1 USING: kernel math sequences io.binary splitting grouping ;
6 : count-end ( seq quot -- count )
7 >r [ length ] keep r> find-last drop dup [ - 1- ] [ 2drop 0 ] if ; inline
9 : ch>base64 ( ch -- ch )
10 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" nth ;
12 : base64>ch ( ch -- ch )
14 f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f
15 f f f f f f f f f f 62 f f f 63 52 53 54 55 56 57 58 59 60 61 f f
16 f 0 f f f 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
17 22 23 24 25 f f f f f f 26 27 28 29 30 31 32 33 34 35 36 37 38 39
18 40 41 42 43 44 45 46 47 48 49 50 51
21 : encode3 ( seq -- seq )
22 be> 4 <reversed> [ -6 * shift HEX: 3f bitand ch>base64 ] with B{ } map-as ;
24 : decode4 ( str -- str )
25 0 [ base64>ch swap 6 shift bitor ] reduce 3 >be ;
27 : >base64-rem ( str -- str )
28 [ 3 0 pad-right encode3 ] [ length 1+ ] bi head 4 CHAR: = pad-right ;
32 : >base64 ( seq -- base64 )
33 #! cut string into two pieces, convert 3 bytes at a time
34 #! pad string with = when not enough bits
35 dup length dup 3 mod - cut
36 [ 3 <groups> [ encode3 ] map concat ]
37 [ dup empty? [ drop "" ] [ >base64-rem ] if ]
40 : base64> ( base64 -- str )
41 #! input length must be a multiple of 4
42 [ 4 <groups> [ decode4 ] map concat ]
43 [ [ CHAR: = = not ] count-end ]