unit Unit1;

interface

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

type
  ApChar = AnsiChar;
  ApString = AnsiString;
  ApPChar = PAnsiChar;

  TCommatFunc = function(s: ApString): ApString;

  TForm1 = class(TForm)
    btnCommaToPoint: TButton;
    mmo1: TMemo;
    mmo2: TMemo;
    btnFill: TButton;
    Memo1: TMemo;
    procedure btnCommaToPointClick(Sender: TObject);
    procedure btnFillClick(Sender: TObject);
  private
    function RunFunc(Func: TCommatFunc): TDateTime;

    procedure FillRandomText(const iFactor, iCharCount: Integer);
    { Private declarations }
  public
    { Public declarations }
  end;

const
  CNT_RUN = 100000; // РАБОТАЕТ

var
  Form1: TForm1;

implementation

{$R *.DFM}

function ReplaceCharByPChar(s: ApString): ApString;
const
  COMMA_ = ',';
  DOT_ = '.';
var
  P: ApPChar;
  i: Integer;
begin
  Result := s;
  P := Pointer(Result);
  for i := 0 to Length(s) - 1 do
  begin
    if P^ = COMMA_ then
      P^ := DOT_;
    Inc(P);
  end;
end;

function TestMy(s: ApString): ApString;
const
  COMMA_ = ',';
  DOT_ = '.';
var
  P: ApPChar;
begin
  Result := s;
  P := Pointer(Result);
  while P^ <> #0 do
  begin
    if P^ = COMMA_ then
      P^ := DOT_;
    Inc(P);
  end;
end;

function PEnd(s: ApString): ApString;
const
  COMMA_ = ',';
  DOT_ = '.';
var
  P: ApPChar;
  PEnd: Pointer;
begin
  Result := s;
  P := Pointer(Result);
  PEnd := P + Length(s);
  while P < PEnd do
  begin
    if P^ = COMMA_ then
      P^ := DOT_;
    Inc(P);
  end;
end;

function Rep4Bytes(str: ApString): ApString;
const
  COMMA_ = ',';
  DOT_ = '.';
var
  P, C: ApPChar;
  len: Cardinal;
  Sum: NativeUInt;
  Offset: byte;
  i: Integer;
begin
  Result := str;
  P := Pointer(Result);
  len := Length(str);

  while len >= sizeof(ApPChar) do
  begin
    Sum := PNativeUInt(P)^ xor (72340172838076673 * ord(COMMA_));
    if ((Sum - $01010101) and not Sum and $80808080) <> 0 then
    begin
      for Offset := 0 to 3 do
      begin
        C := ApPChar(P + Offset);
        if C^ = COMMA_ then
          C^ := DOT_;
      end;
    end;
    dec(len, sizeof(ApPChar));
    Inc(P, sizeof(ApPChar));
  end;

  while len <> 0 do
  begin
    if P^ = COMMA_ then
      P^ := DOT_;
    dec(len);
    Inc(P);
  end;
end;

var
  MinTest: TDateTime;
  IdxMin, IdxCurr: Integer;

procedure TForm1.btnCommaToPointClick(Sender: TObject);

  function FormatOutput(const aFuncName: ApString; const iRunTime: TDateTime)
    : ApString;
  begin
    Result := Format('%-20s -> %s', [aFuncName, FormatDateTime('NN:SS:ZZZ',
      iRunTime)]);
  end;

begin
  MinTest := TDateTime(1000000000);
  IdxMin := 0;
  IdxCurr := 0;

  mmo1.Lines.Add('------------------------------------------------------');

  mmo1.Lines.Add(FormatOutput('ReplaceCharByPChar',
    RunFunc(@ReplaceCharByPChar)));

  mmo1.Lines.Add(FormatOutput('TestMy', RunFunc(@TestMy)));

  mmo1.Lines.Add(FormatOutput('PEnd', RunFunc(@PEnd)));
  mmo1.Lines.Add(FormatOutput('Rep4Bytes', RunFunc(@Rep4Bytes)));

  mmo1.Lines.Add(FormatOutput('Самый быстрый: ' + (IdxMin + 1).ToString,
    MinTest));

end;

function TForm1.RunFunc(Func: TCommatFunc): TDateTime;
var
  aStartTime: TDateTime;
  i: Integer;
  s: ApString;
begin
  s := mmo2.Text;

  aStartTime := Now;

  for i := 0 to CNT_RUN - 1 do
    Func(s);

  Result := Now - aStartTime;

  if MinTest - Result > 0 then
  begin
    MinTest := Result;
    IdxMin := IdxCurr;
  end;
  Inc(IdxCurr);
end;

procedure TForm1.FillRandomText(const iFactor, iCharCount: Integer);
var
  i: Integer;
  s: ApString;
begin
  s := '';

  for i := 0 to iCharCount do
  begin
    s := s + ','
  end;

  mmo2.Text := s;

end;

procedure TForm1.btnFillClick(Sender: TObject);
begin
  FillRandomText(20, 10000);
end;

end.