Re-structure sat-rs

- Add new shared subcrate satrs-shared to split off some shared
  components not expected to change very often.
- Renmame `satrs-core` to `satrs`. It is expected that sat-rs will remain
  the primary crate, so the core information is superfluous, and core also
  implies stability, which will not be the case for some time.

satrs/src/tmtc/mod.rs

@@ -0,0 +1,117 @@
+//! Telemetry and Telecommanding (TMTC) module. Contains packet routing components with special
+//! support for CCSDS and ECSS packets.
+//!
+//! The distributor modules provided by this module use trait objects provided by the user to
+//! directly dispatch received packets to packet listeners based on packet fields like the CCSDS
+//! Application Process ID (APID) or the ECSS PUS service type. This allows for fast packet
+//! routing without the overhead and complication of using message queues. However, it also requires
+#[cfg(feature = "alloc")]
+use downcast_rs::{impl_downcast, Downcast};
+use spacepackets::SpHeader;
+
+#[cfg(feature = "alloc")]
+pub mod ccsds_distrib;
+#[cfg(feature = "alloc")]
+pub mod pus_distrib;
+pub mod tm_helper;
+
+#[cfg(feature = "alloc")]
+pub use ccsds_distrib::{CcsdsDistributor, CcsdsError, CcsdsPacketHandler};
+#[cfg(feature = "alloc")]
+pub use pus_distrib::{PusDistributor, PusServiceProvider};
+
+pub type TargetId = u32;
+
+/// Generic trait for object which can receive any telecommands in form of a raw bytestream, with
+/// no assumptions about the received protocol.
+///
+/// This trait is implemented by both the [crate::tmtc::pus_distrib::PusDistributor] and the
+/// [crate::tmtc::ccsds_distrib::CcsdsDistributor]  which allows to pass the respective packets in
+/// raw byte format into them.
+pub trait ReceivesTcCore {
+    type Error;
+    fn pass_tc(&mut self, tc_raw: &[u8]) -> Result<(), Self::Error>;
+}
+
+/// Extension trait of [ReceivesTcCore] which allows downcasting by implementing [Downcast] and
+/// is also sendable.
+#[cfg(feature = "alloc")]
+pub trait ReceivesTc: ReceivesTcCore + Downcast + Send {
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast(&self) -> &dyn ReceivesTcCore<Error = Self::Error>;
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast_mut(&mut self) -> &mut dyn ReceivesTcCore<Error = Self::Error>;
+}
+
+/// Blanket implementation to automatically implement [ReceivesTc] when the [alloc] feature
+/// is enabled.
+#[cfg(feature = "alloc")]
+impl<T> ReceivesTc for T
+where
+    T: ReceivesTcCore + Send + 'static,
+{
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast(&self) -> &dyn ReceivesTcCore<Error = Self::Error> {
+        self
+    }
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast_mut(&mut self) -> &mut dyn ReceivesTcCore<Error = Self::Error> {
+        self
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl_downcast!(ReceivesTc assoc Error);
+
+/// Generic trait for object which can receive CCSDS space packets, for example ECSS PUS packets
+/// for CCSDS File Delivery Protocol (CFDP) packets.
+///
+/// This trait is implemented by both the [crate::tmtc::pus_distrib::PusDistributor] and the
+/// [crate::tmtc::ccsds_distrib::CcsdsDistributor] which allows
+/// to pass the respective packets in raw byte format or in CCSDS format into them.
+pub trait ReceivesCcsdsTc {
+    type Error;
+    fn pass_ccsds(&mut self, header: &SpHeader, tc_raw: &[u8]) -> Result<(), Self::Error>;
+}
+
+/// Generic trait for a TM packet source, with no restrictions on the type of TM.
+/// Implementors write the telemetry into the provided buffer and return the size of the telemetry.
+pub trait TmPacketSourceCore {
+    type Error;
+    fn retrieve_packet(&mut self, buffer: &mut [u8]) -> Result<usize, Self::Error>;
+}
+
+/// Extension trait of [TmPacketSourceCore] which allows downcasting by implementing [Downcast] and
+/// is also sendable.
+#[cfg(feature = "alloc")]
+pub trait TmPacketSource: TmPacketSourceCore + Downcast + Send {
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast(&self) -> &dyn TmPacketSourceCore<Error = Self::Error>;
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast_mut(&mut self) -> &mut dyn TmPacketSourceCore<Error = Self::Error>;
+}
+
+/// Blanket implementation to automatically implement [ReceivesTc] when the [alloc] feature
+/// is enabled.
+#[cfg(feature = "alloc")]
+impl<T> TmPacketSource for T
+where
+    T: TmPacketSourceCore + Send + 'static,
+{
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast(&self) -> &dyn TmPacketSourceCore<Error = Self::Error> {
+        self
+    }
+    // Remove this once trait upcasting coercion has been implemented.
+    // Tracking issue: https://github.com/rust-lang/rust/issues/65991
+    fn upcast_mut(&mut self) -> &mut dyn TmPacketSourceCore<Error = Self::Error> {
+        self
+    }
+}