45 lines
1.4 KiB
Factor
45 lines
1.4 KiB
Factor
USING: kernel math sequences io.binary splitting grouping ;
|
|
IN: base64
|
|
|
|
<PRIVATE
|
|
|
|
: count-end ( seq quot -- count )
|
|
>r [ length ] keep r> find-last drop dup [ - 1- ] [ 2drop 0 ] if ; inline
|
|
|
|
: ch>base64 ( ch -- ch )
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" nth ;
|
|
|
|
: base64>ch ( ch -- ch )
|
|
{
|
|
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
|
|
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
|
|
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
|
|
22 23 24 25 f f f f f f 26 27 28 29 30 31 32 33 34 35 36 37 38 39
|
|
40 41 42 43 44 45 46 47 48 49 50 51
|
|
} nth ;
|
|
|
|
: encode3 ( seq -- seq )
|
|
be> 4 <reversed> [ -6 * shift HEX: 3f bitand ch>base64 ] with B{ } map-as ;
|
|
|
|
: decode4 ( str -- str )
|
|
0 [ base64>ch swap 6 shift bitor ] reduce 3 >be ;
|
|
|
|
: >base64-rem ( str -- str )
|
|
[ 3 0 pad-right encode3 ] [ length 1+ ] bi head 4 CHAR: = pad-right ;
|
|
|
|
PRIVATE>
|
|
|
|
: >base64 ( seq -- base64 )
|
|
#! cut string into two pieces, convert 3 bytes at a time
|
|
#! pad string with = when not enough bits
|
|
dup length dup 3 mod - cut
|
|
[ 3 <groups> [ encode3 ] map concat ]
|
|
[ dup empty? [ drop "" ] [ >base64-rem ] if ]
|
|
bi* append ;
|
|
|
|
: base64> ( base64 -- str )
|
|
#! input length must be a multiple of 4
|
|
[ 4 <groups> [ decode4 ] map concat ]
|
|
[ [ CHAR: = = not ] count-end ]
|
|
bi head* ;
|