Pascal: Runtime error 202 at xxx

Hi all,
ich habe da mal eine Frage. Und zwar habe ich ein Programm zur base64-(De-)Codierung geschrieben. Ich nehme mir mal die Freiheit, es zu posten:
<div class="code">program base64;
var
instr:string;
i:longint;

function p(x,y:longint):integer;
var prod:integer;
begin
if i=0 then exit(1);
if i=1 then exit(x);
prod:=1;
for i:=1 to y do begin
prod:=prod*x;
end;
if i<0 then prod:=1 div prod;
exit(prod);
end;

procedure showhelp;
begin
writeln(stderr,'Syntax f&#65533;r dieses Tool:');
writeln(stderr,' base64 {/e|/d} instring');
writeln(stderr,' /e String nach Base64 codieren');
writeln(stderr,' /d String aus Base64 dekodieren');
writeln(stderr,' instring Zu (de)kodierender String');
end;

function ord64(hchar:char):byte;
begin
case hchar of
'A','=': exit(0);
'B': exit(1);
'C': exit(2);
'D': exit(3);
'E': exit(4);
'F': exit(5);
'G': exit(6);
'H': exit(7);
'I': exit(8);
'J': exit(9);
'K': exit(10);
'L': exit(11);
'M': exit(12);
'N': exit(13);
'O': exit(14);
'P': exit(15);
'Q': exit(16);
'R': exit(17);
'S': exit(18);
'T': exit(19);
'U': exit(20);
'V': exit(21);
'W': exit(22);
'X': exit(23);
'Y': exit(24);
'Z': exit(25);
'a': exit(26);
'b': exit(27);
'c': exit(28);
'd': exit(29);
'e': exit(30);
'f': exit(31);
'g': exit(32);
'h': exit(33);
'i': exit(34);
'j': exit(35);
'k': exit(36);
'l': exit(37);
'm': exit(38);
'n': exit(39);
'o': exit(40);
'p': exit(41);
'q': exit(42);
'r': exit(43);
's': exit(44);
't': exit(45);
'u': exit(46);
'v': exit(47);
'w': exit(48);
'x': exit(49);
'y': exit(50);
'z': exit(51);
'0': exit(52);
'1': exit(53);
'2': exit(54);
'3': exit(55);
'4': exit(56);
'5': exit(57);
'6': exit(58);
'7': exit(59);
'8': exit(60);
'9': exit(61);
'+': exit(62);
'/': exit(63);
else exit(-1);
end;
end;

function chr64(hbyte:byte):char;
begin
case hbyte of
0: exit('A');
1: exit('B');
2: exit('C');
3: exit('D');
4: exit('E');
5: exit('F');
6: exit('G');
7: exit('H');
8: exit('I');
9: exit('J');
10: exit('K');
11: exit('L');
12: exit('M');
13: exit('N');
14: exit('O');
15: exit('P');
16: exit('Q');
17: exit('R');
18: exit('S');
19: exit('T');
20: exit('U');
21: exit('V');
22: exit('W');
23: exit('X');
24: exit('Y');
25: exit('Z');
26: exit('a');
27: exit('b');
28: exit('c');
29: exit('d');
30: exit('e');
31: exit('f');
32: exit('g');
33: exit('h');
34: exit('i');
35: exit('j');
36: exit('k');
37: exit('l');
38: exit('m');
39: exit('n');
40: exit('o');
41: exit('p');
42: exit('q');
43: exit('r');
44: exit('s');
45: exit('t');
46: exit('u');
47: exit('v');
48: exit('w');
49: exit('x');
50: exit('y');
51: exit('z');
52: exit('0');
53: exit('1');
54: exit('2');
55: exit('3');
56: exit('4');
57: exit('5');
58: exit('6');
59: exit('7');
60: exit('8');
61: exit('9');
62: exit('+');
63: exit('/');
else exit('<');
end;
end;

function binconvert(bstr:string):integer;
var
erg,z:integer;

begin
z:=0;
for i:=length(bstr) downto 1 do begin
case bstr[i] of
'0':;
'1':erg:=erg+p(2,z);
else exit(-1);
end;
inc(z);
end;
exit(erg);
end;

procedure decode(hstr:string);
const
z:longint=1;
binastr:string='';
outstr:string='';
var
hlparr:array[1..maxint] of string;

begin
for i:=1 to length(hstr) do begin
if ord64(binastr[i])=-1 then begin
writeln('Ung&#65533;ltiges Zeichen: ',hstr[i]);
exit{(1)};
end;
binastr:=binastr+binstr(ord64(hstr[i]),6);
end;
for i:=0 to length(binastr) do begin
if i mod 8 = 0 then begin
hlparr[z]:=copy(binastr,i,8);
inc(z);
end;
end;
for i:=1 to z do begin
outstr:=outstr+chr(binconvert(hlparr[i]));
end;
writeln(outstr);
end;

procedure encode(hstr:string);
const
binastr:string='';
outstr:string='';
z:longint=1;
var
hlparr: array [1..maxint] of string;

begin
for i:=1 to length(hstr) do begin
binastr:=binastr+binstr(ord(hstr[i]),8);
end;
for i:=0 to length(binastr) do begin
if i mod 6 = 0 then begin
hlparr[z]:=copy(binastr,i,6);
inc(z);
end;
end;
for i:=1 to z do begin
outstr:=outstr+chr64(binconvert(hlparr[i]));
end;
for i:=length(outstr) downto length(outstr)-2 do begin
if outstr[i]='A' then begin
delete(outstr,i,1);
insert('=',outstr,i);
break;
end;
end;
writeln(outstr);
end;

BEGIN
if (paramcount=0) or (paramstr(1)='/?') or (paramstr(1)='/h') or ((paramstr(1)<>'/d') and (paramstr(1)<>'/e')) then showhelp;
instr:=paramstr(2);
if paramstr(1)='/d' then decode(instr);
if paramstr(1)='/e' then encode(instr);
END.</div>
Jedenfalls, wenn ich das kompiliere und starte, bekomme ich folgenden Fehler:
</tt>Runtime error 202 at $00401A2A
$00401A2A
$00401DBD</tt>
Ich habe zwar gelesen, was dieser Fehler bedeutet (Stapelüberlauf), aber ich habe keine Ahnung, wie ich ihn beheben könnte! Help me, please!!!
P.S: Ich nutze Free Pascal.

edit: Nachdem ich die Prozeduren decode und encode ins Hauptprogram geschoben habe, sagt er nur noch "<". Kann sich das einer von euch erklären. Hinweis: Meine Eingabe war <tt>base64 /e abcd</tt>