mirror of
https://github.com/urbit/shrub.git
synced 2024-12-14 20:02:51 +03:00
83 lines
2.1 KiB
Plaintext
83 lines
2.1 KiB
Plaintext
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:: |base64: flexible base64 encoding for little-endian atoms
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::
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:: pad: include padding when encoding, require when decoding
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:: url: use url-safe characters '-' for '+' and '_' for '/'
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::
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=+ [pad=& url=|]
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|%
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:: +en:base64: encode +octs to base64 cord
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::
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++ en
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|= inp=octs
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^- cord
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:: dif: offset from 3-byte block
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::
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=/ dif=@ud (~(dif fo 3) 0 p.inp)
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:: dap: reversed, 3-byte block-aligned input
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::
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=/ dap=@ux (lsh 3 dif (rev 3 inp))
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=/ cha
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?: url
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_'
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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%- crip
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%- flop
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%+ weld
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?.(pad ~ (reap dif '='))
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%+ slag dif
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|- ^- tape
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?: =(0x0 dap) ~
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=/ d (end 3 3 dap)
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:* (cut 3 [(cut 0 [0 6] d) 1] cha)
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(cut 3 [(cut 0 [6 6] d) 1] cha)
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(cut 3 [(cut 0 [12 6] d) 1] cha)
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(cut 3 [(cut 0 [18 6] d) 1] cha)
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$(dap (rsh 3 3 dap))
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==
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:: +de:base64: decode base64 cord to (unit @)
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::
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++ de
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|= a=cord
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^- (unit octs)
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(rush a parse)
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:: +parse:base64: parse base64 cord to +octs
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::
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++ parse
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=< ^- $-(nail (like octs))
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%+ sear reduce
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;~ plug
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%- plus ;~ pose
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(cook |=(a=@ (sub a 'A')) (shim 'A' 'Z'))
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(cook |=(a=@ (sub a 'G')) (shim 'a' 'z'))
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(cook |=(a=@ (add a 4)) (shim '0' '9'))
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(cold 62 (just ?:(url '-' '+')))
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(cold 63 (just ?:(url '_' '/')))
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==
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(stun 0^2 (cold %0 tis))
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==
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|%
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:: +reduce:parse:base64: reduce, measure, and swap base64 digits
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::
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++ reduce
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|= [dat=(list @) dap=(list @)]
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^- (unit octs)
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=/ lat (lent dat)
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=/ lap (lent dap)
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=/ dif (~(dif fo 4) 0 lat)
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?: &(pad !=(dif lap))
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:: padding required and incorrect
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~&(%base-64-padding-err-one ~)
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?: &(!pad !=(0 lap))
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:: padding not required but present
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~&(%base-64-padding-err-two ~)
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=/ len (sub (mul 3 (div (add lat dif) 4)) dif)
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:+ ~ len
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%+ swp 3
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:: %+ base 64
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%+ roll
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(weld dat (reap dif 0))
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|=([p=@ q=@] (add p (mul 64 q)))
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--
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--
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