{"id":70,"date":"2013-08-03T14:45:29","date_gmt":"2013-08-03T14:45:29","guid":{"rendered":"https:\/\/praveenkatiyar.wordpress.com\/?p=70"},"modified":"2013-08-03T14:45:29","modified_gmt":"2013-08-03T14:45:29","slug":"fetching-buffer-of-numeric-types-from-a-native-dll","status":"publish","type":"post","link":"https:\/\/praveenkatiyar.in\/blog\/index.php\/2013\/08\/03\/fetching-buffer-of-numeric-types-from-a-native-dll\/","title":{"rendered":"Fetching buffer of numeric types from a Win32 DLL"},"content":{"rendered":"

Define some functions in native dll (let say it \u201cWin32Native.dll<\/strong>\u201d)  as shown below. These 3 functions receives integer buffer, and double buffer respectively.<\/p>\n

extern "C" __declspec(dllexport) int FetchIntegerArray ( int nNewSize, int** ppnArray );<\/font><\/strong><\/span><\/p>\n

extern "C" __declspec(dllexport) double  FetchDoubleArray ( int nNewSize, double ** ppnArray );
<\/font><\/strong><\/span><\/p>\n

Implementing Functions<\/h3>\n

extern "C" __declspec(dllexport) int FetchIntegerArray ( int nNewSize, int** ppnArray )
{
      int result = 0;
      \/\/    CoTaskMemAlloc must be used because code on the managed side will call
      \/\/    Marshal.FreeCoTaskMem to free this memory.
      int* newArray = (int*)CoTaskMemAlloc( sizeof(int) * nNewSize);
      for ( int j = 0; j < nNewSize ; j++ )
      {
           newArray[j] = ( j + 1 ) * 10 ;
           result += newArray[j];
       }<\/strong><\/font><\/span><\/p>\n

      if ( *ppnArray != NULL ) CoTaskMemFree( *ppnArray );
      *ppnArray = newArray;
      return result;
}<\/strong><\/font><\/span><\/p>\n

extern "C" __declspec(dllexport) double  FetchDoubleArray ( int nNewSize, double ** ppnArray )
{
     double result = 0;
     \/\/    CoTaskMemAlloc must be used because code on the managed side will call
     \/\/    Marshal.FreeCoTaskMem to free this memory.
     double* newArray = (double*)CoTaskMemAlloc( sizeof(double) * nNewSize );
     for ( int j = 0; j < nNewSize ; j++ )
     {
         newArray[j] = 10 + ( j+1 ) * 30 ;
         result += newArray[j];
     }<\/strong><\/font><\/span><\/p>\n

     if ( *ppnArray != NULL ) CoTaskMemFree( *ppnArray );
     *ppnArray = newArray;
     return result;
}<\/strong><\/font><\/span><\/p>\n

Point of Interest<\/h4>\n