add: calc which header terminations are needed

dot15d4/src/frame/mod.rs

@@ -367,11 +367,15 @@ impl<T: AsRef<[u8]> + AsMut<[u8]>> Frame<T> {
     }
 
     /// Set the Information Elements field values in the buffer, based on the given _.
-    pub fn set_information_elements(&mut self, ie: &InformationElementsRepr) {
+    pub fn set_information_elements(
+        &mut self,
+        ie: &InformationElementsRepr,
+        contains_payload: bool,
+    ) {
         let mut offset = 2;
         offset += (!self.frame_control().sequence_number_suppression() as usize);
         offset += self.addressing().len(&self.frame_control());
-        ie.emit(&mut self.buffer.as_mut()[offset..]);
+        ie.emit(&mut self.buffer.as_mut()[offset..], contains_payload);
     }
 
     /// Set the payload of the frame.

dot15d4/src/frame/repr/ie/mod.rs

@@ -40,42 +40,95 @@ impl InformationElementsRepr {
         }
     }
 
+    /// The header terminations required to emit the Information Elements.
+    /// The first bool is the HT1, the second is the HT2, and the third is the PT.
+    fn header_terminations(&self, contains_payload: bool) -> (bool, bool, bool) {
+        match (
+            !self.header_information_elements.is_empty(),
+            !self.payload_information_elements.is_empty(),
+            contains_payload,
+        ) {
+            // No IE lists, so no terminations.
+            (false, false, false) => (false, false, false),
+            // Only header IE list. The end of the frame can be determined by the length of the
+            // frame.
+            (true, false, false) => (false, false, false),
+            // Only payload IE list. The HT1 is required to terminate the header IE list.
+            (false, true, false) => (true, false, false),
+            // Both IE lists. The HT1 is required to terminate the header IE list.
+            // The payload HT is optional.
+            (true, true, false) => (true, false, false),
+            // No IE lists, so no terminations.
+            (false, false, true) => (false, false, false),
+            // No payload IE list. The HT2 is required to terminate the header IE list.
+            (true, false, true) => (false, true, false),
+            // No header IE list. The HT1 is required to terminate the payload IE list.
+            // The payload HT is optional.
+            (false, true, true) => (true, false, true),
+            // Both IE lists. The HT1 is required to terminate the header IE list.
+            // The payload HT is optional.
+            (true, true, true) => (true, false, true),
+        }
+    }
+
     /// The buffer length required to emit the Information Elements.
-    pub fn buffer_len(&self) -> usize {
+    pub fn buffer_len(&self, contains_payload: bool) -> usize {
         let mut len = 0;
 
+        let (ht1, ht2, pt) = self.header_terminations(contains_payload);
+
         for ie in self.header_information_elements.iter() {
             len += ie.buffer_len();
         }
 
-        if !self.payload_information_elements.is_empty() {
+        if ht1 {
+            len += HeaderInformationElementRepr::HeaderTermination1.buffer_len();
+        }
+
+        if ht2 {
             len += HeaderInformationElementRepr::HeaderTermination1.buffer_len();
         }
 
         for ie in self.payload_information_elements.iter() {
             len += ie.buffer_len();
         }
 
+        if pt {
+            len += PayloadInformationElementRepr::PayloadTermination.buffer_len();
+        }
+
         len
     }
 
     /// Emit the Information Elements into a buffer.
-    pub fn emit(&self, buffer: &mut [u8]) {
+    pub fn emit(&self, buffer: &mut [u8], contains_payload: bool) {
         let mut offset = 0;
 
+        let (ht1, ht2, pt) = self.header_terminations(contains_payload);
+
         for ie in self.header_information_elements.iter() {
             ie.emit(&mut buffer[offset..][..ie.buffer_len()]);
             offset += ie.buffer_len();
         }
 
-        if !self.payload_information_elements.is_empty() {
+        if ht1 {
             HeaderInformationElementRepr::HeaderTermination1.emit(&mut buffer[offset..][..2]);
             offset += 2;
         }
 
+        if ht2 {
+            HeaderInformationElementRepr::HeaderTermination2.emit(&mut buffer[offset..][..2]);
+            offset += 2;
+        }
+
         for ie in self.payload_information_elements.iter() {
             ie.emit(&mut buffer[offset..][..ie.buffer_len()]);
             offset += ie.buffer_len();
         }
+
+        if pt {
+            PayloadInformationElementRepr::PayloadTermination.emit(&mut buffer[offset..][..2]);
+            offset += 2;
+        }
     }
 }

dot15d4/src/frame/repr/ie/payloads.rs

@@ -8,6 +8,7 @@ use heapless::Vec;
 #[derive(Debug)]
 pub enum PayloadInformationElementRepr {
     Mlme(Vec<NestedInformationElementRepr, 16>),
+    PayloadTermination,
 }
 
 impl PayloadInformationElementRepr {
@@ -44,6 +45,7 @@ impl PayloadInformationElementRepr {
 
                 len
             }
+            Self::PayloadTermination => 0,
         }
     }
 
@@ -63,6 +65,7 @@ impl PayloadInformationElementRepr {
                     offset += ie.buffer_len();
                 }
             }
+            Self::PayloadTermination => todo!(),
         }
     }
 }
@@ -72,6 +75,7 @@ impl From<&PayloadInformationElementRepr> for PayloadGroupId {
         use PayloadInformationElementRepr::*;
         match val {
             Mlme(_) => PayloadGroupId::Mlme,
+            PayloadTermination => PayloadGroupId::PayloadTermination,
         }
     }
 }

dot15d4/src/frame/repr/mod.rs

@@ -54,7 +54,7 @@ impl<'f> FrameRepr<'f> {
         len += self.addressing_fields.buffer_len(&self.frame_control);
 
         if let Some(ie) = &self.information_elements {
-            len += ie.buffer_len();
+            len += ie.buffer_len(self.payload.is_some());
         }
 
         if let Some(payload) = self.payload {
@@ -74,7 +74,7 @@ impl<'f> FrameRepr<'f> {
         frame.set_addressing_fields(&self.addressing_fields);
 
         if let Some(ie) = &self.information_elements {
-            frame.set_information_elements(ie);
+            frame.set_information_elements(ie, self.payload.is_some());
         }
 
         if let Some(payload) = self.payload {