64-битное кодирование/декодирование. Вариант 2

Base64Table='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

DecStr:string;

RecodeLine   : array [1..76] of byte;

f1,f2 : word;

l:integer;

l :=length(cStr);

ResStr:='';

for f1:=1 to l do

if cStr[f1]='=' then RecodeLine[f1]:=0

else RecodeLine[f1]:=pos(cStr[f1],Base64Table)-1;

f1:=1;

while f1<length(cStr) do

DecStr:=chr(byte(RecodeLine[f1]   shl 2)+RecodeLine[f1+1] shr 4)+

chr(byte(RecodeLine[f1+1] shl 4)+RecodeLine[f1+2] shr 2)+

chr(byte(RecodeLine[f1+2] shl 6)+RecodeLine[f1+3]);

ResStr:=ResStr+DecStr;

inc(f1,4);

end;

Base64Decode:=ResStr;