Janilabo | RandomRangeEx5()

function RandomRangeEx5(aFrom, aTo, amount: Integer; duplicates: Boolean): TIntArray;
var
  a, d, e, m, r, i, t: Integer;
  tmp: TIntArray;
  b: Boolean;
begin
  if (amount > 0) then
  case duplicates of
    True:
    begin
      SetLength(Result, amount);
      for i := 0 to (amount - 1) do
        Result[i] := RandomRange(aFrom, aTo);
    end;
    False:
    begin
      if (aFrom > aTo) then
        Swap(aFrom, aTo);
      a := IAbs(aTo - aFrom);
      if (a < amount) then
        amount := a;
      if (amount < 1) then
      begin
        Result := [aFrom];
        Exit;
      end;
      SetLength(Result, amount);
      m := IAbs(aFrom - aTo);
      if (m > 10) then
        b := (m > Trunc(amount * 1.1));
      case b of
        True:
        begin
          d := (Trunc(m / amount) + 3);
          e := aFrom;
          for i := 0 to (amount - 1) do
          begin
            r := Random(d);
            IncEx(e, r);
            IncEx(t, (r + 1));
            Result[i] := (e + i);
            Swap(Result[Random(i)], Result[Random(i)]);
            d := (Trunc(((m - t) / (amount - i))) * 2);
          end;
          for i := 0 to (amount div 2) do
            Swap(Result[Random(amount)], Result[Random(amount)]);
        end;
        False:
        begin
          SetLength(tmp, (aTo - aFrom));
          for i := aFrom to (aTo - 1) do
            tmp[(i - aFrom)] := i;
          for i := 0 to (amount - 1) do
          begin
            r := Random((aTo - aFrom) - i);
            Result[i] := tmp[r];
            Delete(tmp, r, 1);
          end;
          SetLength(tmp, 0);
        end;
      end;
    end;
  end;
end;