From d4e49d518a13c01bf15c6c34f6e64bff1fec80a8 Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Thu, 28 May 2015 13:49:01 +0300
Subject: [PATCH] First step towards introducing the global RX object buffer

---
 .../include/uavcan/node/marshal_buffer.hpp    | 11 ++++---
 libuavcan/include/uavcan/node/node.hpp        | 31 ++++++++++---------
 libuavcan/src/node/uc_generic_publisher.cpp   |  4 +--
 libuavcan/test/node/test_node.hpp             |  2 +-
 4 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/libuavcan/include/uavcan/node/marshal_buffer.hpp b/libuavcan/include/uavcan/node/marshal_buffer.hpp
index 35a7e0885a..3dad463a83 100644
--- a/libuavcan/include/uavcan/node/marshal_buffer.hpp
+++ b/libuavcan/include/uavcan/node/marshal_buffer.hpp
@@ -18,7 +18,8 @@ class UAVCAN_EXPORT IMarshalBuffer : public ITransferBuffer
 {
 public:
     virtual const uint8_t* getDataPtr() const = 0;
-    virtual unsigned getDataLength() const = 0;
+    virtual unsigned getMaxWritePos() const = 0;
+    virtual unsigned getSize() const = 0;
 };
 
 /**
@@ -43,10 +44,8 @@ public:
 
 /**
  * Default implementation of marshal buffer provider.
- * This implementation provides the buffer large enough to
- * serialize any UAVCAN data structure.
  */
-template <unsigned MaxSize_ = MaxPossibleTransferPayloadLen>
+template <unsigned MaxSize_>
 class UAVCAN_EXPORT MarshalBufferProvider : public IMarshalBufferProvider
 {
     class Buffer : public IMarshalBuffer
@@ -65,7 +64,9 @@ class UAVCAN_EXPORT MarshalBufferProvider : public IMarshalBufferProvider
 
         virtual const uint8_t* getDataPtr() const { return buf_.getRawPtr(); }
 
-        virtual unsigned getDataLength() const { return buf_.getMaxWritePos(); }
+        virtual unsigned getMaxWritePos() const { return buf_.getMaxWritePos(); }
+
+        virtual unsigned getSize() const { return MaxSize_; }
 
     public:
         void reset() { buf_.reset(); }
diff --git a/libuavcan/include/uavcan/node/node.hpp b/libuavcan/include/uavcan/node/node.hpp
index 65b478b7a7..5175bd2115 100644
--- a/libuavcan/include/uavcan/node/node.hpp
+++ b/libuavcan/include/uavcan/node/node.hpp
@@ -47,21 +47,24 @@ namespace uavcan
  *                                                  be allocated in the memory pool if needed.
  *                                                  Default value is acceptable for any use case.
  *
- * @tparam OutgoingTransferMaxPayloadLen    Maximum outgoing transfer payload length.
- *                                          It's pointless to make this value larger than
- *                                          @ref MaxTransferPayloadLen, which is default.
- *                                          Note that in tiny mode the default value is actually
- *                                          smaller than @ref MaxTransferPayloadLen (may cause
- *                                          run-time failures).
+ * @tparam MarshalBufferSize    Size of the marshal buffer, that is used to provide short-term temporary storage for:
+ *                                1. Serialized data for TX transfers;
+ *                                2. De-serialized data for RX transfers.
+ *                              The buffer must be large enough to accommodate largest serialized TX transfer and
+ *                              largest de-serialized RX data structure. The former value is constant for UAVCAN, the
+ *                              latter is platform-dependent (depends on the field padding, memory alignment, pointer
+ *                              size, etc.).
+ *                              The default value should be enough for all use cases on virtually all platforms.
+ *                              If this value is not large enough, transport objects (such as Subscriber<>,
+ *                              Publisher<>, Service*<>) will be failing at run time during initialization.
  */
 template <std::size_t MemPoolSize_,
 #if UAVCAN_TINY
           unsigned OutgoingTransferRegistryStaticEntries = 0,
-          unsigned OutgoingTransferMaxPayloadLen = 264
 #else
           unsigned OutgoingTransferRegistryStaticEntries = 10,
-          unsigned OutgoingTransferMaxPayloadLen = MaxPossibleTransferPayloadLen
 #endif
+          unsigned MarshalBufferSize = 512
           >
 class UAVCAN_EXPORT Node : public INode
 {
@@ -73,7 +76,7 @@ class UAVCAN_EXPORT Node : public INode
     typedef PoolAllocator<MemPoolSize, MemPoolBlockSize> Allocator;
 
     Allocator pool_allocator_;
-    MarshalBufferProvider<OutgoingTransferMaxPayloadLen> marsh_buf_;
+    MarshalBufferProvider<MarshalBufferSize> marsh_buf_;
     OutgoingTransferRegistry<OutgoingTransferRegistryStaticEntries> outgoing_trans_reg_;
     Scheduler scheduler_;
 
@@ -265,9 +268,8 @@ public:
 
 // ----------------------------------------------------------------------------
 
-template <std::size_t MemPoolSize_, unsigned OutgoingTransferRegistryStaticEntries,
-          unsigned OutgoingTransferMaxPayloadLen>
-int Node<MemPoolSize_, OutgoingTransferRegistryStaticEntries, OutgoingTransferMaxPayloadLen>::start(
+template <std::size_t MemPoolSize_, unsigned OutgoingTransferRegistryStaticEntries, unsigned MarshalBufferSize>
+int Node<MemPoolSize_, OutgoingTransferRegistryStaticEntries, MarshalBufferSize>::start(
     const TransferPriority priority)
 {
     if (started_)
@@ -313,9 +315,8 @@ fail:
 
 #if !UAVCAN_TINY
 
-template <std::size_t MemPoolSize_, unsigned OutgoingTransferRegistryStaticEntries,
-          unsigned OutgoingTransferMaxPayloadLen>
-int Node<MemPoolSize_, OutgoingTransferRegistryStaticEntries, OutgoingTransferMaxPayloadLen>::
+template <std::size_t MemPoolSize_, unsigned OutgoingTransferRegistryStaticEntries, unsigned MarshalBufferSize>
+int Node<MemPoolSize_, OutgoingTransferRegistryStaticEntries, MarshalBufferSize>::
 checkNetworkCompatibility(NetworkCompatibilityCheckResult& result)
 {
     if (!started_)
diff --git a/libuavcan/src/node/uc_generic_publisher.cpp b/libuavcan/src/node/uc_generic_publisher.cpp
index 3ebc7bd699..09f361f5b0 100644
--- a/libuavcan/src/node/uc_generic_publisher.cpp
+++ b/libuavcan/src/node/uc_generic_publisher.cpp
@@ -47,12 +47,12 @@ int GenericPublisherBase::genericPublish(const IMarshalBuffer& buffer, TransferT
 {
     if (tid)
     {
-        return sender_->send(buffer.getDataPtr(), buffer.getDataLength(), getTxDeadline(),
+        return sender_->send(buffer.getDataPtr(), buffer.getMaxWritePos(), getTxDeadline(),
                              blocking_deadline, transfer_type, dst_node_id, *tid);
     }
     else
     {
-        return sender_->send(buffer.getDataPtr(), buffer.getDataLength(), getTxDeadline(),
+        return sender_->send(buffer.getDataPtr(), buffer.getMaxWritePos(), getTxDeadline(),
                              blocking_deadline, transfer_type, dst_node_id);
     }
 }
diff --git a/libuavcan/test/node/test_node.hpp b/libuavcan/test/node/test_node.hpp
index 543f99a50d..5a943ae6da 100644
--- a/libuavcan/test/node/test_node.hpp
+++ b/libuavcan/test/node/test_node.hpp
@@ -20,7 +20,7 @@ struct TestNode : public uavcan::INode
 {
     uavcan::PoolAllocator<uavcan::MemPoolBlockSize * 100, uavcan::MemPoolBlockSize> pool;
     uavcan::PoolManager<1> poolmgr;
-    uavcan::MarshalBufferProvider<> buffer_provider;
+    uavcan::MarshalBufferProvider<512> buffer_provider;
     uavcan::OutgoingTransferRegistry<8> otr;
     uavcan::Scheduler scheduler;
     uint64_t internal_failure_count;