proto fw: add helper function for 4x writer

src/libboard_artiq/src/cxp_proto.rs

@@ -266,16 +266,48 @@ pub fn receive(channel: usize) -> Result<Option<DownConnPacket>, Error> {
 }
 
 trait CxpWrite {
+    fn write_all_4x(&mut self, buf: &[u8]) -> Result<(), Error>;
+
     fn write_4x_u8(&mut self, value: u8) -> Result<(), Error>;
 
+    fn write_4x_u16(&mut self, value: u16) -> Result<(), Error>;
+
+    fn write_4x_u32(&mut self, value: u32) -> Result<(), Error>;
+
+    fn write_4x_u64(&mut self, value: u64) -> Result<(), Error>;
+
     fn write_u32(&mut self, value: u32) -> Result<(), Error>;
 }
 impl<Cursor: Write> CxpWrite for Cursor {
-    fn write_4x_u8(&mut self, value: u8) -> Result<(), Error> {
+    fn write_all_4x(&mut self, buf: &[u8]) -> Result<(), Error> {
-        self.write_all(&[value; 4])?;
+        for byte in buf {
+            self.write_all(&[*byte; 4])?;
+        }
         Ok(())
     }
 
+    fn write_4x_u8(&mut self, value: u8) -> Result<(), Error> {
+        self.write_all_4x(&[value])
+    }
+
+    fn write_4x_u16(&mut self, value: u16) -> Result<(), Error> {
+        let mut bytes = [0; 2];
+        NetworkEndian::write_u16(&mut bytes, value);
+        self.write_all_4x(&bytes)
+    }
+
+    fn write_4x_u32(&mut self, value: u32) -> Result<(), Error> {
+        let mut bytes = [0; 4];
+        NetworkEndian::write_u32(&mut bytes, value);
+        self.write_all_4x(&bytes)
+    }
+
+    fn write_4x_u64(&mut self, value: u64) -> Result<(), Error> {
+        let mut bytes = [0; 6];
+        NetworkEndian::write_u64(&mut bytes, value);
+        self.write_all_4x(&bytes)
+    }
+
     fn write_u32(&mut self, value: u32) -> Result<(), Error> {
         let mut bytes = [0; 4];
         NetworkEndian::write_u32(&mut bytes, value);
@@ -392,21 +424,11 @@ impl UpConnPacket {
                 timestamp,
                 data,
             } => {
-                let id_bytes = conn_id.to_be_bytes();
-                let length_bytes = length.to_be_bytes();
-
                 // event packet header
                 writer.write_4x_u8(0x07)?;
-
+                writer.write_4x_u32(conn_id)?;
-                writer.write_4x_u8(id_bytes[0])?;
-                writer.write_4x_u8(id_bytes[1])?;
-                writer.write_4x_u8(id_bytes[2])?;
-                writer.write_4x_u8(id_bytes[3])?;
-
                 writer.write_4x_u8(packet_tag)?;
-
+                writer.write_4x_u16(length)?;
-                writer.write_4x_u8(length_bytes[0])?;
-                writer.write_4x_u8(length_bytes[1])?;
 
                 // event message
                 let ev_size = event_size.to_be_bytes();