51 lines
1.5 KiB
Factor
51 lines
1.5 KiB
Factor
! Copyright (C) 2008 Doug Coleman.
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! See http://factorcode.org/license.txt for BSD license.
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USING: kernel math sequences io.binary splitting grouping
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accessors ;
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IN: base64
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<PRIVATE
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: count-end ( seq quot -- n )
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trim-right-slice [ seq>> length ] [ to>> ] bi - ; inline
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: ch>base64 ( ch -- ch )
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" nth ;
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: base64>ch ( ch -- ch )
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{
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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
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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
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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
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22 23 24 25 f f f f f f 26 27 28 29 30 31 32 33 34 35 36 37 38 39
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40 41 42 43 44 45 46 47 48 49 50 51
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} nth ;
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: encode3 ( seq -- seq )
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be> 4 <reversed> [
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-6 * shift HEX: 3f bitand ch>base64
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] with B{ } map-as ;
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: decode4 ( str -- str )
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0 [ base64>ch swap 6 shift bitor ] reduce 3 >be ;
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: >base64-rem ( str -- str )
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[ 3 0 pad-right encode3 ] [ length 1+ ] bi
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head-slice 4 CHAR: = pad-right ;
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PRIVATE>
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: >base64 ( seq -- base64 )
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#! cut string into two pieces, convert 3 bytes at a time
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#! pad string with = when not enough bits
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dup length dup 3 mod - cut
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[ 3 <groups> [ encode3 ] map concat ]
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[ [ "" ] [ >base64-rem ] if-empty ]
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bi* append ;
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: base64> ( base64 -- seq )
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#! input length must be a multiple of 4
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[ 4 <groups> [ decode4 ] map concat ]
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[ [ CHAR: = = ] count-end ]
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bi head* ;
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