{
Copyright © 1999 by Delphi 5 Developer's Guide - Xavier Pacheco and Steve Teixeira
}

library ShareLib;

uses
 ShareMem,
 Windows,
 SysUtils,
 Classes;
const

 cMMFileName: PChar = 'SharedMapData';

{$I DLLDATA.INC}

var
 GlobalData: PGlobalDLLData;
 MapHandle: THandle;

 { GetDLLData will be the exported DLL function }

procedure GetDLLData(var AGlobalData: PGlobalDLLData); stdcall;
begin
 { Point AGlobalData to the same memory address referred to by GlobalData. }
 AGlobalData := GlobalData;
end;

procedure OpenSharedData;
var
 Size: Integer;
begin
 { Get the size of the data to be mapped. }
 Size := SizeOf(TGlobalDLLData);

 { Now get a memory-mapped file object. Note the first parameter passes
 the value $FFFFFFFF or DWord(-1) so that space is allocated from the system's
 paging file. This requires that a name for the memory-mapped
 object get passed as the last parameter. }

 MapHandle := CreateFileMapping(DWord(-1), nil, PAGE_READWRITE, 0, Size,
 cMMFileName);

 if MapHandle = 0 then
 RaiseLastWin32Error;
 { Now map the data to the calling process's address space and get a
 pointer to the beginning of this address }
 GlobalData := MapViewOfFile(MapHandle, FILE_MAP_ALL_ACCESS, 0, 0, Size);
 { Initialize this data }
 GlobalData^.S := 'ShareLib';
 GlobalData^.I := 1;
 if GlobalData = nil then
 begin
 CloseHandle(MapHandle);
 RaiseLastWin32Error;
 end;
end;

procedure CloseSharedData;
{ This procedure un-maps the memory-mapped file and releases the memory-mapped
 file handle }
begin
 UnmapViewOfFile(GlobalData);
 CloseHandle(MapHandle);
end;

procedure DLLEntryPoint(dwReason: DWord);
begin
 case dwReason of
 DLL_PROCESS_ATTACH: OpenSharedData;
 DLL_PROCESS_DETACH: CloseSharedData;
 end;
end;

exports
 GetDLLData;

begin
 { First, assign the procedure to the DLLProc variable }
 DllProc := @DLLEntryPoint;
 { Now invoke the procedure to reflect that the DLL is attaching
 to the process }
 DLLEntryPoint(DLL_PROCESS_ATTACH);
end.