CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   file data field as a mutable slice. This allows to read data from the virtual file system
   API to the file data buffer without an intermediate buffer.
 - Generic `EofPdu::new` constructor.
+- Added generic sequence counter module.
 
 ## Added and Changed
 

Cargo.toml

@@ -15,6 +15,7 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 [dependencies]
 crc = "3"
 delegate = ">=0.8, <0.13"
+paste = "1"
 
 [dependencies.zerocopy]
 version = "0.7"

src/lib.rs

@@ -76,6 +76,7 @@ use serde::{Deserialize, Serialize};
 
 pub mod cfdp;
 pub mod ecss;
+pub mod seq_count;
 pub mod time;
 pub mod util;
 

src/seq_count.rs

@@ -0,0 +1,250 @@
+use crate::MAX_SEQ_COUNT;
+use core::cell::Cell;
+use paste::paste;
+#[cfg(feature = "std")]
+pub use stdmod::*;
+
+/// Core trait for objects which can provide a sequence count.
+///
+/// The core functions are not mutable on purpose to allow easier usage with
+/// static structs when using the interior mutability pattern. This can be achieved by using
+/// [Cell], [core::cell::RefCell] or atomic types.
+pub trait SequenceCountProvider {
+    type Raw: Into<u64>;
+    const MAX_BIT_WIDTH: usize;
+
+    fn get(&self) -> Self::Raw;
+
+    fn increment(&self);
+
+    fn get_and_increment(&self) -> Self::Raw {
+        let val = self.get();
+        self.increment();
+        val
+    }
+}
+
+#[derive(Clone)]
+pub struct SeqCountProviderSimple<T: Copy> {
+    seq_count: Cell<T>,
+    max_val: T,
+}
+
+macro_rules! impl_for_primitives {
+    ($($ty: ident,)+) => {
+        $(
+            paste! {
+                impl SeqCountProviderSimple<$ty> {
+                    pub fn [<new_custom_max_val_ $ty>](max_val: $ty) -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val,
+                        }
+                    }
+                    pub fn [<new_ $ty>]() -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val: $ty::MAX
+                        }
+                    }
+                }
+
+                impl Default for SeqCountProviderSimple<$ty> {
+                    fn default() -> Self {
+                        Self::[<new_ $ty>]()
+                    }
+                }
+
+                impl SequenceCountProvider for SeqCountProviderSimple<$ty> {
+                    type Raw = $ty;
+                    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                    fn get(&self) -> Self::Raw {
+                        self.seq_count.get()
+                    }
+
+                    fn increment(&self) {
+                        self.get_and_increment();
+                    }
+
+                    fn get_and_increment(&self) -> Self::Raw {
+                        let curr_count = self.seq_count.get();
+
+                        if curr_count == self.max_val {
+                            self.seq_count.set(0);
+                        } else {
+                            self.seq_count.set(curr_count + 1);
+                        }
+                        curr_count
+                    }
+                }
+            }
+        )+
+    }
+}
+
+impl_for_primitives!(u8, u16, u32, u64,);
+
+/// This is a sequence count provider which wraps around at [MAX_SEQ_COUNT].
+#[derive(Clone)]
+pub struct CcsdsSimpleSeqCountProvider {
+    provider: SeqCountProviderSimple<u16>,
+}
+
+impl Default for CcsdsSimpleSeqCountProvider {
+    fn default() -> Self {
+        Self {
+            provider: SeqCountProviderSimple::new_custom_max_val_u16(MAX_SEQ_COUNT),
+        }
+    }
+}
+
+impl SequenceCountProvider for CcsdsSimpleSeqCountProvider {
+    type Raw = u16;
+    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+    delegate::delegate! {
+        to self.provider {
+            fn get(&self) -> u16;
+            fn increment(&self);
+            fn get_and_increment(&self) -> u16;
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+pub mod stdmod {
+    use super::*;
+    use std::sync::{Arc, Mutex};
+
+    macro_rules! sync_clonable_seq_counter_impl {
+         ($($ty: ident,)+) => {
+             $(paste! {
+                 /// These sequence counters can be shared between threads and can also be
+                 /// configured to wrap around at specified maximum values. Please note that
+                 /// that the API provided by this class will not panic und [Mutex] lock errors,
+                 /// but it will yield 0 for the getter functions.
+                 #[derive(Clone, Default)]
+                 pub struct [<SeqCountProviderSync $ty:upper>] {
+                     seq_count: Arc<Mutex<$ty>>,
+                     max_val: $ty
+                 }
+
+                 impl [<SeqCountProviderSync $ty:upper>] {
+                     pub fn new() -> Self {
+                        Self::new_with_max_val($ty::MAX)
+                     }
+
+                     pub fn new_with_max_val(max_val: $ty) -> Self {
+                         Self {
+                             seq_count: Arc::default(),
+                             max_val
+                         }
+                     }
+                 }
+                 impl SequenceCountProvider for [<SeqCountProviderSync $ty:upper>] {
+                    type Raw = $ty;
+                    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                    fn get(&self) -> $ty {
+                        match self.seq_count.lock() {
+                            Ok(counter) => *counter,
+                            Err(_) => 0
+                        }
+                    }
+
+                    fn increment(&self) {
+                        self.get_and_increment();
+                    }
+
+                    fn get_and_increment(&self) -> $ty {
+                        match self.seq_count.lock() {
+                            Ok(mut counter) => {
+                                let val = *counter;
+                                if val == self.max_val {
+                                    *counter = 0;
+                                } else {
+                                    *counter += 1;
+                                }
+                                val
+                            }
+                            Err(_) => 0,
+                        }
+                    }
+                 }
+             })+
+         }
+    }
+    sync_clonable_seq_counter_impl!(u8, u16, u32, u64,);
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::seq_count::{
+        CcsdsSimpleSeqCountProvider, SeqCountProviderSimple, SeqCountProviderSyncU8,
+        SequenceCountProvider,
+    };
+    use crate::MAX_SEQ_COUNT;
+
+    #[test]
+    fn test_u8_counter() {
+        let u8_counter = SeqCountProviderSimple::<u8>::default();
+        assert_eq!(u8_counter.get(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 1);
+        assert_eq!(u8_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_u8_counter_overflow() {
+        let u8_counter = SeqCountProviderSimple::new_u8();
+        for _ in 0..256 {
+            u8_counter.increment();
+        }
+        assert_eq!(u8_counter.get(), 0);
+    }
+
+    #[test]
+    fn test_ccsds_counter() {
+        let ccsds_counter = CcsdsSimpleSeqCountProvider::default();
+        assert_eq!(ccsds_counter.get(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 1);
+        assert_eq!(ccsds_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_ccsds_counter_overflow() {
+        let ccsds_counter = CcsdsSimpleSeqCountProvider::default();
+        for _ in 0..MAX_SEQ_COUNT + 1 {
+            ccsds_counter.increment();
+        }
+        assert_eq!(ccsds_counter.get(), 0);
+    }
+
+    #[test]
+    fn test_atomic_ref_counters() {
+        let sync_u8_counter = SeqCountProviderSyncU8::new();
+        assert_eq!(sync_u8_counter.get(), 0);
+        assert_eq!(sync_u8_counter.get_and_increment(), 0);
+        assert_eq!(sync_u8_counter.get_and_increment(), 1);
+        assert_eq!(sync_u8_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_atomic_ref_counters_overflow() {
+        let sync_u8_counter = SeqCountProviderSyncU8::new();
+        for _ in 0..u8::MAX as u16 + 1 {
+            sync_u8_counter.increment();
+        }
+        assert_eq!(sync_u8_counter.get(), 0);
+    }
+
+    #[test]
+    fn test_atomic_ref_counters_overflow_custom_max_val() {
+        let sync_u8_counter = SeqCountProviderSyncU8::new_with_max_val(128);
+        for _ in 0..129 {
+            sync_u8_counter.increment();
+        }
+        assert_eq!(sync_u8_counter.get(), 0);
+    }
+}