extern "C" __declspec(dllexport) int FetchByteArray ( int nSize, byte** ppnArray ) \/\/ release the previous buffer, if any allocated.<\/font><\/strong> If you want to use a heap that is shared between native and managed<\/strong>, it is more common to use the COM heap. <\/p>\n one can simple create a console base application which can use this dll. let\u2019s name it MarshallingTest. <\/strong><\/p>\n see the code snippet below.<\/p>\n using System; namespace MarshallingTest int nSum = FetchByteArray(nSize, ref ptrArr); Console.WriteLine("\\nReturned Buffer\\n");<\/strong><\/font><\/p>\n for (int i = 0; i < nSize; i++) <\/strong><\/font><\/p>\n compile and execute you will get following output.<\/p>\n Define a function in native dll (let say it \u201cWin32Native.dll\u201d) as shown below. extern "C" __declspec(dllexport) int FetchByteArray ( int nSize, byte** ppnArray ) { int result = 0; \/\/ CoTaskMemAlloc must be used instead of the new operator because code on the managed side will call \/\/ Marshal.FreeCoTaskMem to free… Continue reading Fetching a byte buffer from a Win32 DLL<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,3,9,15],"tags":[28],"class_list":["post-52","post","type-post","status-publish","format-standard","hentry","category-net","category-codeproject","category-interoperability","category-win32","tag-marshaling","entry"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts\/52","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=52"}],"version-history":[{"count":0,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts\/52\/revisions"}],"wp:attachment":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=52"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=52"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=52"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
{
int result = 0;
\/\/ CoTaskMemAlloc must be used instead of the new operator because code on the managed side will call
\/\/ Marshal.FreeCoTaskMem to free this memory.
byte* newArray = (byte*)CoTaskMemAlloc( sizeof(byte) * nSize );
for ( int j = 0; j < nNewSize ; j++ )
{
newArray[j] = ( j+1 ) % 255 ;
result += newArray[j];
}<\/strong><\/font><\/p>\n
<\/font> if ( *ppnArray != NULL ) CoTaskMemFree( *ppnArray );
*ppnArray = newArray;
return result;
}<\/font><\/strong><\/p>\nPoint of Interest<\/h5>\n
\n
\n
CoTaskMemAlloc()<\/strong><\/code><\/a> and CoTaskMemFree()<\/strong><\/code><\/a>. <\/li>\nMarshal.AllocCoTaskMem()<\/strong><\/code><\/a> and Marshal.FreeCoTaskMem()<\/strong><\/code><\/a>. <\/li>\n<\/ul>\nWriting the client code (the managed part) <\/h5>\n
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;<\/strong><\/font><\/p>\n
{
class Program
{
[DllImport("Win32Native.dll")]
public static extern int FetchByteArray(int nSize, ref IntPtr arrInt);
static void Main(string[] args)
{
int nSize = 10;
IntPtr ptrArr = IntPtr.Zero;<\/strong><\/font><\/p>\n
byte[] arrByte = new byte[nSize];
Marshal.Copy(ptrArr, arrByte, 0, nSize);<\/strong><\/font><\/p>\n
{
Console.Write ( "{0:D2} ", arrByte[i] );
}
Console.Write("\\nSum of Buffer : {0}\\n", nSum );
Marshal.FreeCoTaskMem(ptrArr);
}
}
}
<\/strong><\/font><\/p>\nPoint of Interest<\/h5>\n
\n
![\"image\"](\"http:\/\/praveenkatiyar.wordpress.com\/wp-content\/uploads\/2013\/07\/image_thumb3.png\" "\\"image\\"")
<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"