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# SPDX-License-Identifier: MIT
class ASCArgumentSection:
def __init__(self, bytes_):
self.blob = bytearray(bytes_)
self.index = self.build_index()
def build_index(self):
off = 0
fields = []
while off < len(self.blob):
snip = self.blob[off:]
key = snip[0:4]
length = int.from_bytes(snip[4:8], byteorder='little')
fields.append((key.decode('ascii'), (off + 8, length)))
off += 8 + length
if off > len(self.blob):
raise ValueError('blob overran during parsing')
return dict(fields)
def items(self):
for key, span in self.index.items():
off, length = span
yield key, self.blob[off:off + length]
def __getitem__(self, key):
off, length = self.index[key]
return bytes(self.blob[off:off + length])
def __setitem__(self, key, value):
off, length = self.index[key]
if type(value) is int:
value = int.to_bytes(value, length, byteorder='little')
elif type(value) is str:
value = value.encode('ascii')
if len(value) > length:
raise ValueError(f'field {key:s} overflown')
self.blob[off:off + length] = value
def update(self, keyvals):
for key, val in keyvals.items():
self[key] = val
def keys(self):
return self.index.keys()
def dump(self):
for key, val in self.items():
print(f"{key:4s} = {val}")
def dump_diff(self, other, logger):
assert self.index == other.index
for key in self.keys():
if self[key] != other[key]:
logger(f"\t{key:4s} = {self[key]} -> {other[key]}")
def to_bytes(self):
return bytes(self.blob)
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