一个关于DELLPHI的小问题

unit UnitDllMain;interfaceuses windows,UnitNt2000Hook,Sysutils,dialogs,messages;const
   MappingFileName = 'Mapping File Comm DLL';
   Trap=true; {True陷阱式,False改引入表式}
   
type
  TShareMem = packed record
    ComPortFile:array[0..255] of char;
    FileHandle:THandle;
    DatToWriteFile:array[0..255] of char;
    DatToReadFile:array[0..255] of char;
  end;
  PShareMem = ^TShareMem;procedure StartHook(FileBeSpy,readfile,writefile:pchar); stdcall;
procedure StopHook; stdcall;implementationvar
  pShMem : PShareMem;
  hMappingFile : THandle;
  hook:array[0..4]of THookClass;
  FirstProcess:boolean;
  MessageHook:Thandle;
  
function NewCreateFileA(lpFileName: PChar;dwDesiredAccess, dwShareMode: DWORD;
   lpSecurityAttributes: PSecurityAttributes;dwCreationDisposition,dwFlagsAndAttributes: DWORD;
   hTemplateFile: THandle): THandle;stdcall;
type
  TCreateFileA=function(lpFileName: PChar;dwDesiredAccess, dwShareMode: DWORD;
   lpSecurityAttributes: PSecurityAttributes;dwCreationDisposition,dwFlagsAndAttributes: DWORD;
   hTemplateFile: THandle): THandle;stdcall;
begin
   Hook[0].Restore; {改引入表式可以不使用此语句}
   result:=TCreateFileA(hook[0].OldFunction)(lpFileName,dwDesiredAccess,dwShareMode,
      lpSecurityAttributes,dwCreationDisposition,dwFlagsAndAttributes,
      hTemplateFile);   //这里我不是很明白，能请教下这里的意思吗？
   if (stricomp(lpFileName,pShMem^.ComPortFile)=0)or // COM2
      ((plongword(@lpFileName[0])^=$5c2e5c5c)and(stricomp(@lpFileName[4],pShMem^.ComPortFile)=0)) or // \\.\COM2
      ((strlicomp(lpFileName,pShMem^.ComPortFile,4)=0)and(pword(@lpFileName[4])^=$002e))then // COM2.
   begin
      pShMem^.FileHandle:=result;
   end;
   Hook[0].Change; {改引入表式可以不使用此语句}
end;
下面省略。。