add Windows version of shared memory, very basic implementation (only allows one single allocation)

examples/SharedMemory/Win32SharedMemory.cpp

@@ -0,0 +1,106 @@
+#ifdef _WIN32
+#include "Win32SharedMemory.h"
+#include "Bullet3Common/b3Logging.h"
+#include "Bullet3Common/b3Scalar.h"
+
+#include <windows.h>
+
+//see also https://msdn.microsoft.com/en-us/library/windows/desktop/aa366551%28v=vs.85%29.aspx
+
+//TCHAR szName[]=TEXT("Global\\MyFileMappingObject2");
+TCHAR szName[]=TEXT("MyFileMappingObject2");
+
+struct Win32SharedMemoryInteralData
+{
+	HANDLE m_hMapFile;
+
+	void*	m_buf;
+
+	Win32SharedMemoryInteralData()
+		:m_hMapFile(0),
+		m_buf(0)
+	{
+	}
+};
+
+Win32SharedMemory::Win32SharedMemory()
+{
+	m_internalData = new Win32SharedMemoryInteralData;
+}
+Win32SharedMemory::~Win32SharedMemory()
+{
+	delete m_internalData;
+}
+
+void*   Win32SharedMemory::allocateSharedMemory(int key, int size)
+{
+	b3Assert(m_internalData->m_buf==0);
+
+	
+	if (this->isServer())
+	{
+	   m_internalData->m_hMapFile = CreateFileMapping(
+                 INVALID_HANDLE_VALUE,    // use paging file
+                 NULL,                    // default security
+                 PAGE_READWRITE,          // read/write access
+                 0,                       // maximum object size (high-order DWORD)
+                 size,						// maximum object size (low-order DWORD)
+                 szName);                 // name of mapping object
+	} else
+	{
+		 m_internalData->m_hMapFile = OpenFileMapping(
+                   FILE_MAP_ALL_ACCESS,   // read/write access
+                   FALSE,                 // do not inherit the name
+                   szName);               // name of mapping object
+
+	}
+
+   if (m_internalData->m_hMapFile == NULL)
+   {
+	   b3Error("Could not create file mapping object (%d).\n",GetLastError());
+      return 0;
+   }
+
+   m_internalData->m_buf =  MapViewOfFile(m_internalData->m_hMapFile,   // handle to map object
+                        FILE_MAP_ALL_ACCESS, // read/write permission
+                        0,
+                        0,
+                        size);
+
+   if (m_internalData->m_buf == NULL)
+	{
+		b3Error("Could not map view of file (%d).\n",GetLastError());
+		CloseHandle(m_internalData->m_hMapFile);
+		return 0;
+   }
+
+   return m_internalData->m_buf;
+}
+void Win32SharedMemory::releaseSharedMemory(int key, int size)
+{
+	if (m_internalData->m_buf)
+	{
+		UnmapViewOfFile(m_internalData->m_buf);
+		m_internalData->m_buf=0;
+	}
+	if (m_internalData->m_hMapFile)
+	{
+		CloseHandle(m_internalData->m_hMapFile);
+	}
+}
+
+Win32SharedMemoryServer::Win32SharedMemoryServer()
+{
+}
+Win32SharedMemoryServer::~Win32SharedMemoryServer()
+{
+}
+
+Win32SharedMemoryClient::Win32SharedMemoryClient()
+{
+}
+Win32SharedMemoryClient:: ~Win32SharedMemoryClient()
+{
+}
+
+#endif //_WIN32