proto fw: handle ring buffer

src/libboard_artiq/src/cxp_proto.rs

@@ -22,19 +22,6 @@ pub enum Error {
     UnknownPacket(u8),
 }
 
-#[derive(Debug)]
-pub enum CtrlError {
-    AddressReadOnly,
-    AddressWriteOnly,
-    CRCFailed,
-    DataSizeDifferent,
-    InvalidAddress,
-    InvalidData,
-    InvalidOpcode,
-    MalformedPacket,
-    SizeToolarge,
-}
-
 impl From<IoError> for Error {
     fn from(_: IoError) -> Error {
         Error::BufferError
@@ -137,17 +124,25 @@ impl DownConnPacket {
     }
 }
 
-pub fn receive(channel: usize) -> Result<(), Error> {
+pub fn receive(channel: usize) -> Result<Option<DownConnPacket>, Error> {
     unsafe {
-        let ptr = CXP_RX_MEM[channel].base as *mut u32;
-        let mut reader = Cursor::new(slice::from_raw_parts_mut(ptr as *mut u8, MEM_LEN));
+        if (CXP[channel].downconn_pending_packet_read)() == 1 {
+            let read_buffer_ptr = (CXP[channel].downconn_read_ptr_read)() as usize;
+            println!("buffer ptr = {}", read_buffer_ptr);
+            let ptr = (CXP_RX_MEM[channel].base + read_buffer_ptr * MEM_LEN) as *mut u8;
+
+            let mut reader = Cursor::new(slice::from_raw_parts_mut(ptr, MEM_LEN));
             let packet_type = (CXP[channel].downconn_packet_type_read)();
 
             let packet = DownConnPacket::read_from(&mut reader, packet_type);
-
             println!("{:?}", packet);
+
+            (CXP[channel].downconn_pending_packet_write)(1);
+            Ok(Some(packet?))
+        } else {
+            Ok(None)
+        }
     }
-    Ok(())
 }
 
 trait CxpWrite {
@@ -405,8 +400,9 @@ pub fn downconn_debug_send(channel: usize, packet: &UpConnPacket) -> Result<(),
 
 pub fn downconn_debug_mem_print(channel: usize) {
     unsafe {
-        let ptr = CXP_RX_MEM[channel].base as *mut u32;
-        print_packet(slice::from_raw_parts_mut(ptr as *mut u8, MEM_LEN));
+        let ptr = CXP_RX_MEM[channel].base as *mut u8;
+        let arr = slice::from_raw_parts_mut(ptr, MEM_LEN * 4);
+        print_packet(arr);
     }
 }