[تمرين] مولد ارقام عشوائية (RandomGenerator)

كود :
///////////////////////////////////////////
/////// Random Generator by bo0oda ///////
///////         31-8-2010         ///////
////////////////////////////////////////
unit RandomGenerator;

interface
uses
Windows;//only for GetTickCount;
type
   TRandomGenerator = class(TObject)

   private
     LastBoolean : Byte;//0:True 1 : False 2:Nothing
     lastValue : Extended;
     function RandomNumber(Range : Extended):Extended;
    public
     RangeFrom : Extended;
    RangeTo : Extended;
    seed: Extended;
    TruePercnt: Single;
    Duplicate: Boolean;// defult is fulse = duplicate valuse ; true = non duplicate
    function Next(): Integer;//Retrieves the next random integer
    function NextDouble():Extended;//Retrieves the next random Extended
    function NextBoolean(): Boolean;//Retrieves the next random Boolean
    constructor Create();
  end;
implementation


constructor TRandomGenerator.Create();
begin
  RangeFrom:= 0;
  RangeTo:= 100;
  lastValue:= 0;
  TruePercnt:= 50;;
  lastValue:= 0;
  LastBoolean:= 2;
end;
// new mod coz the result of orginal one is integer;
function _mod(Dividend,Divisor : Extended):Extended;
var
quotient: Extended;
begin
Quotient:= TRunc(Dividend) Div TRunc(Divisor);
Result:= Dividend - (Quotient * Divisor)
end;
// this function to give you random number in your range
function TRandomGenerator.RandomNumber(Range : Extended):Extended;
var
k : Int64;
begin
if Range <> 0 then //Checking if range != 0
begin
// set seed first
if seed = 0 then
seed:= GetTickCount;
//Math Operation
try
  Result:= seed * 65536*1989.0115+0.1028 ;
 Result:= _mod(Result,Range);
 while Duplicate and (Result = lastValue)  do
  begin
 Result:= seed * 65536*1989.0115+0.1028 ;
 Result:= _mod(Result,Range);
 seed:= (seed * seed) + 1;
 end;
except
  Result:= Range-1;
end;
lastValue:= Result;
seed:= lastValue;
end else Result:= 0; //if range = 0;
end;
 function TRandomGenerator.NextDouble(): Extended;
 begin
 If RangeFrom > RangeTo then
   Result:= RandomNumber(RangeFrom - RangeTo) + RangeTo
 else
  REsult:= RandomNumber(RangeTo- RangeFrom) + RangeFrom  ;

 end;
  function TRandomGenerator.Next(): Integer;
 begin
 If RangeFrom > RangeTo then
   Result:= Trunc(RandomNumber(RangeFrom - RangeTo) + RangeTo)
 else
  REsult:= Trunc(RandomNumber(RangeTo- RangeFrom) + RangeFrom) ;

 end;


 function TRandomGenerator.NextBoolean(): Boolean;
 var
 P: Single;
 begin
  if Duplicate and (LastBoolean <>2)then
 begin
 case LastBoolean of
 0:begin
 Result:= False;
 LastBoolean:= 1;
 end;
 1:begin
 Result:= True;
 LastBoolean:= 0;
 end;
 end;
 end else
 begin
 P:= RandomNumber(100);
 Result := p < TruePercnt;
 if Result then LastBoolean:= 0 else
  LastBoolean:= 1;
 end;
 end;

end.