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from __future__ import annotations
import bitarray
from bitstring.exceptions import CreationError
from typing import Union, Iterable, Optional, overload, Iterator, Any
if bitarray.__version__.startswith("2."):
raise ImportError(f"bitstring version 4.3 requires bitarray version 3 or higher. Found version {bitarray.__version__}.")
def indices(s: slice, length: int) -> tuple[int, int | None, int]:
"""A better implementation of slice.indices such that a
slice made from [start:stop:step] will actually equal the original slice."""
if s.step is None or s.step > 0:
return s.indices(length)
assert s.step < 0
start, stop, step = s.indices(length)
if stop < 0:
stop = None
return start, stop, step
def offset_slice_indices_lsb0(key: slice, length: int) -> slice:
start, stop, step = indices(key, length)
if step is not None and step < 0:
if stop is None:
new_start = start + 1
new_stop = None
else:
first_element = start
last_element = start + ((stop + 1 - start) // step) * step
new_start = length - last_element
new_stop = length - first_element - 1
else:
first_element = start
# The last element will usually be stop - 1, but needs to be adjusted if step != 1.
last_element = start + ((stop - 1 - start) // step) * step
new_start = length - last_element - 1
new_stop = length - first_element
return slice(new_start, new_stop, key.step)
class BitStore:
"""A light wrapper around bitarray that does the LSB0 stuff"""
__slots__ = ('_bitarray', 'modified_length', 'immutable')
def __init__(self, initializer: Union[int, bitarray.bitarray, str, None] = None,
immutable: bool = False) -> None:
self._bitarray = bitarray.bitarray(initializer)
self.immutable = immutable
self.modified_length = None
@classmethod
def frombytes(cls, b: Union[bytes, bytearray, memoryview], /) -> BitStore:
x = super().__new__(cls)
x._bitarray = bitarray.bitarray()
x._bitarray.frombytes(b)
x.immutable = False
x.modified_length = None
return x
@classmethod
def frombuffer(cls, buffer, /, length: Optional[int] = None) -> BitStore:
x = super().__new__(cls)
x._bitarray = bitarray.bitarray(buffer=buffer)
x.immutable = True
x.modified_length = length
# Here 'modified' means it shouldn't be changed further, so setting, deleting etc. are disallowed.
if x.modified_length is not None:
if x.modified_length < 0:
raise CreationError("Can't create bitstring with a negative length.")
if x.modified_length > len(x._bitarray):
raise CreationError(
f"Can't create bitstring with a length of {x.modified_length} from {len(x._bitarray)} bits of data.")
return x
def setall(self, value: int, /) -> None:
self._bitarray.setall(value)
def tobytes(self) -> bytes:
if self.modified_length is not None:
return self._bitarray[:self.modified_length].tobytes()
return self._bitarray.tobytes()
def slice_to_uint(self, start: Optional[int] = None, end: Optional[int] = None) -> int:
return bitarray.util.ba2int(self.getslice(start, end)._bitarray, signed=False)
def slice_to_int(self, start: Optional[int] = None, end: Optional[int] = None) -> int:
return bitarray.util.ba2int(self.getslice(start, end)._bitarray, signed=True)
def slice_to_hex(self, start: Optional[int] = None, end: Optional[int] = None) -> str:
return bitarray.util.ba2hex(self.getslice(start, end)._bitarray)
def slice_to_bin(self, start: Optional[int] = None, end: Optional[int] = None) -> str:
return self.getslice(start, end)._bitarray.to01()
def slice_to_oct(self, start: Optional[int] = None, end: Optional[int] = None) -> str:
return bitarray.util.ba2base(8, self.getslice(start, end)._bitarray)
def __iadd__(self, other: BitStore, /) -> BitStore:
self._bitarray += other._bitarray
return self
def __add__(self, other: BitStore, /) -> BitStore:
bs = self._copy()
bs += other
return bs
def __eq__(self, other: Any, /) -> bool:
return self._bitarray == other._bitarray
def __and__(self, other: BitStore, /) -> BitStore:
return BitStore(self._bitarray & other._bitarray)
def __or__(self, other: BitStore, /) -> BitStore:
return BitStore(self._bitarray | other._bitarray)
def __xor__(self, other: BitStore, /) -> BitStore:
return BitStore(self._bitarray ^ other._bitarray)
def __iand__(self, other: BitStore, /) -> BitStore:
self._bitarray &= other._bitarray
return self
def __ior__(self, other: BitStore, /) -> BitStore:
self._bitarray |= other._bitarray
return self
def __ixor__(self, other: BitStore, /) -> BitStore:
self._bitarray ^= other._bitarray
return self
def find(self, bs: BitStore, start: int, end: int, bytealigned: bool = False) -> int:
if not bytealigned:
return self._bitarray.find(bs._bitarray, start, end)
try:
return next(self.findall_msb0(bs, start, end, bytealigned))
except StopIteration:
return -1
def rfind(self, bs: BitStore, start: int, end: int, bytealigned: bool = False):
if not bytealigned:
return self._bitarray.find(bs._bitarray, start, end, right=True)
try:
return next(self.rfindall_msb0(bs, start, end, bytealigned))
except StopIteration:
return -1
def findall_msb0(self, bs: BitStore, start: int, end: int, bytealigned: bool = False) -> Iterator[int]:
if bytealigned is True and len(bs) % 8 == 0:
# Special case, looking for whole bytes on whole byte boundaries
bytes_ = bs.tobytes()
# Round up start byte to next byte, and round end byte down.
# We're only looking for whole bytes, so can ignore bits at either end.
start_byte = (start + 7) // 8
end_byte = end // 8
b = self._bitarray[start_byte * 8: end_byte * 8].tobytes()
byte_pos = 0
bytes_to_search = end_byte - start_byte
while byte_pos < bytes_to_search:
byte_pos = b.find(bytes_, byte_pos)
if byte_pos == -1:
break
yield (byte_pos + start_byte) * 8
byte_pos = byte_pos + 1
return
# General case
i = self._bitarray.search(bs._bitarray, start, end)
if not bytealigned:
for p in i:
yield p
else:
for p in i:
if (p % 8) == 0:
yield p
def rfindall_msb0(self, bs: BitStore, start: int, end: int, bytealigned: bool = False) -> Iterator[int]:
i = self._bitarray.search(bs._bitarray, start, end, right=True)
if not bytealigned:
for p in i:
yield p
else:
for p in i:
if (p % 8) == 0:
yield p
def count(self, value, /) -> int:
return self._bitarray.count(value)
def clear(self) -> None:
self._bitarray.clear()
def reverse(self) -> None:
self._bitarray.reverse()
def __iter__(self) -> Iterable[bool]:
for i in range(len(self)):
yield self.getindex(i)
def _copy(self) -> BitStore:
"""Always creates a copy, even if instance is immutable."""
return BitStore(self._bitarray)
def copy(self) -> BitStore:
return self if self.immutable else self._copy()
def __getitem__(self, item: Union[int, slice], /) -> Union[int, BitStore]:
# Use getindex or getslice instead
raise NotImplementedError
def getindex_msb0(self, index: int, /) -> bool:
return bool(self._bitarray.__getitem__(index))
def getslice_withstep_msb0(self, key: slice, /) -> BitStore:
if self.modified_length is not None:
key = slice(*key.indices(self.modified_length))
return BitStore(self._bitarray.__getitem__(key))
def getslice_withstep_lsb0(self, key: slice, /) -> BitStore:
key = offset_slice_indices_lsb0(key, len(self))
return BitStore(self._bitarray.__getitem__(key))
def getslice_msb0(self, start: Optional[int], stop: Optional[int], /) -> BitStore:
if self.modified_length is not None:
key = slice(*slice(start, stop, None).indices(self.modified_length))
start = key.start
stop = key.stop
return BitStore(self._bitarray[start:stop])
def getslice_lsb0(self, start: Optional[int], stop: Optional[int], /) -> BitStore:
s = offset_slice_indices_lsb0(slice(start, stop, None), len(self))
return BitStore(self._bitarray[s.start:s.stop])
def getindex_lsb0(self, index: int, /) -> bool:
return bool(self._bitarray.__getitem__(-index - 1))
@overload
def setitem_lsb0(self, key: int, value: int, /) -> None:
...
@overload
def setitem_lsb0(self, key: slice, value: BitStore, /) -> None:
...
def setitem_lsb0(self, key: Union[int, slice], value: Union[int, BitStore], /) -> None:
if isinstance(key, slice):
new_slice = offset_slice_indices_lsb0(key, len(self))
self._bitarray.__setitem__(new_slice, value._bitarray)
else:
self._bitarray.__setitem__(-key - 1, value)
def delitem_lsb0(self, key: Union[int, slice], /) -> None:
if isinstance(key, slice):
new_slice = offset_slice_indices_lsb0(key, len(self))
self._bitarray.__delitem__(new_slice)
else:
self._bitarray.__delitem__(-key - 1)
def invert_msb0(self, index: Optional[int] = None, /) -> None:
if index is not None:
self._bitarray.invert(index)
else:
self._bitarray.invert()
def invert_lsb0(self, index: Optional[int] = None, /) -> None:
if index is not None:
self._bitarray.invert(-index - 1)
else:
self._bitarray.invert()
def any_set(self) -> bool:
return self._bitarray.any()
def all_set(self) -> bool:
return self._bitarray.all()
def __len__(self) -> int:
return self.modified_length if self.modified_length is not None else len(self._bitarray)
def setitem_msb0(self, key, value, /):
if isinstance(value, BitStore):
self._bitarray.__setitem__(key, value._bitarray)
else:
self._bitarray.__setitem__(key, value)
def delitem_msb0(self, key, /):
self._bitarray.__delitem__(key)
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