add first time provider trait

src/time.rs

@@ -1 +1,39 @@
-trait CcsdsTimeProvider {}
+enum CcsdsTimeCodes {
+    None = 0,
+    CucCcsdsEpoch = 0b001,
+    CucAgencyEpoch = 0b010,
+    Cds = 0b100,
+    Ccs = 0b101
+}
+
+/// Trait for generic CCSDS time providers
+trait CcsdsTimeProvider {
+    fn write_to_bytes(&self, bytes: impl AsMut<u8>);
+    /// Returns the pfield of the time provider. The pfield can have one or two bytes depending
+    /// on the extension bit (first bit). The time provider should returns a tuple where the first
+    /// entry denotes the length of the pfield and the second entry is the value of the pfield
+    /// in big endian format.
+    fn pfield(&self) -> (usize, u16);
+    fn ccdsd_time_code(&self) -> CcsdsTimeCodes;
+    fn as_unix_seconds(&self) -> u64;
+}
+
+struct CdsShortTimeProvider {}
+
+impl CcsdsTimeProvider for CdsShortTimeProvider {
+    fn write_to_bytes(&self, bytes: impl AsMut<u8>) {
+        todo!()
+    }
+
+    fn pfield(&self) -> (usize, u16) {
+        todo!()
+    }
+
+    fn ccdsd_time_code(&self) -> CcsdsTimeCodes {
+        todo!()
+    }
+
+    fn as_unix_seconds(&self) -> u64 {
+        todo!()
+    }
+}