IVGCVSW-3556 Create the DynamicBackend class

 * Created the new DynamicBackend class with all the necessary
   getters/utility functions
 * Created function types to mirror the backend interface functions

Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
Change-Id: I80a29e6e8a8d0b0655caba63d12cf62e0d8fc832

3 files changed, 154 insertions, 0 deletions

diff --git a/src/backends/backendsCommon/CMakeLists.txt b/src/backends/backendsCommon/CMakeLists.txt
index bb31ce3813..4048c58956 100644
--- a/src/backends/backendsCommon/CMakeLists.txt
+++ b/src/backends/backendsCommon/CMakeLists.txt
@@ -9,6 +9,8 @@ list(APPEND armnnBackendsCommon_sources
     CpuTensorHandle.cpp
     CpuTensorHandleFwd.hpp
     CpuTensorHandle.hpp
+    DynamicBackend.cpp
+    DynamicBackend.hpp
     DynamicBackendUtils.cpp
     DynamicBackendUtils.hpp
     IBackendInternal.hpp
diff --git a/src/backends/backendsCommon/DynamicBackend.cpp b/src/backends/backendsCommon/DynamicBackend.cpp
new file mode 100644
index 0000000000..410265eb38
--- /dev/null
+++ b/src/backends/backendsCommon/DynamicBackend.cpp
@@ -0,0 +1,105 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "DynamicBackend.hpp"
+#include "DynamicBackendUtils.hpp"
+
+namespace armnn
+{
+
+DynamicBackend::DynamicBackend(const void* sharedObjectHandle)
+    : m_BackendIdFunction(nullptr)
+    , m_BackendVersionFunction(nullptr)
+    , m_BackendFactoryFunction(nullptr)
+    , m_Handle(const_cast<void*>(sharedObjectHandle), &DynamicBackendUtils::CloseHandle)
+{
+    if (m_Handle == nullptr)
+    {
+        throw InvalidArgumentException("Cannot create a DynamicBackend object from an invalid shared object handle");
+    }
+
+    // These calls will throw in case of error
+    m_BackendIdFunction      = SetFunctionPointer<IdFunctionType>("GetBackendId");
+    m_BackendVersionFunction = SetFunctionPointer<VersionFunctionType>("GetVersion");
+    m_BackendFactoryFunction = SetFunctionPointer<FactoryFunctionType>("BackendFactory");
+
+    // Check that the backend is compatible with the current Backend API
+    BackendId backendId = GetBackendId();
+    BackendVersion backendVersion = GetBackendVersion();
+    if (!DynamicBackendUtils::IsBackendCompatible(backendVersion))
+    {
+        throw RuntimeException(boost::str(boost::format("The dynamic backend %1% (version %2%) is not compatible"
+                                                        "with the current Backend API (vesion %3%)")
+                                          % backendId
+                                          % backendVersion
+                                          % IBackendInternal::GetApiVersion()));
+    }
+}
+
+BackendId DynamicBackend::GetBackendId()
+{
+    if (m_BackendIdFunction == nullptr)
+    {
+        throw RuntimeException("GetBackendId error: invalid function pointer");
+    }
+
+    return BackendId(m_BackendIdFunction());
+}
+
+BackendVersion DynamicBackend::GetBackendVersion()
+{
+    if (m_BackendVersionFunction == nullptr)
+    {
+        throw RuntimeException("GetBackendVersion error: invalid function pointer");
+    }
+
+    uint32_t major = 0;
+    uint32_t minor = 0;
+    m_BackendVersionFunction(&major, &minor);
+
+    return BackendVersion{ major, minor };
+}
+
+IBackendInternalUniquePtr DynamicBackend::GetBackend()
+{
+    if (m_BackendFactoryFunction == nullptr)
+    {
+        throw RuntimeException("GetBackend error: invalid function pointer");
+    }
+
+    auto backendPointer = reinterpret_cast<IBackendInternal*>(m_BackendFactoryFunction());
+    if (backendPointer == nullptr)
+    {
+        throw RuntimeException("GetBackend error: backend instance must not be null");
+    }
+
+    return std::unique_ptr<IBackendInternal>(backendPointer);
+}
+
+template<typename BackendFunctionType>
+BackendFunctionType DynamicBackend::SetFunctionPointer(const std::string& backendFunctionName)
+{
+    if (m_Handle == nullptr)
+    {
+        throw RuntimeException("SetFunctionPointer error: invalid shared object handle");
+    }
+
+    if (backendFunctionName.empty())
+    {
+        throw RuntimeException("SetFunctionPointer error: backend function name must not be empty");
+    }
+
+    // This call will throw in case of error
+    auto functionPointer = DynamicBackendUtils::GetEntryPoint<BackendFunctionType>(m_Handle.get(),
+                                                                                   backendFunctionName.c_str());
+    if (!functionPointer)
+    {
+        throw RuntimeException("SetFunctionPointer error: invalid backend function pointer returned");
+    }
+
+    return functionPointer;
+}
+
+} // namespace armnn
diff --git a/src/backends/backendsCommon/DynamicBackend.hpp b/src/backends/backendsCommon/DynamicBackend.hpp
new file mode 100644
index 0000000000..06655293e7
--- /dev/null
+++ b/src/backends/backendsCommon/DynamicBackend.hpp
@@ -0,0 +1,47 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+#include "IBackendInternal.hpp"
+
+#include <functional>
+#include <memory>
+
+namespace armnn
+{
+
+class DynamicBackend
+{
+public:
+    using HandleCloser = std::function<void(const void*)>;
+    using HandlePtr = std::unique_ptr<void, HandleCloser>;
+
+    explicit DynamicBackend(const void* sharedObjectHandle);
+
+    /// Public dynamic backend functions
+    BackendId GetBackendId();
+    BackendVersion GetBackendVersion();
+    IBackendInternalUniquePtr GetBackend();
+
+private:
+    template<typename BackendFunctionType>
+    BackendFunctionType SetFunctionPointer(const std::string& backendFunctionName);
+
+    /// Backend function pointer types
+    using IdFunctionType      = const char*(*)();
+    using VersionFunctionType = void(*)(uint32_t*, uint32_t*);
+    using FactoryFunctionType = void*(*)();
+
+    /// Backend function pointers
+    IdFunctionType      m_BackendIdFunction;
+    VersionFunctionType m_BackendVersionFunction;
+    FactoryFunctionType m_BackendFactoryFunction;
+
+    /// Shared object handle
+    HandlePtr m_Handle;
+};
+
+} // namespace armnn