicType for u16 {
+    type Atomic = AtomicU16;
+    
+    const ATOMIC_ZERO: Self::Atomic = AtomicU16::new(0);
+
+    fn fetch_and(a: &Self::Atomic, b: Self, order: Ordering) -> Self {
+        a.fetch_and(b, order)
+    }
+}
+
+impl AtomicType for u8 {
+    type Atomic = AtomicU8;
+
+    const ATOMIC_ZERO: Self::Atomic = AtomicU8::new(0);
+
+    fn fetch_and(a: &Self::Atomic, b: Self, order: Ordering) -> Self {
+        a.fetch_and(b, order)
+    }
+}
+
+// etc...
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use bitflags::bitflags;
+
+    bitflags! {
+        struct FlagsU8: u8 {
+            const A = 1;
+            const B = 2;
+        }
+    }
+
+    bitflags! {
+        struct FlagsU16: u16 {
+            const A = 1;
+            const B = 2;
+        }
+    }
+
+    #[test]
+    fn test() {
+        let a = BitChannel::<FlagsU8>::new();
+        let b = BitChannel::<FlagsU16>::new();
+    }
+}
+
diff --git a/rtic-sync/src/lib.rs b/rtic-sync/src/lib.rs
index ecd3247d5a..ba30f69a92 100644
--- a/rtic-sync/src/lib.rs
+++ b/rtic-sync/src/lib.rs
@@ -1,9 +1,10 @@
 //! Synchronization primitives for asynchronous contexts.
 
 #![no_std]
-#![deny(missing_docs)]
+#![warn(missing_docs)]
 
 pub mod arbiter;
+pub mod bit_channel;
 pub mod channel;
 pub use portable_atomic;