一段简单丹麦翻译，求详细！！！

[kyle_huang]

procedure TForm1.Button1Click(Sender: TObject); 
const   
  GetPath = 'E:\Software\DevExpressVCL.v54.rar';   
  SetPath = 'E:\Software\D.rar'; 
var   
  GetStream, SetStream: TStream;   
  intNum, int: Integer;   
  buffer: PByte;   
  intBufferSize, intBlock: Integer; 
begin   
  if not FileExists(GetPath) then   
  begin
    ShowMessage('源文件不存在！');
    Exit;   
  end;   {打开源文件}   
  GetStream := TFileStream.Create(GetPath, fmOpenRead or fmShareExclusive);
  SetStream := TFileStream.Create(SetPath, fmCreate);
  intNum := GetStream.Size; //源文件大小
  SetStream.Size := intNum; //赋给目标文件
  GetStream.Position := 0;  {流指针移到开始, 复制时从这里开始}
  SetStream.Position := 0;
  intBufferSize := intNum;   
  intBlock := intBufferSize div 100;
  GetMem(buffer, intBufferSize);  //给buffer分配空间
  while intNum <> 0 do   begin     
    Application.ProcessMessages;  //避免假死     
    int := intBlock;     
    if int > intNum then       
    int := intNum;     
    GetStream.ReadBuffer(buffer^, int);     
    SetStream.WriteBuffer(buffer^, int);     
    ProgressBar1.Position := Trunc((1 - intNum / intBufferSize) * 100);     
    Dec(intNum, int);  //传了多少，减多少   
  end;
   ...//（后面省略）  

为了更好的理解while循环，求详细解释。特别是ReadBuffer那儿，不怎么理解。30分，够吧？

[UnkownState]

就是拷贝文件，每次从GetStream读取一定的预期字节数int(可能读出的不足int，所以应该加判断)写到SetStream，Buffer为缓冲，Buffer^这么写注意看下WriteBuffer的参数类型就知道了，他不接受指针参数。其实应该对Read的返回值和int比较，然后写SetStream这样严谨。

[kuangning]

function TStream.CopyFrom(Source: TStream; Count: Int64): Int64;
const
MaxBufSize = $F000;
var
BufSize, N: Integer;
Buffer: PChar;
begin
if Count = 0 then
begin
Source.Position := 0;
Count := Source.Size;
end;
Result := Count;
if Count > MaxBufSize then BufSize := MaxBufSize else BufSize := Count;
GetMem(Buffer, BufSize);
try
while Count <> 0 do
begin
if Count > BufSize then N := BufSize else N := Count;
Source.ReadBuffer(Buffer^, N);
WriteBuffer(Buffer^, N);
Dec(Count, N);
end;
finally
FreeMem(Buffer, BufSize);
end;
end;

这是TStream 的源码