From 6b19bf09e2638e8efd5baeaf95ef1f6f2fd0220a Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Thu, 30 Apr 2015 12:30:13 +0300
Subject: [PATCH] Support for priority in TransferSender

---
 .../uavcan/transport/transfer_sender.hpp      | 25 ++++++++++++++++---
 libuavcan/src/transport/uc_frame.cpp          |  1 +
 .../src/transport/uc_transfer_sender.cpp      | 15 ++++++++---
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/libuavcan/include/uavcan/transport/transfer_sender.hpp b/libuavcan/include/uavcan/transport/transfer_sender.hpp
index b67edf23a7..26d6e0e628 100644
--- a/libuavcan/include/uavcan/transport/transfer_sender.hpp
+++ b/libuavcan/include/uavcan/transport/transfer_sender.hpp
@@ -21,6 +21,7 @@ class UAVCAN_EXPORT TransferSender
 {
     const MonotonicDuration max_transfer_interval_;
     const DataTypeDescriptor& data_type_;
+    TransferPriority priority_;
     const CanTxQueue::Qos qos_;
     const TransferCRC crc_base_;
     CanIOFlags flags_;
@@ -29,7 +30,7 @@ class UAVCAN_EXPORT TransferSender
 
     Dispatcher& dispatcher_;
 
-    void registerError();
+    void registerError() const;
 
 public:
     enum { AllIfacesMask = 0xFF };
@@ -43,6 +44,7 @@ public:
                    MonotonicDuration max_transfer_interval = getDefaultMaxTransferInterval())
         : max_transfer_interval_(max_transfer_interval)
         , data_type_(data_type)
+        , priority_(TransferPriorityNormal)
         , qos_(qos)
         , crc_base_(data_type.getSignature().toTransferCRC())
         , flags_(CanIOFlags(0))
@@ -61,6 +63,23 @@ public:
         iface_mask_ = iface_mask;
     }
 
+    /**
+     * Transfer priority can be assigned only for message transfers.
+     * Attempt to change priority of a service transfer will not have any effect.
+     */
+    TransferPriority getPriority() const { return priority_; }
+    void setPriority(TransferPriority prio)
+    {
+        if (prio < NumTransferPriorities && prio != TransferPriorityService)
+        {
+            priority_ = prio;
+        }
+        else
+        {
+            UAVCAN_ASSERT(0);
+        }
+    }
+
     /**
      * Anonymous transfers (i.e. transfers that don't carry a valid Source Node ID) can be sent if
      * the local node is configured in passive mode (i.e. the node doesn't have a valid Node ID).
@@ -76,14 +95,14 @@ public:
      */
     int send(const uint8_t* payload, unsigned payload_len, MonotonicTime tx_deadline,
              MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id,
-             TransferID tid);
+             TransferID tid) const;
 
     /**
      * Send with automatic Transfer ID.
      * TID is managed by OutgoingTransferRegistry.
      */
     int send(const uint8_t* payload, unsigned payload_len, MonotonicTime tx_deadline,
-             MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id);
+             MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id) const;
 };
 
 }
diff --git a/libuavcan/src/transport/uc_frame.cpp b/libuavcan/src/transport/uc_frame.cpp
index 045707006d..a732adf84d 100644
--- a/libuavcan/src/transport/uc_frame.cpp
+++ b/libuavcan/src/transport/uc_frame.cpp
@@ -35,6 +35,7 @@ uint_fast8_t Frame::getMaxIndexForTransferType(const TransferType type)
 
 void Frame::setPriority(const TransferPriority priority)
 {
+    UAVCAN_ASSERT(priority < NumTransferPriorities);
     if (transfer_type_ == TransferTypeMessageBroadcast ||
         transfer_type_ == TransferTypeMessageUnicast)
     {
diff --git a/libuavcan/src/transport/uc_transfer_sender.cpp b/libuavcan/src/transport/uc_transfer_sender.cpp
index f75b3cc149..6f49f7a635 100644
--- a/libuavcan/src/transport/uc_transfer_sender.cpp
+++ b/libuavcan/src/transport/uc_transfer_sender.cpp
@@ -10,14 +10,14 @@
 namespace uavcan
 {
 
-void TransferSender::registerError()
+void TransferSender::registerError() const
 {
     dispatcher_.getTransferPerfCounter().addError();
 }
 
 int TransferSender::send(const uint8_t* payload, unsigned payload_len, MonotonicTime tx_deadline,
                          MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id,
-                         TransferID tid)
+                         TransferID tid) const
 {
     if (payload_len > getMaxPayloadLenForTransferType(transfer_type))
     {
@@ -25,6 +25,12 @@ int TransferSender::send(const uint8_t* payload, unsigned payload_len, Monotonic
     }
 
     Frame frame(data_type_.getID(), transfer_type, dispatcher_.getNodeID(), dst_node_id, 0, tid);
+    if (transfer_type == TransferTypeMessageBroadcast ||
+        transfer_type == TransferTypeMessageUnicast)
+    {
+        UAVCAN_ASSERT(priority_ != TransferPriorityService);
+        frame.setPriority(priority_);
+    }
     UAVCAN_TRACE("TransferSender", "%s", frame.toString().c_str());
 
     /*
@@ -126,7 +132,7 @@ int TransferSender::send(const uint8_t* payload, unsigned payload_len, Monotonic
 }
 
 int TransferSender::send(const uint8_t* payload, unsigned payload_len, MonotonicTime tx_deadline,
-                         MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id)
+                         MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id) const
 {
     // This check must be performed before TID is incremented to avoid skipping TID values on failures
     if (payload_len > getMaxPayloadLenForTransferType(transfer_type))
@@ -134,6 +140,9 @@ int TransferSender::send(const uint8_t* payload, unsigned payload_len, Monotonic
         return -ErrTransferTooLong;
     }
 
+    /*
+     * TODO: TID is not needed for anonymous transfers, this part of the code can be skipped?
+     */
     const OutgoingTransferRegistryKey otr_key(data_type_.getID(), transfer_type, dst_node_id);
 
     UAVCAN_ASSERT(!tx_deadline.isZero());