shrub/lib/ethereum.hoon

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::
/- ethereum
=, ^ethereum
=, mimes:html
::
:: ABI spec used for reference:
:: https://ethereum.gitbooks.io/frontier-guide/content/abi.html
::
|%
::
++ encode-params
:> encode list of parameters
|= das=(list data)
^- tape
(encode-data [%array-n das])
::
++ encode-data
:> encode typed data into ABI bytestring.
::
|= dat=data
^- tape
?+ -.dat
~| [%unsupported-type -.dat]
!!
::
%array-n
:: enc(X) = head(X[0]) ... head(X[k-1]) tail(X[0]) ... tail(X[k-1])
:: where head and tail are defined for X[i] being of a static type as
:: head(X[i]) = enc(X[i]) and tail(X[i]) = "" (the empty string), or as
:: head(X[i]) = enc(len(head(X[0])..head(X[k-1]) tail(X[0])..tail(X[i-1])))
:: and tail(X[i]) = enc(X[i]) otherwise.
::
:: so: if it's a static type, data goes in the head. if it's a dynamic
:: type, a reference goes into the head and data goes into the tail.
::
:: in the head, we first put a placeholder where references need to go.
=+ hol=(reap 64 'x')
=/ hes=(list tape)
%+ turn p.dat
|= d=data
?. (is-dynamic-type d) ^$(dat d)
hol
=/ tas=(list tape)
%+ turn p.dat
|= d=data
?. (is-dynamic-type d) ""
^$(dat d)
:: once we know the head and tail, we can fill in the references in head.
=- (weld nes `tape`(zing tas))
^- [@ud nes=tape]
=+ led=(lent (zing hes))
%+ roll hes
|= [t=tape i=@ud nes=tape]
:- +(i)
:: if no reference needed, just put the data.
?. =(t hol) (weld nes t)
:: calculate byte offset of data we need to reference.
=/ ofs/@ud
=- ~& [%full -]
(div - 2) :: two hex digits per byte.
%+ add led :: count head, and
%- lent %- zing :: count all tail data
(scag i tas) :: preceding ours.
~& [%offset-at i ofs `@ux`ofs]
=+ ref=^$(dat [%uint ofs])
:: shouldn't hit this unless we're sending over 2gb of data?
~| [%weird-ref-lent (lent ref)]
?> =((lent ref) (lent hol))
(weld nes ref)
::
%array :: where X has k elements (k is assumed to be of type uint256):
:: enc(X) = enc(k) enc([X[1], ..., X[k]])
:: i.e. it is encoded as if it were an array of static size k, prefixed
:: with the number of elements.
%+ weld $(dat [%uint (lent p.dat)])
$(dat [%array-n p.dat])
::
%bytes-n
:: enc(X) is the sequence of bytes in X padded with zero-bytes to a length
:: of 32.
:: Note that for any X, len(enc(X)) is a multiple of 32.
(pad-to-multiple (render-hex-bytes p.dat) 64 %right)
::
%bytes :: of length k (which is assumed to be of type uint256)
:: enc(X) = enc(k) pad_right(X), i.e. the number of bytes is encoded as a
:: uint256 followed by the actual value of X as a byte sequence, followed
:: by the minimum number of zero-bytes such that len(enc(X)) is a multiple
:: of 32.
%+ weld $(dat [%uint p.p.dat])
$(dat [%bytes-n p.dat])
::
%string
:: enc(X) = enc(enc_utf8(X)), i.e. X is utf-8 encoded and this value is
:: interpreted as of bytes type and encoded further. Note that the length
:: used in this subsequent encoding is the number of bytes of the utf-8
:: encoded string, not its number of characters.
$(dat [%bytes (lent p.dat) (swp 3 (crip p.dat))])
::
%uint
:: enc(X) is the big-endian encoding of X, padded on the higher-order
:: (left) side with zero-bytes such that the length is a multiple of 32
:: bytes.
(pad-to-multiple (render-hex-bytes (as-octs p.dat)) 64 %left)
::
%bool
:: as in the uint8 case, where 1 is used for true and 0 for false
$(dat [%uint ?:(p.dat 1 0)])
::
%address
:: as in the uint160 case
$(dat [%uint `@ud`p.dat])
==
::
++ is-dynamic-type
|= a=data
?. ?=(%array-n -.a)
?=(?(%string %bytes %array) -.a)
&(!=((lent p.a) 0) (lien p.a is-dynamic-type))
::
::
++ render-hex-bytes
:> atom to string of hex bytes without 0x prefix and dots.
|= a=octs
^- tape
=- (weld (reap (sub (mul 2 p.a) (lent -)) '0') -)
(slag 2 (scow %i q.a))
::
++ pad-to-multiple
|= [wat=tape mof=@ud wer=?(%left %right)]
=+ len=(lent wat)
=+ tad=(reap (sub mof (mod len mof)) '0')
%- weld
?:(?=(%left wer) [tad wat] [wat tad])
--