Delphi内联汇编写的字符串复制函数

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  procedure CopyString(src:PChar; dst:PChar);
implementation
{$R *.dfm}

procedure CopyString(src:PChar; dst:PChar);
var
  n:Integer;
begin
      n:=Length(src);
      asm
        cld           {方向位清0}        
        mov esi,src;  {把源串的地址放到源串寄存器中}
        mov edi,dst;  {把目标串的地址放到目标串寄存器中}
        mov ecx,n;    
        rep movsb;    {movsb只是把ds:esi处的一个字节复制到es:edi,前缀rep是
                       重复执行exc次movsb，每执行一次movsb，esi、edi都会加1}
      end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
    dst:Array[0..6] of char;
begin
    CopyString(PChar(Edit1.Text),dst);
    Edit2.Text:=dst;
end;

end.