Fix compilation problems on Windows (wang-xinyu#644)

Author: BaofengZan

yolov5/API.h

@@ -0,0 +1,14 @@
+#ifdef API_EXPORTS
+#if defined(_MSC_VER)
+#define API __declspec(dllexport)  
+#else
+#define API __attribute__((visibility("default")))
+#endif
+#else
+
+#if defined(_MSC_VER)
+#define API __declspec(dllimport)  
+#else
+#define API  
+#endif
+#endif

yolov5/CMakeLists.txt

@@ -3,13 +3,17 @@ cmake_minimum_required(VERSION 2.6)
 project(yolov5)
 
 add_definitions(-std=c++11)
-
+add_definitions(-DAPI_EXPORTS)
 option(CUDA_USE_STATIC_CUDA_RUNTIME OFF)
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_BUILD_TYPE Debug)
 
 find_package(CUDA REQUIRED)
 
+if(WIN32)
+enable_language(CUDA) 
+endif(WIN32)
+
 include_directories(${PROJECT_SOURCE_DIR}/include)
 # include and link dirs of cuda and tensorrt, you need adapt them if yours are different
 # cuda
@@ -33,5 +37,7 @@ target_link_libraries(yolov5 cudart)
 target_link_libraries(yolov5 myplugins)
 target_link_libraries(yolov5 ${OpenCV_LIBS})
 
+if(UNIX)
 add_definitions(-O2 -pthread)
+endif(UNIX)
 

yolov5/yololayer.h

@@ -1,6 +1,7 @@
 #ifndef _YOLO_LAYER_H
 #define _YOLO_LAYER_H
 
+#include "API.h"
 #include <vector>
 #include <string>
 #include "NvInfer.h"
@@ -40,7 +41,7 @@ namespace Yolo
 
 namespace nvinfer1
 {
-    class YoloLayerPlugin : public IPluginV2IOExt
+    class API YoloLayerPlugin : public IPluginV2IOExt
     {
     public:
         YoloLayerPlugin(int classCount, int netWidth, int netHeight, int maxOut, const std::vector<Yolo::YoloKernel>& vYoloKernel);
@@ -108,7 +109,7 @@ namespace nvinfer1
         void** mAnchor;
     };
 
-    class YoloPluginCreator : public IPluginCreator
+    class API YoloPluginCreator : public IPluginCreator
     {
     public:
         YoloPluginCreator();