Binary converter (Pascal)

program binario;
uses math;

type TDynamicLongWordList = array of longword;

function binary(n : longword) : string;
var Power2List : TDynamicLongWordList = nil;
    bits : byte = 0;
    i : smallint;
begin
    binary := '';
    bits := trunc(ln(n)/ln(2));
    SetLength(Power2List, bits+1);
    for i := 0 to bits do
        Power2List[bits-i] := trunc(Power(2, i));
    for i := 0 to bits do
        if n >= Power2List[i] then begin
            binary := binary + '1';
            dec(n, Power2List[i]);
        end else
            binary := binary + '0';
end;


function numeric(b : string) : longword;
var Power2List : TDynamicLongWordList = nil;
    bits : byte = 0;
    i : smallint;
begin
    numeric := 0;
    bits := length(b)-1;
    SetLength(Power2List, bits+1);
    for i := 0 to bits do
        Power2List[bits-i] := trunc(Power(2, i));
    for i := 0 to bits do
        if b[i+1] = '1' then
            inc(numeric, Power2List[i]);
end;


var num : longword = 0;
    s : string = '';
begin
    writeln('BINARY TEST');
    repeat
        readln(num);
        if (num > 0) then writeln(num, ' => ', binary(num));
    until num = 0;
    writeln('NUMERIC TEST');
    repeat
        readln(s);
        if (s <> '') and (s <> '0') then writeln(s, ' => ', numeric(s));
    until s = '0';
end.