base64 decoder in sql procedure or function, anyone?

[Lennart]

Before I rush of and start implementing one, I just want to check
whether someone already did and is willing to share their code? For
reasons that are beyond my control I need an sql implementation (i.e.
no java or c allowed).

Thanx
/Lennart

[Lennart]

Probably useless for everyone else, but I'll post a partial solution
anyhow. It *almost* works :-) I haven't had the time to figure out why
it is bailing out after a number of characters.

create function base64.decode_char ( c varchar(1) )
returns char
begin atomic
declare x int;
set x = ascii(c);
return
case
when x between 65 and 90 then chr( x - ascii('A') )
when x between 97 and 122 then chr( x - ascii('a') + 26 )
when x between 48 and 57 then chr( x - ascii('0') + 52 )
when x = 43 then chr(62)
else chr(63)
end;
end @

create function base64.decode_str ( s varchar(4000) )
returns varchar(4000)
begin atomic
declare n int;
declare len int;
declare res varchar(4000);

declare b1 char;
declare b2 char;
declare b3 char;
declare b4 char;

declare s1 char;
declare s2 char;
declare s3 char;

set n = 1;
set len = length(rtrim(s));
set res = '';

while n <= len do
set b1 = base64.decode_char( substr(s,n,1) );
set b2 = base64.decode_char( substr(s,n+1,1) );
set b3 = base64.decode_char( substr(s,n+2,1) );
set b4 = base64.decode_char( substr(s,n+3,1) );

set s1 = case when n+1 <= len then
chr( bitor(ascii(b1)*power(2,2),
ascii(b2)/power(2,4)
))
else ''
end;
set s2 = case when n+2 <= len then
chr( bitor( bitand(ascii(b2),15)*power(2,4),
ascii(b3)/power(2,2)
))
else ''
end;
set s3 = case when n+3 <= len then
chr( bitor( bitand(ascii(b3),3)*power(2,6),
ascii(b4)
))
else ''
end;
set res = rtrim(res) || s1 || s2 || s3;
set n = n + 4;
end while;
return res;
end @

Hmm, fft, huffman, ... ;-)

/Lennart