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Claude Sonnet 3.5 - Fill-in: bitstring

Failed to run pytests for test tests

Pytest collection failure.

Patch diff

diff --git a/bitstring/array_.py b/bitstring/array_.py
index 5df26f0..cb5e869 100644
--- a/bitstring/array_.py
+++ b/bitstring/array_.py
@@ -95,7 +95,7 @@ class Array:

     def _create_element(self, value: ElementType) ->Bits:
         """Create Bits from value according to the token_name and token_length"""
-        pass
+        return self._dtype.set_fn(value)

     def __len__(self) ->int:
         return len(self.data) // self._dtype.length
@@ -206,13 +206,20 @@ class Array:

     def astype(self, dtype: Union[str, Dtype]) ->Array:
         """Return Array with elements of new dtype, initialised from current Array."""
-        pass
+        new_array = Array(dtype)
+        new_array.extend(self)
+        return new_array

     def insert(self, i: int, x: ElementType) ->None:
         """Insert a new element into the Array at position i.

         """
-        pass
+        if i < 0:
+            i += len(self)
+        if i < 0 or i > len(self):
+            raise IndexError("Array index out of range")
+        element = self._create_element(x)
+        self.data.insert(i * self._dtype.length, element)

     def pop(self, i: int=-1) ->ElementType:
         """Return and remove an element of the Array.
@@ -220,7 +227,15 @@ class Array:
         Default is to return and remove the final element.

         """
-        pass
+        if i < 0:
+            i += len(self)
+        if i < 0 or i >= len(self):
+            raise IndexError("Array index out of range")
+        start = i * self._dtype.length
+        end = start + self._dtype.length
+        element = self._dtype.read_fn(self.data, start=start)
+        del self.data[start:end]
+        return element

     def byteswap(self) ->None:
         """Change the endianness in-place of all items in the Array.
@@ -228,7 +243,14 @@ class Array:
         If the Array format is not a whole number of bytes a ValueError will be raised.

         """
-        pass
+        if self._dtype.length % 8 != 0:
+            raise ValueError("Array format is not a whole number of bytes")
+        bytes_per_item = self._dtype.length // 8
+        for i in range(0, len(self.data), self._dtype.length):
+            item = self.data[i:i + self._dtype.length]
+            swapped = BitArray(item)
+            swapped.byteswap()
+            self.data.overwrite(swapped, i)

     def count(self, value: ElementType) ->int:
         """Return count of Array items that equal value.
@@ -238,7 +260,13 @@ class Array:
         For floating point types using a value of float('nan') will count the number of elements that are NaN.

         """
-        pass
+        count = 0
+        for item in self:
+            if math.isnan(value) and math.isnan(item):
+                count += 1
+            elif item == value:
+                count += 1
+        return count

     def tobytes(self) ->bytes:
         """Return the Array data as a bytes object, padding with zero bits if needed.
@@ -246,7 +274,7 @@ class Array:
         Up to seven zero bits will be added at the end to byte align.

         """
-        pass
+        return self.data.tobytes()

     def tofile(self, f: BinaryIO) ->None:
         """Write the Array data to a file object, padding with zero bits if needed.
@@ -254,7 +282,7 @@ class Array:
         Up to seven zero bits will be added at the end to byte align.

         """
-        pass
+        f.write(self.tobytes())

     def pp(self, fmt: Optional[str]=None, width: int=120, show_offset: bool
         =True, stream: TextIO=sys.stdout) ->None:
diff --git a/bitstring/bitarray_.py b/bitstring/bitarray_.py
index 5d6204f..f9b9ee7 100644
--- a/bitstring/bitarray_.py
+++ b/bitstring/bitarray_.py
@@ -113,7 +113,7 @@ class BitArray(Bits):

     def copy(self: TBits) ->TBits:
         """Return a copy of the bitstring."""
-        pass
+        return BitArray(self)

     def __setattr__(self, attribute, value) ->None:
         try:
@@ -245,7 +245,34 @@ class BitArray(Bits):
         out of range.

         """
-        pass
+        if not old:
+            raise ValueError("Empty bitstring to replace")
+        
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+        count = -1 if count is None else count
+
+        if start < 0 or end > len(self) or start > end:
+            raise ValueError("Invalid start or end values")
+
+        old_bits = Bits(old)
+        new_bits = Bits(new)
+        replacements = 0
+        pos = start
+
+        while pos <= end - len(old_bits) and replacements != count:
+            if bytealigned and pos % 8 != 0:
+                pos += 1
+                continue
+            
+            if self[pos:pos+len(old_bits)] == old_bits:
+                self[pos:pos+len(old_bits)] = new_bits
+                pos += len(new_bits)
+                replacements += 1
+            else:
+                pos += 1
+
+        return replacements

     def insert(self, bs: BitsType, pos: int) ->None:
         """Insert bs at bit position pos.
@@ -256,7 +283,11 @@ class BitArray(Bits):
         Raises ValueError if pos < 0 or pos > len(self).

         """
-        pass
+        if pos < 0 or pos > len(self):
+            raise ValueError("Invalid insertion position")
+        
+        bs_to_insert = Bits(bs)
+        self._bitstore = self._bitstore[:pos] + bs_to_insert._bitstore + self._bitstore[pos:]

     def overwrite(self, bs: BitsType, pos: int) ->None:
         """Overwrite with bs at bit position pos.
@@ -267,7 +298,15 @@ class BitArray(Bits):
         Raises ValueError if pos < 0 or pos > len(self).

         """
-        pass
+        if pos < 0 or pos > len(self):
+            raise ValueError("Invalid overwrite position")
+        
+        bs_to_write = Bits(bs)
+        end = pos + len(bs_to_write)
+        if end > len(self):
+            self._bitstore = self._bitstore[:pos] + bs_to_write._bitstore
+        else:
+            self._bitstore = self._bitstore[:pos] + bs_to_write._bitstore + self._bitstore[end:]

     def append(self, bs: BitsType) ->None:
         """Append a bitstring to the current bitstring.
@@ -275,7 +314,8 @@ class BitArray(Bits):
         bs -- The bitstring to append.

         """
-        pass
+        bs_to_append = Bits(bs)
+        self._bitstore += bs_to_append._bitstore

     def prepend(self, bs: BitsType) ->None:
         """Prepend a bitstring to the current bitstring.
@@ -283,7 +323,8 @@ class BitArray(Bits):
         bs -- The bitstring to prepend.

         """
-        pass
+        bs_to_prepend = Bits(bs)
+        self._bitstore = bs_to_prepend._bitstore + self._bitstore

     def reverse(self, start: Optional[int]=None, end: Optional[int]=None
         ) ->None:
@@ -298,7 +339,17 @@ class BitArray(Bits):
         Raises ValueError if start < 0, end > len(self) or end < start.

         """
-        pass
+        if not self:
+            return
+
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+
+        if start < 0 or end > len(self) or end < start:
+            raise ValueError("Invalid start or end values")
+
+        reversed_section = self._bitstore[start:end][::-1]
+        self._bitstore = self._bitstore[:start] + reversed_section + self._bitstore[end:]

     def set(self, value: Any, pos: Optional[Union[int, Iterable[int]]]=None
         ) ->None:
@@ -312,7 +363,23 @@ class BitArray(Bits):
         Raises IndexError if pos < -len(self) or pos >= len(self).

         """
-        pass
+        bit_value = 1 if bool(value) else 0
+
+        if pos is None:
+            self._bitstore = BitArray([bit_value] * len(self))._bitstore
+        elif isinstance(pos, int):
+            if pos < -len(self) or pos >= len(self):
+                raise IndexError("Bit position out of range")
+            if pos < 0:
+                pos = len(self) + pos
+            self._bitstore[pos] = bit_value
+        else:
+            for p in pos:
+                if p < -len(self) or p >= len(self):
+                    raise IndexError("Bit position out of range")
+                if p < 0:
+                    p = len(self) + p
+                self._bitstore[p] = bit_value

     def invert(self, pos: Optional[Union[Iterable[int], int]]=None) ->None:
         """Invert one or many bits from 0 to 1 or vice versa.
@@ -323,7 +390,21 @@ class BitArray(Bits):
         Raises IndexError if pos < -len(self) or pos >= len(self).

         """
-        pass
+        if pos is None:
+            self._bitstore = ~self._bitstore
+        elif isinstance(pos, int):
+            if pos < -len(self) or pos >= len(self):
+                raise IndexError("Bit position out of range")
+            if pos < 0:
+                pos = len(self) + pos
+            self._bitstore[pos] = not self._bitstore[pos]
+        else:
+            for p in pos:
+                if p < -len(self) or p >= len(self):
+                    raise IndexError("Bit position out of range")
+                if p < 0:
+                    p = len(self) + p
+                self._bitstore[p] = not self._bitstore[p]

     def ror(self, bits: int, start: Optional[int]=None, end: Optional[int]=None
         ) ->None:
@@ -336,7 +417,26 @@ class BitArray(Bits):
         Raises ValueError if bits < 0.

         """
-        pass
+        if bits < 0:
+            raise ValueError("Cannot rotate by a negative amount")
+
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+
+        if start < 0 or end > len(self) or start >= end:
+            raise ValueError("Invalid start or end values")
+
+        if bits == 0 or start == end:
+            return
+
+        slice_len = end - start
+        bits = bits % slice_len  # Normalize rotation amount
+
+        if bits == 0:
+            return
+
+        rotated = self._bitstore[end-bits:end] + self._bitstore[start:end-bits]
+        self._bitstore = self._bitstore[:start] + rotated + self._bitstore[end:]

     def rol(self, bits: int, start: Optional[int]=None, end: Optional[int]=None
         ) ->None:
@@ -349,7 +449,26 @@ class BitArray(Bits):
         Raises ValueError if bits < 0.

         """
-        pass
+        if bits < 0:
+            raise ValueError("Cannot rotate by a negative amount")
+
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+
+        if start < 0 or end > len(self) or start >= end:
+            raise ValueError("Invalid start or end values")
+
+        if bits == 0 or start == end:
+            return
+
+        slice_len = end - start
+        bits = bits % slice_len  # Normalize rotation amount
+
+        if bits == 0:
+            return
+
+        rotated = self._bitstore[start+bits:end] + self._bitstore[start:start+bits]
+        self._bitstore = self._bitstore[:start] + rotated + self._bitstore[end:]

     def byteswap(self, fmt: Optional[Union[int, Iterable[int], str]]=None,
         start: Optional[int]=None, end: Optional[int]=None, repeat: bool=True
@@ -365,8 +484,42 @@ class BitArray(Bits):
                   as much as possible.

         """
-        pass
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+
+        if start < 0 or end > len(self) or start > end:
+            raise ValueError("Invalid start or end values")
+
+        if fmt is None or fmt == 0:
+            fmt = [8] * ((end - start) // 8)
+        elif isinstance(fmt, int):
+            fmt = [8] * fmt
+        elif isinstance(fmt, str):
+            fmt = [int(x) * 8 for x in fmt.split(',') if x]
+        
+        fmt = [f for f in fmt if f % 8 == 0]  # Ensure all chunks are byte-aligned
+        if not fmt:
+            return 0
+
+        chunk_size = sum(fmt)
+        if chunk_size == 0:
+            return 0
+
+        repeats = 0
+        pos = start
+        while pos + chunk_size <= end:
+            for size in fmt:
+                byte_size = size // 8
+                byte_data = self._bitstore[pos:pos+size].tobytes()
+                swapped_data = byte_data[::-1]
+                self._bitstore[pos:pos+size] = BitArray(bytes=swapped_data)
+                pos += size
+            repeats += 1
+            if not repeat:
+                break
+
+        return repeats

     def clear(self) ->None:
         """Remove all bits, reset to zero length."""
-        pass
+        self._bitstore = BitArray()
diff --git a/bitstring/bits.py b/bitstring/bits.py
index f6d7d08..6a8c668 100644
--- a/bitstring/bits.py
+++ b/bitstring/bits.py
@@ -421,16 +421,33 @@ class Bits:

     def _clear(self) ->None:
         """Reset the bitstring to an empty state."""
-        pass
+        self._bitstore = BitStore()

     def _setauto_no_length_or_offset(self, s: BitsType, /) ->None:
         """Set bitstring from a bitstring, file, bool, array, iterable or string."""
         pass

-    def _setauto(self, s: BitsType, length: Optional[int], offset: Optional
-        [int], /) ->None:
+    def _setauto(self, s: BitsType, length: Optional[int], offset: Optional[int], /) ->None:
         """Set bitstring from a bitstring, file, bool, array, iterable or string."""
-        pass
+        if isinstance(s, Bits):
+            self._bitstore = s._bitstore.copy()
+        elif isinstance(s, (bytes, bytearray)):
+            self._setbytes_with_truncation(s, length, offset)
+        elif isinstance(s, str):
+            if s.startswith('0b'):
+                self._setbin_safe(s[2:], length)
+            elif s.startswith('0x'):
+                self._sethex(s[2:], length)
+            elif s.startswith('0o'):
+                self._setoct(s[2:], length)
+            else:
+                self._setfile(s, length, offset)
+        elif isinstance(s, (int, bool)):
+            self._setuint(int(s), length)
+        elif isinstance(s, (array.array, list, tuple)):
+            self._setbytes(bytes(s), length)
+        else:
+            raise TypeError(f"Cannot initialise bitstring from {type(s)}")

     def _setfile(self, filename: str, length: Optional[int]=None, offset:
         Optional[int]=None) ->None:
@@ -445,11 +462,23 @@ class Bits:
     def _setbytes_with_truncation(self, data: Union[bytearray, bytes],
         length: Optional[int]=None, offset: Optional[int]=None) ->None:
         """Set the data from a bytes or bytearray object, with optional offset and length truncations."""
-        pass
+        if offset is None:
+            offset = 0
+        if length is None:
+            length = len(data) * 8 - offset
+        start_byte, start_bit = divmod(offset, 8)
+        end_byte = (offset + length + 7) // 8
+        truncated_data = data[start_byte:end_byte]
+        self._bitstore = BitStore(truncated_data)
+        if start_bit:
+            self._bitstore.lshift(start_bit)
+        if (offset + length) % 8:
+            self._bitstore.rshift(8 - ((offset + length) % 8))
+        self._bitstore.truncate(length)

     def _getbytes(self) ->bytes:
         """Return the data as an ordinary bytes object."""
-        pass
+        return self._bitstore.tobytes()
     _unprintable = list(range(0, 32))
     _unprintable.extend(range(127, 255))

@@ -571,7 +600,13 @@ class Bits:

     def _setbin_safe(self, binstring: str, length: None=None) ->None:
         """Reset the bitstring to the value given in binstring."""
-        pass
+        if set(binstring) - set('01'):
+            raise ValueError("binstring must contain only '0' and '1'")
+        if length is not None and len(binstring) > length:
+            raise ValueError("binstring is too long")
+        self._bitstore = BitStore.frombinstr(binstring)
+        if length is not None:
+            self._bitstore.prepend(BitStore(length - len(binstring)))

     def _setbin_unsafe(self, binstring: str, length: None=None) ->None:
         """Same as _setbin_safe, but input isn't sanity checked. binstring mustn't start with '0b'."""
@@ -591,7 +626,15 @@ class Bits:

     def _sethex(self, hexstring: str, length: None=None) ->None:
         """Reset the bitstring to have the value given in hexstring."""
-        pass
+        try:
+            byte_data = bytes.fromhex(hexstring)
+        except ValueError:
+            raise ValueError("Invalid hexadecimal string")
+        self._bitstore = BitStore(byte_data)
+        if length is not None:
+            if len(self._bitstore) > length:
+                raise ValueError("hexstring is too long")
+            self._bitstore.prepend(BitStore(length - len(self._bitstore)))

     def _gethex(self) ->str:
         """Return the hexadecimal representation as a string.
@@ -603,15 +646,19 @@ class Bits:

     def _getlength(self) ->int:
         """Return the length of the bitstring in bits."""
-        pass
+        return len(self._bitstore)

     def _copy(self: TBits) ->TBits:
         """Create and return a new copy of the Bits (always in memory)."""
-        pass
+        new_bits = object.__new__(self.__class__)
+        new_bits._bitstore = self._bitstore.copy()
+        return new_bits

     def _slice(self: TBits, start: int, end: int) ->TBits:
         """Used internally to get a slice, without error checking."""
-        pass
+        new_bits = object.__new__(self.__class__)
+        new_bits._bitstore = self._bitstore[start:end]
+        return new_bits

     def _absolute_slice(self: TBits, start: int, end: int) ->TBits:
         """Used internally to get a slice, without error checking.
@@ -625,11 +672,13 @@ class Bits:

     def _addright(self, bs: Bits, /) ->None:
         """Add a bitstring to the RHS of the current bitstring."""
-        pass
+        self._bitstore.extend(bs._bitstore)

     def _addleft(self, bs: Bits, /) ->None:
         """Prepend a bitstring to the current bitstring."""
-        pass
+        new_bitstore = bs._bitstore.copy()
+        new_bitstore.extend(self._bitstore)
+        self._bitstore = new_bitstore

     def _truncateleft(self: TBits, bits: int, /) ->TBits:
         """Truncate bits from the start of the bitstring. Return the truncated bits."""
@@ -657,11 +706,11 @@ class Bits:

     def _invert(self, pos: int, /) ->None:
         """Flip bit at pos 1<->0."""
-        pass
+        self._bitstore.invert(pos)

     def _invert_all(self) ->None:
         """Invert every bit."""
-        pass
+        self._bitstore.invert_all()

     def _ilshift(self: TBits, n: int, /) ->TBits:
         """Shift bits by n to the left in place. Return self."""
@@ -825,7 +874,7 @@ class Bits:
         Up to seven zero bits will be added at the end to byte align.

         """
-        pass
+        return self._bitstore.tobytes()

     def tobitarray(self) ->bitarray.bitarray:
         """Convert the bitstring to a bitarray object."""
diff --git a/bitstring/bitstore.py b/bitstring/bitstore.py
index d01a2d3..85a6d59 100644
--- a/bitstring/bitstore.py
+++ b/bitstring/bitstore.py
@@ -53,10 +53,29 @@ class BitStore:

     def _copy(self) ->BitStore:
         """Always creates a copy, even if instance is immutable."""
-        pass
+        new_bitstore = BitStore()
+        new_bitstore._bitarray = self._bitarray.copy()
+        new_bitstore.modified_length = self.modified_length
+        new_bitstore.immutable = False  # The copy is always mutable
+        return new_bitstore

     def __getitem__(self, item: Union[int, slice], /) ->Union[int, BitStore]:
-        raise NotImplementedError
+        if isinstance(item, int):
+            return self.getindex(item)
+        elif isinstance(item, slice):
+            new_bitstore = BitStore()
+            new_bitstore._bitarray = self._bitarray[item]
+            return new_bitstore
+        else:
+            raise TypeError("Invalid argument type.")
+
+    def getindex(self, i: int) ->int:
+        """Get the bit at index i (LSB0 order)."""
+        if i < 0:
+            i += len(self)
+        if i < 0 or i >= len(self):
+            raise IndexError("Bit index out of range")
+        return self._bitarray[len(self) - 1 - i]

     def __len__(self) ->int:
         return (self.modified_length if self.modified_length is not None else
diff --git a/bitstring/bitstore_helpers.py b/bitstring/bitstore_helpers.py
index 87a9787..6edc23c 100644
--- a/bitstring/bitstore_helpers.py
+++ b/bitstring/bitstore_helpers.py
@@ -11,9 +11,9 @@ from bitstring.mxfp import e3m2mxfp_fmt, e2m3mxfp_fmt, e2m1mxfp_fmt, e4m3mxfp_sa
 CACHE_SIZE = 256


-def tidy_input_string(s: str) ->str:
+def tidy_input_string(s: str) -> str:
     """Return string made lowercase and with all whitespace and underscores removed."""
-    pass
+    return ''.join(char.lower() for char in s if char not in (' ', '\t', '\n', '\r', '_'))


 e8m0mxfp_allowed_values = [float(2 ** x) for x in range(-127, 128)]
diff --git a/bitstring/bitstream.py b/bitstring/bitstream.py
index 9a65360..fb32043 100644
--- a/bitstring/bitstream.py
+++ b/bitstring/bitstream.py
@@ -109,19 +109,25 @@ class ConstBitStream(Bits):

     def _setbytepos(self, bytepos: int) ->None:
         """Move to absolute byte-aligned position in stream."""
-        pass
+        if bytepos * 8 > len(self):
+            raise ValueError("Byte position out of range")
+        self._pos = bytepos * 8

     def _getbytepos(self) ->int:
         """Return the current position in the stream in bytes. Must be byte aligned."""
-        pass
+        if self._pos % 8:
+            raise ValueError("Current position is not byte aligned")
+        return self._pos // 8

     def _setbitpos(self, pos: int) ->None:
         """Move to absolute position bit in bitstream."""
-        pass
+        if pos < 0 or pos > len(self):
+            raise ValueError("Bit position out of range")
+        self._pos = pos

     def _getbitpos(self) ->int:
         """Return the current position in the stream in bits."""
-        pass
+        return self._pos

     def __copy__(self: TConstBitStream) ->TConstBitStream:
         """Return a new copy of the ConstBitStream for the copy module."""
@@ -184,7 +190,8 @@ class ConstBitStream(Bits):
         The current bit position will be moved to the end of the BitStream.

         """
-        pass
+        self._bitstore.append(Bits(bs)._bitstore)
+        self._pos = len(self)

     def __repr__(self) ->str:
         """Return representation that could be used to recreate the bitstring.
@@ -204,7 +211,18 @@ class ConstBitStream(Bits):
         Raises ValueError if pos < 0 or pos > len(self).

         """
-        pass
+        if pos is None:
+            pos = self._pos
+        if pos < 0 or pos > len(self):
+            raise ValueError("pos must be between 0 and len(self)")
+        
+        bs = Bits(bs)
+        end = pos + len(bs)
+        if end > len(self):
+            self._bitstore.append(bs._bitstore)
+        else:
+            self._bitstore[pos:end] = bs._bitstore
+        self._pos = end

     def find(self, bs: BitsType, /, start: Optional[int]=None, end:
         Optional[int]=None, bytealigned: Optional[bool]=None) ->Union[Tuple
@@ -229,7 +247,24 @@ class ConstBitStream(Bits):
         (6,)

         """
-        pass
+        bs = Bits(bs)
+        if not bs:
+            raise ValueError("Cannot find an empty bitstring")
+        
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+        
+        if start < 0 or end > len(self) or end < start:
+            raise ValueError("Invalid start or end values")
+        
+        if bytealigned:
+            start = (start + 7) // 8 * 8
+        
+        pos = self._bitstore.find(bs._bitstore, start, end, bytealigned)
+        if pos >= 0:
+            self._pos = pos
+            return (pos,)
+        return ()

     def rfind(self, bs: BitsType, /, start: Optional[int]=None, end:
         Optional[int]=None, bytealigned: Optional[bool]=None) ->Union[Tuple
@@ -251,7 +286,24 @@ class ConstBitStream(Bits):
         if end < start.

         """
-        pass
+        bs = Bits(bs)
+        if not bs:
+            raise ValueError("Cannot find an empty bitstring")
+        
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+        
+        if start < 0 or end > len(self) or end < start:
+            raise ValueError("Invalid start or end values")
+        
+        if bytealigned:
+            start = (start + 7) // 8 * 8
+        
+        pos = self._bitstore.rfind(bs._bitstore, start, end, bytealigned)
+        if pos >= 0:
+            self._pos = pos
+            return (pos,)
+        return ()

     def read(self, fmt: Union[int, str, Dtype]) ->Union[int, float, str,
         Bits, bool, bytes, None]:
@@ -290,7 +342,19 @@ class ConstBitStream(Bits):
         Raises ValueError if the format is not understood.

         """
-        pass
+        if isinstance(fmt, int):
+            fmt = f'bits:{fmt}'
+        
+        dtype = Dtype(fmt)
+        length = dtype.length
+        
+        if self._pos + length > len(self):
+            raise bitstring.ReadError("Not enough bits available")
+        
+        value = dtype.get_fn(self[self._pos:self._pos + length])
+        self._pos += length
+        
+        return value

     def readlist(self, fmt: Union[str, List[Union[int, str, Dtype]]], **kwargs
         ) ->List[Union[int, float, str, Bits, bool, bytes, None]]:
@@ -314,7 +378,23 @@ class ConstBitStream(Bits):
         >>> i, bs1, bs2 = s.readlist(['uint:12', 10, 10])

         """
-        pass
+        tokens = []
+        if isinstance(fmt, str):
+            fmt = fmt.replace(' ', '')
+            tokens = fmt.split(',')
+        elif isinstance(fmt, list):
+            tokens = fmt
+        else:
+            raise ValueError("fmt must be either a string or a list")
+
+        return_values = []
+        for token in tokens:
+            if isinstance(token, int):
+                token = f'bits:{token}'
+            value = self.read(token)
+            if not token.startswith('pad:'):
+                return_values.append(value)
+        return return_values

     def readto(self: TConstBitStream, bs: BitsType, /, bytealigned:
         Optional[bool]=None) ->TConstBitStream:
@@ -328,7 +408,18 @@ class ConstBitStream(Bits):
         Raises ReadError if bs is not found.

         """
-        pass
+        bs = Bits(bs)
+        if not bs:
+            raise ValueError("Cannot find an empty bitstring")
+
+        found = self.find(bs, start=self._pos, bytealigned=bytealigned)
+        if not found:
+            raise bitstring.ReadError("Substring not found")
+
+        end = found[0] + len(bs)
+        return_value = self[self._pos:end]
+        self._pos = end
+        return return_value

     def peek(self: TConstBitStream, fmt: Union[int, str]) ->Union[int,
         float, str, TConstBitStream, bool, bytes, None]:
@@ -345,7 +436,11 @@ class ConstBitStream(Bits):
         See the docstring for 'read' for token examples.

         """
-        pass
+        original_pos = self._pos
+        try:
+            return self.read(fmt)
+        finally:
+            self._pos = original_pos

     def peeklist(self, fmt: Union[str, List[Union[int, str]]], **kwargs
         ) ->List[Union[int, float, str, Bits, None]]:
@@ -537,7 +632,9 @@ class BitStream(ConstBitStream, bitstring.BitArray):
         bs -- The bitstring to prepend.

         """
-        pass
+        bs = Bits(bs)
+        self._bitstore = bs._bitstore + self._bitstore
+        self._pos += len(bs)

     def __setitem__(self, /, key: Union[slice, int], value: BitsType) ->None:
         length_before = len(self)
@@ -570,7 +667,14 @@ class BitStream(ConstBitStream, bitstring.BitArray):
         Raises ValueError if pos < 0 or pos > len(self).

         """
-        pass
+        if pos is None:
+            pos = self._pos
+        if pos < 0 or pos > len(self):
+            raise ValueError("pos must be between 0 and len(self)")
+        
+        bs = Bits(bs)
+        self._bitstore = self._bitstore[:pos] + bs._bitstore + self._bitstore[pos:]
+        self._pos = pos + len(bs)

     def replace(self, old: BitsType, new: BitsType, start: Optional[int]=
         None, end: Optional[int]=None, count: Optional[int]=None,
@@ -594,4 +698,29 @@ class BitStream(ConstBitStream, bitstring.BitArray):
         out of range.

         """
-        pass
+        old = Bits(old)
+        new = Bits(new)
+        if not old:
+            raise ValueError("Cannot replace an empty bitstring")
+        
+        start = 0 if start is None else start
+        end = len(self) if end is None else end
+        count = -1 if count is None else count
+        
+        if start < 0 or end > len(self) or start > end:
+            raise ValueError("Invalid start or end values")
+        
+        replacements = 0
+        pos = start
+        while count != 0:
+            found = self.find(old, start=pos, end=end, bytealigned=bytealigned)
+            if not found:
+                break
+            pos = found[0]
+            self._bitstore = self._bitstore[:pos] + new._bitstore + self._bitstore[pos + len(old):]
+            pos += len(new)
+            end += len(new) - len(old)
+            replacements += 1
+            count -= 1
+        
+        return replacements
diff --git a/bitstring/dtypes.py b/bitstring/dtypes.py
index 775063f..09100af 100644
--- a/bitstring/dtypes.py
+++ b/bitstring/dtypes.py
@@ -44,57 +44,57 @@ class Dtype:
     @property
     def scale(self) ->Union[int, float, None]:
         """The multiplicative scale applied when interpreting the data."""
-        pass
+        return self._scale

     @property
     def name(self) ->str:
         """A string giving the name of the data type."""
-        pass
+        return self._name

     @property
     def length(self) ->int:
         """The length of the data type in units of bits_per_item. Set to None for variable length dtypes."""
-        pass
+        return self._length

     @property
     def bitlength(self) ->Optional[int]:
         """The number of bits needed to represent a single instance of the data type. Set to None for variable length dtypes."""
-        pass
+        return self._bitlength

     @property
     def bits_per_item(self) ->int:
         """The number of bits for each unit of length. Usually 1, but equals 8 for bytes type."""
-        pass
+        return self._bits_per_item

     @property
     def variable_length(self) ->bool:
         """If True then the length of the data type depends on the data being interpreted, and must not be specified."""
-        pass
+        return self._variable_length

     @property
     def return_type(self) ->Any:
         """The type of the value returned by the parse method, such as int, float or str."""
-        pass
+        return self._return_type

     @property
     def is_signed(self) ->bool:
         """If True then the data type represents a signed quantity."""
-        pass
+        return self._is_signed

     @property
     def set_fn(self) ->Optional[Callable]:
         """A function to set the value of the data type."""
-        pass
+        return self._set_fn

     @property
     def get_fn(self) ->Callable:
         """A function to get the value of the data type."""
-        pass
+        return self._get_fn

     @property
     def read_fn(self) ->Callable:
         """A function to read the value of the data type."""
-        pass
+        return self._read_fn

     def __hash__(self) ->int:
         return hash((self._name, self._length))
@@ -104,13 +104,31 @@ class Dtype:

         The value parameter should be of a type appropriate to the dtype.
         """
-        pass
+        if self._set_fn is None:
+            raise NotImplementedError(f"Cannot build {self._name} dtype")
+        
+        if self._set_fn_needs_length:
+            return self._set_fn(value, self._length)
+        else:
+            return self._set_fn(value)

     def parse(self, b: BitsType, /) ->Any:
         """Parse a bitstring to find its value.

         The b parameter should be a bitstring of the appropriate length, or an object that can be converted to a bitstring."""
-        pass
+        if isinstance(b, bitstring.Bits):
+            bs = b
+        else:
+            bs = bitstring.Bits(b)
+        
+        if not self._variable_length and self._bitlength is not None:
+            if len(bs) != self._bitlength:
+                raise ValueError(f"Expected {self._bitlength} bits, got {len(bs)}")
+        
+        result = self._get_fn(bs)
+        if self._scale is not None:
+            return result * self._scale
+        return result

     def __str__(self) ->str:
         if self._scale is not None:
diff --git a/bitstring/fp8.py b/bitstring/fp8.py
index 4cf9431..53453e9 100644
--- a/bitstring/fp8.py
+++ b/bitstring/fp8.py
@@ -25,11 +25,61 @@ class Binary8Format:

     def float_to_int8(self, f: float) ->int:
         """Given a Python float convert to the best float8 (expressed as an integer in 0-255 range)."""
-        pass
+        if math.isnan(f):
+            return 0  # NaN is represented as 0 in this format
+        
+        if f == 0:
+            return 0 if math.copysign(1, f) == 1 else 128  # Handle +0 and -0
+        
+        if f > 0 and f >= 2 ** (self.pos_clamp_value - self.bias):
+            return self.pos_clamp_value  # Positive infinity or too large positive number
+        
+        if f < 0 and f <= -2 ** (self.neg_clamp_value - 128 - self.bias):
+            return self.neg_clamp_value  # Negative infinity or too large negative number
+        
+        sign = 0 if f > 0 else 128
+        f = abs(f)
+        
+        exponent = math.floor(math.log2(f)) + self.bias
+        mantissa = round((f / (2 ** (exponent - self.bias)) - 1) * (2 ** (8 - self.exp_bits)))
+        
+        if mantissa == 2 ** (8 - self.exp_bits):
+            exponent += 1
+            mantissa = 0
+        
+        if exponent < 0:
+            exponent = 0
+            mantissa = 1
+        elif exponent >= 2 ** self.exp_bits - 1:
+            exponent = 2 ** self.exp_bits - 1
+            mantissa = 0
+        
+        return sign | (exponent << (8 - self.exp_bits)) | mantissa

     def createLUT_for_binary8_to_float(self):
         """Create a LUT to convert an int in range 0-255 representing a float8 into a Python float"""
-        pass
+        lut = []
+        for i in range(256):
+            sign = -1 if i & 128 else 1
+            exponent = (i >> (8 - self.exp_bits)) & ((1 << self.exp_bits) - 1)
+            mantissa = i & ((1 << (8 - self.exp_bits)) - 1)
+            
+            if exponent == 0:
+                if mantissa == 0:
+                    value = 0.0
+                else:
+                    value = sign * (mantissa / (2 ** (8 - self.exp_bits))) * (2 ** (1 - self.bias))
+            elif exponent == (2 ** self.exp_bits) - 1:
+                if mantissa == 0:
+                    value = float('inf') if sign == 1 else float('-inf')
+                else:
+                    value = float('nan')
+            else:
+                value = sign * (1 + mantissa / (2 ** (8 - self.exp_bits))) * (2 ** (exponent - self.bias))
+            
+            lut.append(value)
+        
+        return lut


 p4binary_fmt = Binary8Format(exp_bits=4, bias=8)
diff --git a/bitstring/methods.py b/bitstring/methods.py
index e6be89b..db7277d 100644
--- a/bitstring/methods.py
+++ b/bitstring/methods.py
@@ -43,4 +43,37 @@ def pack(fmt: Union[str, List[str]], *values, **kwargs) ->BitStream:
     >>> u = pack('uint:8=a, uint:8=b, uint:55=a', a=6, b=44)

     """
-    pass
+    if isinstance(fmt, list):
+        fmt = ','.join(fmt)
+
+    tokens, _ = tokenparser(fmt)
+    bitstring_list = []
+    value_index = 0
+
+    for token in tokens:
+        if '=' in token[1]:
+            name, token_str = token[1].split('=')
+            value = kwargs.get(name.strip())
+            if value is None:
+                raise CreationError(f"Keyword '{name.strip()}' not provided")
+        else:
+            if value_index >= len(values):
+                raise CreationError("Not enough values provided")
+            value = values[value_index]
+            value_index += 1
+            token_str = token[1]
+
+        try:
+            bs = bitstore_from_token(token_str, value)
+            bitstring_list.append(bs)
+        except ValueError as e:
+            raise CreationError(str(e))
+
+    if value_index < len(values):
+        raise CreationError("Too many values provided")
+
+    result = BitStream()
+    for bs in bitstring_list:
+        result.append(bs)
+
+    return result
diff --git a/bitstring/mxfp.py b/bitstring/mxfp.py
index be90cd1..9afdd75 100644
--- a/bitstring/mxfp.py
+++ b/bitstring/mxfp.py
@@ -42,15 +42,66 @@ class MXFPFormat:

     def float_to_int(self, f: float) ->int:
         """Given a Python float convert to the best mxfp float (expressed as an int) that represents it."""
-        pass
+        if math.isnan(f):
+            return (1 << (self.exp_bits + self.mantissa_bits + 1)) - 1  # All ones for NaN
+        
+        if f == 0:
+            return 0  # Zero is represented as all zeros
+        
+        sign = 1 if f < 0 else 0
+        f = abs(f)
+        
+        # Handle infinity and large numbers
+        if math.isinf(f) or f >= 2 ** (2 ** self.exp_bits - self.bias):
+            if self.mxfp_overflow == 'saturate':
+                return self.neg_clamp_value if sign else self.pos_clamp_value
+            else:  # overflow
+                return self.neg_clamp_value if sign else self.pos_clamp_value
+        
+        # Find the exponent
+        exp = math.floor(math.log2(f))
+        exp = max(exp, 1 - self.bias)  # Handle subnormals
+        
+        # Calculate mantissa
+        mantissa = int(round((f / (2 ** exp) - 1) * (2 ** self.mantissa_bits)))
+        
+        # Adjust for bias
+        exp += self.bias
+        
+        # Combine sign, exponent, and mantissa
+        result = (sign << (self.exp_bits + self.mantissa_bits)) | (exp << self.mantissa_bits) | mantissa
+        
+        return result

     def createLUT_for_int_to_float(self) ->array.array:
         """Create a LUT to convert an int in representing a MXFP float into a Python float"""
-        pass
+        lut = array.array('f')
+        for i in range(1 << (self.exp_bits + self.mantissa_bits + 1)):
+            sign = -1 if i & (1 << (self.exp_bits + self.mantissa_bits)) else 1
+            exp = (i >> self.mantissa_bits) & ((1 << self.exp_bits) - 1)
+            mantissa = i & ((1 << self.mantissa_bits) - 1)
+            
+            if exp == 0 and mantissa == 0:
+                lut.append(0.0)
+            elif exp == (1 << self.exp_bits) - 1:
+                if mantissa == 0:
+                    lut.append(float('inf') if sign > 0 else float('-inf'))
+                else:
+                    lut.append(float('nan'))
+            else:
+                value = sign * (1 + mantissa / (2 ** self.mantissa_bits)) * (2 ** (exp - self.bias))
+                lut.append(value)
+        
+        return lut

     def createLUT_for_float16_to_mxfp(self) ->bytes:
         """Create a LUT to convert a float16 into a MXFP format"""
-        pass
+        lut = bytearray(65536)
+        for i in range(65536):
+            f16 = struct.unpack('!e', struct.pack('!H', i))[0]
+            mxfp = self.float_to_int(f16)
+            lut[i] = mxfp
+        return bytes(lut)


 e2m1mxfp_fmt = MXFPFormat(exp_bits=2, mantissa_bits=1, bias=1,
diff --git a/bitstring/utils.py b/bitstring/utils.py
index 623d69b..dd9fa5a 100644
--- a/bitstring/utils.py
+++ b/bitstring/utils.py
@@ -36,7 +36,27 @@ PACK_CODE_SIZE: Dict[str, int] = {'b': 1, 'B': 1, 'h': 2, 'H': 2, 'l': 4,

 def structparser(m: Match[str]) ->List[str]:
     """Parse struct-like format string token into sub-token list."""
-    pass
+    endian = m.group('endian')
+    fmt = m.group('fmt')
+    tokens = []
+    
+    if endian == '>':
+        replacements = REPLACEMENTS_BE
+    elif endian == '<':
+        replacements = REPLACEMENTS_LE
+    else:
+        replacements = REPLACEMENTS_NE
+    
+    for match in STRUCT_SPLIT_RE.finditer(fmt):
+        code = match.group()
+        if code[0] in '0123456789':
+            count = int(code[:-1])
+            token = replacements[code[-1]]
+            tokens.extend([token] * count)
+        else:
+            tokens.append(replacements[code])
+    
+    return tokens


 @functools.lru_cache(CACHE_SIZE)
@@ -54,7 +74,61 @@ def tokenparser(fmt: str, keys: Tuple[str, ...]=()) ->Tuple[bool, List[
     tokens must be of the form: [factor*][initialiser][:][length][=value]

     """
-    pass
+    tokens = []
+    stretchy_token = False
+    fmt = expand_brackets(fmt)
+    
+    for token in fmt.split(','):
+        token = token.strip()
+        if token in keys:
+            tokens.append((token, None, None))
+            continue
+        
+        mobj = MULTIPLICATIVE_RE.match(token)
+        if mobj:
+            factor = int(mobj.group('factor'))
+            token = mobj.group('token')
+        else:
+            factor = 1
+        
+        mobj = NAME_INT_RE.match(token)
+        if mobj:
+            name, length = mobj.group(1), mobj.group(2)
+            if length:
+                length = int(length)
+            else:
+                length = None
+            if name == 'pad':
+                if length is None:
+                    stretchy_token = True
+            tokens.extend([(name, length, None)] * factor)
+            continue
+        
+        mobj = DEFAULT_BITS.match(token)
+        if mobj:
+            name = 'bits'
+            length = mobj.group('len')
+            if length:
+                length = int(length)
+            else:
+                length = None
+            value = mobj.group('value')
+            if length is None and value is None:
+                stretchy_token = True
+            tokens.extend([(name, length, value)] * factor)
+            continue
+        
+        mobj = LITERAL_RE.match(token)
+        if mobj:
+            name = mobj.group('name').lower()
+            value = mobj.group('value')
+            length = len(value) * {'0b': 1, '0o': 3, '0x': 4}[name]
+            tokens.extend([(name, length, value)] * factor)
+            continue
+        
+        raise ValueError(f"Don't understand token '{token}' in format string")
+    
+    return stretchy_token, tokens


 BRACKET_RE = re.compile('(?P<factor>\\d+)\\*\\(')
@@ -62,4 +136,13 @@ BRACKET_RE = re.compile('(?P<factor>\\d+)\\*\\(')

 def expand_brackets(s: str) ->str:
     """Expand all brackets."""
-    pass
+    while True:
+        match = BRACKET_RE.search(s)
+        if not match:
+            break
+        factor = int(match.group('factor'))
+        start = match.start()
+        end = s.index(')', start)
+        sub = s[start + len(match.group()):end]
+        s = s[:start] + ','.join([sub] * factor) + s[end + 1:]
+    return s