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Add CScriptNum decode python implementation in functional suite #14816

merged 1 commit into from Dec 4, 2018
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Just for now

@@ -25,7 +25,7 @@
bytes_to_hex_str as b2x,

from test_framework.script import CScriptNum

def assert_template(node, block, expect, rehash=True):
if rehash:
@@ -65,11 +65,19 @@ def assert_submitblock(block, result_str_1, result_str_2=None):
assert 'proposal' in tmpl['capabilities']
assert 'coinbasetxn' not in tmpl

coinbase_tx = create_coinbase(height=int(tmpl["height"]) + 1)
next_height = int(tmpl["height"])
coinbase_tx = create_coinbase(height=next_height)
# sequence numbers must not be max for nLockTime to have effect[0].nSequence = 2 ** 32 - 2

# round-trip the encoded bip34 block height commitment
assert_equal(CScriptNum.decode([0].scriptSig), next_height)
# round-trip negative and multi-byte CScriptNums to catch python regression
assert_equal(CScriptNum.decode(CScriptNum.encode(CScriptNum(1500))), 1500)
assert_equal(CScriptNum.decode(CScriptNum.encode(CScriptNum(-1500))), -1500)
assert_equal(CScriptNum.decode(CScriptNum.encode(CScriptNum(-1))), -1)

block = CBlock()
block.nVersion = tmpl["version"]
block.hashPrevBlock = int(tmpl["previousblockhash"], 16)
@@ -385,6 +385,22 @@ def encode(obj):
r[-1] |= 0x80
return bytes([len(r)]) + r

def decode(vch):
result = 0
# We assume valid push_size and minimal encoding
value = vch[1:]
if len(value) == 0:

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practicalswift Nov 28, 2018


If @promag:s suggestions is not implemented: Use if not value: which is more idiomatic

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instagibbs Nov 28, 2018

Author Member

fwiw I wouldn't know hot to read that suggestion properly, sorry

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practicalswift Nov 28, 2018


Yes leave it as is - it was just a nit :-)

I just meant to say that if sequence: and if not sequence: are very common Python idioms for checking non-emptiness and emptiness of sequences. Perhaps this is not the ideal case for my suggestion since it is not obvious from the variable name that value is a sequence :-)

return result
for i, byte in enumerate(value):
result |= int(byte) << 8*i
if value[-1] >= 0x80:
# Mask for all but the highest result bit
num_mask = (2**(len(value)*8) - 1) >> 1
result &= num_mask
result *= -1
return result

class CScript(bytes):
"""Serialized script
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