1 USING: kernel math sequences namespaces io.binary splitting
7 : count-end ( seq quot -- count )
8 >r [ length ] keep r> find-last drop dup [ - 1- ] [ 2drop 0 ] if ;
10 : ch>base64 ( ch -- ch )
11 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" nth ;
13 : base64>ch ( ch -- ch )
15 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
16 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
17 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
18 22 23 24 25 f f f f f f 26 27 28 29 30 31 32 33 34 35 36 37 38 39
19 40 41 42 43 44 45 46 47 48 49 50 51
22 : encode3 ( seq -- seq )
23 be> 4 [ 3 swap - -6 * shift HEX: 3f bitand ch>base64 ] with map ;
25 : decode4 ( str -- str )
26 [ base64>ch ] map 0 [ swap 6 shift bitor ] reduce 3 >be ;
28 : >base64-rem ( str -- str )
29 [ 3 0 pad-right encode3 ] keep length 1+ head 4 CHAR: = pad-right ;
33 : >base64 ( seq -- base64 )
34 #! cut string into two pieces, convert 3 bytes at a time
35 #! pad string with = when not enough bits
36 dup length dup 3 mod - cut swap
38 3 <groups> [ encode3 % ] each
39 dup empty? [ drop ] [ >base64-rem % ] if
42 : base64> ( base64 -- str )
43 #! input length must be a multiple of 4
45 [ 4 <groups> [ decode4 % ] each ] keep [ CHAR: = = not ] count-end
46 ] SBUF" " make swap [ dup pop* ] times >string ;