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rlp: make python code shown actually runnable (both 2.x and 3.x) #69

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rlp: make python code shown actually runnable (both 2.x and 3.x) #69

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31 changes: 20 additions & 11 deletions fundamentals/rlp.md
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Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,8 @@ def encode_length(L,offset):
def to_binary(x):
if x == 0:
return ''
else:
return to_binary(int(x / 256)) + chr(x % 256)
else:
return to_binary(x // 256) + chr(x % 256)
```

## Examples
Expand Down Expand Up @@ -101,15 +101,24 @@ In code, this is:
def rlp_decode(input):
if len(input) == 0:
return
output = ''
(offset, dataLen, type) = decode_length(input)
if type is str:
output = instantiate_str(substr(input, offset, dataLen))
output = str(input[offset:offset+dataLen])
elif type is list:
output = instantiate_list(substr(input, offset, dataLen))
output + rlp_decode(substr(input, offset + dataLen))
output = rlp_decode_list(input[offset:offset+dataLen], [])
return output

def rlp_decode_list(input, items_list):
if len(input) > 0:
(offset, dataLen, type) = decode_length(input)
if type is str:
item = str(input[offset:offset+dataLen])
elif type is list:
item = rlp_decode_list(input[offset:offset+dataLen], [])
return rlp_decode_list(input[offset+dataLen:], items_list + [item])
else:
return items_list

def decode_length(input):
length = len(input)
if length == 0:
Expand All @@ -120,16 +129,16 @@ def decode_length(input):
elif prefix <= 0xb7 and length > prefix - 0x80:
strLen = prefix - 0x80
return (1, strLen, str)
elif prefix <= 0xbf and length > prefix - 0xb7 and length > prefix - 0xb7 + to_integer(substr(input, 1, prefix - 0xb7)):
elif prefix <= 0xbf and length > prefix - 0xb7 and length > prefix - 0xb7 + to_integer(input[1:1+(prefix - 0xb7)]):
lenOfStrLen = prefix - 0xb7
strLen = to_integer(substr(input, 1, lenOfStrLen))
strLen = to_integer(input[1:1+lenOfStrLen])
return (1 + lenOfStrLen, strLen, str)
elif prefix <= 0xf7 and length > prefix - 0xc0:
listLen = prefix - 0xc0;
return (1, listLen, list)
elif prefix <= 0xff and length > prefix - 0xf7 and length > prefix - 0xf7 + to_integer(substr(input, 1, prefix - 0xf7)):
elif prefix <= 0xff and length > prefix - 0xf7 and length > prefix - 0xf7 + to_integer(input[1:1+(prefix - 0xf7)]):
lenOfListLen = prefix - 0xf7
listLen = to_integer(substr(input, 1, lenOfListLen))
listLen = to_integer(input[1:1+lenOfListLen])
return (1 + lenOfListLen, listLen, list)
else:
raise Exception("input don't conform RLP encoding form")
Expand All @@ -141,5 +150,5 @@ def to_integer(b):
elif length == 1:
return ord(b[0])
else:
return ord(substr(b, -1)) + to_integer(substr(b, 0, -1)) * 256
return ord(b[-1:]) + to_integer(b[0:-1]) * 256
```