- Upgraded bitarray dependency to >= 3.0.0.
- Explicit support for Python 3.13.
- Fix for LSB0 slicing issue. Bug #343.
- Some codes representing exotic float negative zero converted to positive zero. Bug #333.
- Auto-scaling rounding the wrong way on occasion. Bug #334.
- Sometimes a
ValueErrorwas being raised instead of aReadError. Bug #325. - Initialising a bitstring from
Nonenow raises aTypeErrorrather than generating an empty bitstring. Bug #323. - Fixed performance regression for
find/findallin some situations. Bug #326. - Fix for
AttributeErrorbug when combiningBitswithBitStream. Bug #329.
- Module crashes on import with 32-bit Python. Bug #317.
- Lists of integers not converted to bytes when using the bytes constructor. Bug #318.
- Empty comma separated tokens not handled correctly. Bug #319.
- Crash on import when docstrings not present due to optimize flag. Bug #321.
This release contains a fairly large refactor of how different types are managed. This shouldn't affect the end user, and the main noticeable change should be the new Dtype class, which is optional to use.
Support for 8-bit and smaller floats has been reworked and expanded. These are still a 'beta' feature.
- Dropped support for Python 3.7. Minimum version is now 3.8.
- For tokens that use a non-numeric length, a
':'is now compulsory rather than recommended. For example use'uint:foo'instead of'uintfoo'. - The previous
e4m3floatande5m2floatformats have become the slightly modifiedp4binary8andp3binary8formats. - Some parameters are now enforced as positional only, such as
autoin constructors.
-
The
Arrayclass is no longer 'beta'. -
A new
Dtypeclass can be optionally used to specify types. -
The
bitstring.optionsobject is now the preferred method for changing module options. Thebitstring.lsb0andbitstring.bytealignedvariables are now deprecated, usebitstring.options.lsb0andbitstring.options.bytealignedinstead. -
New
fromstringmethod as another way to create bitstrings from formatted strings. Instead of relying on theautoparameter you can now optionally usefromstring.>>> s1 = BitArray('u24=1000') # This is still fine. >>> s2 = BitArray.fromstring('u24=1000') # This may be clearer and more efficient.
-
More types can now be pretty printed. For example integer and float formats can be used.
>>> s.pp('u15, bin') -
Pretty printing is now prettier - optional terminal colours added.
-
A range of 8-bit, 6-bit and even 4-bit float formats added (beta):
p3binary8: IEEE 8-bit floating point with 3 bit precision.p4binary8: IEEE 8-bit floating point with 4 bit precision.e5m2mxfp: OCP 8-bit floating point with 3 bit precision.e4m3mxfp: OCP 8-bit floating point with 4 bit precision.e2m3mxfp: OCP 6-bit floating point with 4 bit precision.e3m2mxfp: OCP 6-bit floating point with 3 bit precision.e2m1mxfp: OCP 4-bit floating point with 2 bit precision.e8m0mxfp: OCP 8-bit unsigned floating point designed to scale the other formats.mxint: OCP 8-bit floating point that is a scaled integer representation.
-
Performance improvements.
Fixing a regression introduced in 4.1.3
'bytes'token can't be used without explicit length. Bug #303.
A maintenance release, with some changes to the beta features introduced in 4.1.
- Removed a couple of files that accidentally got included in the previous release. Bug #293.
- The 8-bit float formats have been renamed
e4m3floatande5m2float. - Some refactoring and performance optimizations.
Another maintenance release. Once again some small changes to the 'beta' Array class,
plus new Array functionality.
- Fix for the module command-line usage. Bug #290.
- Fix for when creating bitstrings from
memoryviewobjects. - Renamed the
fmtparameter for Arrays todtype. - More Array operator coverage.
- Added operators that act on two Arrays of the same size.
- Added comparison operators for Arrays that return an Array of bools.
- Added
Array.equalsmethod as==will now return anArray(see above item). - Added
astype()method for Arrays to easily cast to a new dtype.
A maintenance release, with some changes to the Array class which is still in beta.
- bitarray dependency now pinned to
">=2.8.0, <3.0.0"rather than a specific version. Bug #283. - Fix for using numpy integers as integer parameters. Bug #286.
- Removed ability to extend an Array with the
+operator. Use theextendmethod instead. - Improvements when pretty-printing the Array.
Array.count()can now countfloat('nan')values for floating point types.
This has turned into a surprisingly big release, with a major refactor and a brand-new class (the first for 12 years!)
There are also a couple of small possibly breaking changes detailed below, in particular 'auto' initialising bitstrings from integers is now disallowed.
The major weakness of bitstring has been its poor performance for computationally intensive tasks relative to lower level alternatives. This was principally due to relying on pure Python code to achieve things that the base language often didn't have fast ways of doing.
This release starts to address that problem with a fairly extensive rewrite to replace much of the pure Python low-level bit operations with methods from the bitarray package. This is a package that does many of the same things as bitstring, and the two packages have co-existed for a long time. While bitarray doesn't have all of the options and facilities of bitstring it has the advantage of being very fast as it is implemented in C. By replacing the internal datatypes I can speed up bitstring's operations while keeping the same API.
Huge kudos to Ilan Schnell for all his work on bitarray.
If your data is all of a single type you can make use of the new Array class, which
mirrors much of the functionality of the standard array.array type, but doesn't restrict
you to just a dozen formats.
>>> from bitstring import Array
>>> a = Array('uint7', [9, 100, 3, 1])
>>> a.data
BitArray('0x1390181')
>>> b = Array('float16', a.tolist())
>>> b.append(0.25)
>>> b.tobytes()
b'H\x80V@B\x00<\x004\x00'
>>> b.tolist()
[9.0, 100.0, 3.0, 1.0, 0.25]The data is stored efficiently in a BitArray object, and you can manipulate both the
data and the Array format freely. See the main documentation for more details. Note that
this feature carries the 'beta' flag so may change in future point versions.
-
Added two new floating point interpretations:
float8_143andfloat8_152. These are 8-bit floating point formats, with very limited range and precision, but useful in some fields, particularly machine learning. This is an experimental feature - the formats haven't even been standardised yet.>>> a = Bits(float8_143=16.5) >>> a.bin '01100000' >>> a.float8_143 16.0
-
Auto initialization from ints has been removed and now raises a
TypeError. Creating a bitstring from an int still creates a zeroed bitstring of that length but ints won't be promoted to bitstrings as that has been a constant source of errors and confusion.>>> a = BitArray(100) # Fine - create with 100 zeroed bits >>> a += 0xff # TypeError - previously this would have appended 0xff (=255) zero bits. >>> a += '0xff' # Probably what was meant - append eight '1' bits. >>> a += Bits(255) # Fine, append 255 zero bits.
This is a breaking change, but it breaks loudly with an exception, it is easily recoded, and it removes a confusing wrinkle.
-
Explicitly specifying the
autoparameter is now disallowed rather than discouraged. It was always meant to be a positional-only parameter (and will be once I can drop Python 3.7 support) but for now it's renamed to__auto. In the unlikely event this breaks code, the fix should be just to delete theauto=if it's already the first parameter.>>> s = Bits(auto='0xff') # Now raises a CreationError >>> s = Bits('0xff') # Fine, as always
-
Deleting, replacing or inserting into a bitstring resets the bit position to 0 if the bitstring's length has been changed. Previously the bit position was adjusted but this was not well-defined.
-
Only empty bitstring are now considered false in a boolean sense. Previously
swasFalseif no bits inswere set to1, but this goes against what it means to be a container in Python, so I consider this to be a bug, even if it was documented. I'm guessing it's related to__nonzero__in Python 2 becoming__bool__in Python 3, and it's never been fixed before now. -
Casting to
bytesnow behaves as expected, so thatbytes(s)gives the same result ass.tobytes(). Previously it created a byte per bit. -
Pretty printing with the
'bytes'format now uses characters from the 'Latin Extended-A' unicode block for non-ASCII and unprintable characters instead of replacing them with'.' -
When using struct-like codes you can now use
'='instead of'@'to signify native- endianness. They behave identically, but the new'='is now preferred. -
More fixes for LSB0 mode. There are now no known issues with this feature.
- Added
py.typedfile and converted the module to a package to let mypy find type annotations. Bug 248. - Fix to shifting operations when using LSB0 mode. Bug 251.
- A few more fixes for LSB0 mode.
- Improved LSB0 documentation.
- Added build-system section to
pyproject.toml. Bug 243. - Rewrote the walkthrough documentation as a jupyter notebook.
- Updated the project's logo.
This is a major release which drops support for Python 2.7 and has a new minimum requirement of Python 3.7. Around 95% of downloads satisfy this - users of older versions can continue to use bitstring 3.1, which will still be supported with fixes, but no new features.
Other breaking changes are minimal, and there are a few cool features added.
- Minimum supported Python version is now Python 3.7.
- Removed
ConstBitArrayandBitStringclass aliases. UseBitsandBitStreaminstead. - The
cut()method will now also yield the final bits of a bitstring, even if they are shorter than the requested cut size. - Removed default
uintinterpretation. This wasn't being applied uniformly - the default is now always to return a bitstring object of the given length and not to interpret it as auint. Bug 220. - If an overwrite goes beyond the end of the bitstring it will now extend the bitstring rather than raise an exception. Bug 148.
-
Type hints added throughout the code.
-
Underscores are now allowed in strings representing number literals.
-
The
copy()method now works onBitsas well asBitArrayobjects. -
The experimental command-line feature is now official. Command-line parameters are concatenated and a bitstring created from them. If the final parameter is either an interpretation string or ends with a
'.'followed by an interpretation string then that interpretation of the bitstring will be used when printing it.$ python -m bitstring int:16=-400 0xfe70 $ python -m bitstring float:32=0.2 bin 00111110010011001100110011001101
-
New
pp()method that pretty-prints the bitstring in various formats - useful especially in interactive sessions. Thanks to Omer Barak for the suggestion and discussion.>>> s.pp() 0: 10001000 01110110 10001110 01110110 11111000 01110110 10000111 00101000 64: 01110010 11111001 10000111 10011000 11110111 10011110 10000111 11111101 128: 11111001 10001100 01111111 10111100 10111111 11011011 11101011 11111011 192: 1100 >>> s.pp('bin, hex') 0: 10001000 01110110 10001110 01110110 11111000 01110110 88 76 8e 76 f8 76 48: 10000111 00101000 01110010 11111001 10000111 10011000 87 28 72 f9 87 98 96: 11110111 10011110 10000111 11111101 11111001 10001100 f7 9e 87 fd f9 8c 144: 01111111 10111100 10111111 11011011 11101011 11111011 7f bc bf db eb fb 192: 1100 c -
Shorter and more versatile properties. The
bin,oct,hex,float,uintandintproperties can now be shortened to just their first letter. They can also have a length in bits after them - allowing Rust-like data types.>>> s = BitArray('0x44961000') >>> s.h '44961000' >>> s.f32 1200.5 >>> s.u 1150685184 >>> s.i7 = -60 >>> s.b '1000100' >>> t = Bits('u12=160, u12=120, b=100')
-
Other types with bit lengths can also be used as properties:
>>> s.floatle64 = 10.511
-
A colon is no longer required in format strings before a bit length. So for example
Bits('int:15=-101')could be written asBits('int15=-101'). This is now the preferred usage in the documentation except where the colon improves readability. -
Support for IEEE 16 bit floats. Floating point types can now be 16 bits long as well as 32 and 64 bits. This is using the
'e'format from the struct module. -
Support for bfloats. This is a specialised 16-bit floating point format mostly used in machine learning. It's essentially a truncated IEEE 32-bit format that keeps its range but only has a couple of significant figures of accuracy.
(version 3.1.8 was pulled due to serious issues) Another maintenance release.
- Fixed a couple of outdated results in the readme (Issue 214).
- Some more documentation tidying.
- Turned off some debug code by default.
- Fixed a couple of failing tests in different Python versions.
- Fix for consistent pos initialisation semantics for different types.
- Change to allow wheels to be uploaded to PyPI.
- More work for LSB0 mode, but still not finished or documented (sorry).
This is a maintenance release with a few bug fixes plus an experimental feature to allow bits to be indexed in the opposite direction.
- Fixing del not working correctly when stop value negative (Issue 201)
- Removed deprecated direct import of ABC from collections module (Issue 196)
- Tested and added explicit support for Python 3.7 and 3.8. (Issue 193)
- Fixing a few stale links to documentation. (Issue 194)
- Allowing initialisation with an io.BytesIO object. (Issue 189)
This feature allows bitstring to use Least Significant Bit Zero
(LSB0) bit numbering; that is the final bit in the bitstring will
be bit 0, and the first bit will be bit (n-1), rather than the
other way around. LSB0 is a more natural numbering
system in many fields, but is the opposite to Most Significant Bit
Zero (MSB0) numbering which is the natural option when thinking of
bitstrings as standard Python containers.
To switch from the default MSB0, use the module level function
>>> bitstring.set_lsb0(True)Getting and setting bits should work in this release, as will some other methods. Many other methods are not tested yet and might not work as expected. This is mostly a release to get feedback before finalising the interface.
Slicing is still done with the start bit smaller than the end bit. For example:
>>> s = Bits('0b000000111')
>>> s[0:5]
Bits('0b00111')
>>> s[0]
TrueNegative indices work as (hopefully) you'd expect, with the first stored
bit being s[-1] and the final stored bit being s[-n].
See #156 for discussions and to add any further comments.
A long overdue maintenance release with some fixes.
- Fixed immutability bug. Bug 176.
- Fixed failure of
__contains__in some circumstances. Bug 180. - Better handling of open files. Bug 186.
- Better Python 2/3 check.
- Making unit tests easier to run.
- Allowing length of 1 to be specified for bools. (Thanks to LemonPi)
- Support initialisation from an array.
- Added a separate LICENSE file.
This is another bug fix release.
- Fix for bitstring types when created directly from other bitstring types.
- Updating contact, website details.
This is another bug fix release.
- Fix for problem with prepend for bitstrings with byte offsets in their data store.
This is another bug fix release.
- Fix for problem where unpacking bytes would by eight times too long
This is a bug fix release.
- Fix for problem where concatenating bitstrings sometimes modified method's arguments
This is a minor release with a couple of new features and some bug fixes.
This token can be used in reads and when packing/unpacking to indicate that you don't care about the contents of these bits. Any padding bits will just be skipped over when reading/unpacking or zero-filled when packing.
>>> a, b = s.readlist('pad:5, uint:3, pad:1, uint:3')Here only two items are returned in the list - the padding bits are ignored.
These methods have been introduced in Python 3.3 for lists and bytearrays, as more obvious ways of clearing and copying, and we mirror that change here.
t = s.copy() is equivalent to t = s[:], and s.clear() is equivalent to del s[:].
- Some bug fixes.
This is a minor update that fixes a few bugs.
- Fix for subclasses of bitstring classes behaving strangely (Issue 121).
- Fix for excessive memory usage in rare cases (Issue 120).
- Fixes for slicing edge cases.
There has also been a reorganisation of the code to return it to a single
bitstring.py file rather than the package that has been used for the past
several releases. This change shouldn't affect users directly.
This release fixed a small but very visible bug in bitstring printing.
This is a major release which breaks backward compatibility in a few places.
If you ask for the hex, octal or binary representations of a bitstring then
they will no longer be prefixed with '0x', '0o' or '0b'. This was done as it
was noticed that the first thing a lot of user code does after getting these
representations was to cut off the first two characters before further
processing.
>>> a = BitArray('0x123')
>>> a.hex, a.oct, a.bin
('123', '0443', '000100100011')Previously this would have returned ('0x123', '0o0443', '0b000100100011')
This change might require some recoding, but it should all be simplifications.
Previously Bits was an alias for ConstBitStream (for backward compatibility).
This has now changed so that Bits and BitArray loosely correspond to the
built-in types bytes and bytearray.
If you were using streaming/reading methods on a Bits object then you will
have to change it to a ConstBitStream.
The ConstBitArray name is kept as an alias for Bits.
The step parameter in __getitem__, __setitem__ and __delitem__ used to act
as a multiplier for the start and stop parameters. No one seemed to use it
though and so it has now reverted to the conventional meaning for containers.
If you are using step then recoding is simple: s[a:b:c] becomes s[a*c:b*c].
Some examples of the new usage:
>>> s = BitArray('0x0000')
s[::4] = [1, 1, 1, 1]
>>> s.hex
'8888'
>>> del s[8::2]
>>> s.hex
'880'This method is a mix between a find and a read - it searches for a bitstring and then reads up to and including it. For example:
>>> s = ConstBitStream('0x47000102034704050647')
>>> s.readto('0x47', bytealigned=True)
BitStream('0x47')
>>> s.readto('0x47', bytealigned=True)
BitStream('0x0001020347')
>>> s.readto('0x47', bytealigned=True)
BitStream('0x04050647')Previously only a string was accepted as the format in the pack function.
This was an oversight as it broke the symmetry between pack and unpack.
Now you can use formats like this:
fmt = ['hex:8', 'bin:3']
a = pack(fmt, '47', '001')
a.unpack(fmt)This is a minor upgrade with a couple of new features.
New bit interpretations for interleaved exponential-Golomb (as used in the
Dirac video codec) are supplied via uie and sie:
>>> s = BitArray(uie=41)
>>> s.uie
41
>>> s.bin
'0b00010001001'These are pretty similar to the non-interleaved versions - see the manual for more details. Credit goes to Paul Sargent for the patch.
A number of methods take a bytealigned parameter to indicate that they
should only work on byte boundaries (e.g. find, replace, split). Previously
this parameter defaulted to False. Instead, it now defaults to
bitstring.bytealigned, which itself defaults to False, but can be changed
to modify the default behaviour of the methods. For example:
>>> a = BitArray('0x00 ff 0f ff')
>>> a.find('0x0f')
(4,) # found first not on a byte boundary
>>> a.find('0x0f', bytealigned=True)
(16,) # forced looking only on byte boundaries
>>> bitstring.bytealigned = True # Change default behaviour
>>> a.find('0x0f')
(16,)
>>> a.find('0x0f', bytealigned=False)
(4,)If you're only working with bytes then this can help avoid some errors and save some typing!
- Fix for Python 3.2, correcting for a change to the binascii module.
- Fix for bool initialisation from 0 or 1.
- Efficiency improvements, including interning strategy.
This is a release to fix a couple of bugs that were introduced in 2.1.0.
- Bug fix: Reading using the
'bytes'token had been broken (Issue 102). - Fixed problem using some methods on
ConstBitArrays. - Better exception handling for tokens missing values.
- Some performance improvements.
Previously there were just two classes, the immutable Bits which was the base
class for the mutable BitString class. Both of these classes have the concept
of a bit position, from which reads etc. take place so that the bitstring could
be treated as if it were a file or stream.
Two simpler classes have now been added which are purely bit containers and
don't have a bit position. These are called ConstBitArray and BitArray. As you
can guess the former is an immutable version of the latter.
The other classes have also been renamed to better reflect their capabilities.
Instead of BitString you can use BitStream, and instead of Bits you can use
ConstBitStream. The old names are kept as aliases for backward compatibility.
The classes hierarchy is:
ConstBitArray
/ \
/ \
BitArray ConstBitStream (formerly Bits)
\ /
\ /
BitStream (formerly BitString)
A lot of internal reorganisation has taken place since the previous version, most of which won't be noticed by the end user. Some things you might see are:
- New package structure. Previous versions have been a single file for the
module and another for the unit tests. The module is now split into many
more files so it can't be used just by copying
bitstring.pyany more. - To run the unit tests there is now a script called
runtests.pyin the test directory. - File based bitstring are now implemented in terms of an mmap. This should be just an implementation detail, but unfortunately for 32-bit versions of Python this creates a limit of 4GB on the files that can be used. The work around is either to get a 64-bit Python, or just stick with version 2.0.
- The
ConstBitArrayandConstBitStreamclasses no longer copy byte data when a slice or a read takes place, they just take a reference. This is mostly a very nice optimisation, but there are occasions where it could have an adverse effect. For example if a very large bitstring is created, a small slice taken and the original deleted. The byte data from the large bitstring would still be retained in memory. - Optimisations. Once again this version should be faster than the last. The module is still pure Python but some of the reorganisation was to make it more feasible to put some of the code into Cython or similar, so hopefully more speed will be on the way.
- Bug fix: Using peek and read for a single bit now returns a new bitstring as was intended, rather than the old behaviour of returning a bool.
- Removed HTML docs from source archive - better to use the online version.
This is a major release, with a number of backwardly incompatible changes. The main change is the removal of many methods, all of which have simple alternatives. Other changes are quite minor but may need some recoding.
There are a few new features, most of which have been made to help the stream-lining of the API. As always there are performance improvements and some API changes were made purely with future performance in mind.
About half of the class methods have been removed from the API. They all have simple alternatives, so what remains is more powerful and easier to remember. The removed methods are listed here on the left, with their equivalent replacements on the right:
s.advancebit() -> s.pos += 1
s.advancebits(bits) -> s.pos += bits
s.advancebyte() -> s.pos += 8
s.advancebytes(bytes) -> s.pos += 8*bytes
s.allunset([a, b]) -> s.all(False, [a, b])
s.anyunset([a, b]) -> s.any(False, [a, b])
s.delete(bits, pos) -> del s[pos:pos+bits]
s.peekbit() -> s.peek(1)
s.peekbitlist(a, b) -> s.peeklist([a, b])
s.peekbits(bits) -> s.peek(bits)
s.peekbyte() -> s.peek(8)
s.peekbytelist(a, b) -> s.peeklist([8*a, 8*b])
s.peekbytes(bytes) -> s.peek(8*bytes)
s.readbit() -> s.read(1)
s.readbitlist(a, b) -> s.readlist([a, b])
s.readbits(bits) -> s.read(bits)
s.readbyte() -> s.read(8)
s.readbytelist(a, b) -> s.readlist([8*a, 8*b])
s.readbytes(bytes) -> s.read(8*bytes)
s.retreatbit() -> s.pos -= 1
s.retreatbits(bits) -> s.pos -= bits
s.retreatbyte() -> s.pos -= 8
s.retreatbytes(bytes) -> s.pos -= 8*bytes
s.reversebytes(start, end) -> s.byteswap(0, start, end)
s.seek(pos) -> s.pos = pos
s.seekbyte(bytepos) -> s.bytepos = bytepos
s.slice(start, end, step) -> s[start:end:step]
s.tell() -> s.pos
s.tellbyte() -> s.bytepos
s.truncateend(bits) -> del s[-bits:]
s.truncatestart(bits) -> del s[:bits]
s.unset([a, b]) -> s.set(False, [a, b])
Many of these methods have been deprecated for the last few releases, but there are some new removals too. Any recoding needed should be quite straightforward, so while I apologise for the hassle, I had to take the opportunity to streamline and rationalise what was becoming a bit of an overblown API.
The set/unset methods have been combined in a single method, which now takes a boolean as its first argument:
s.set([a, b]) -> s.set(1, [a, b])
s.unset([a, b]) -> s.set(0, [a, b])
s.allset([a, b]) -> s.all(1, [a, b])
s.allunset([a, b]) -> s.all(0, [a, b])
s.anyset([a, b]) -> s.any(1, [a, b])
s.anyunset([a, b]) -> s.any(0, [a, b])
The all and any methods (previously called allset, allunset, anyset and
anyunset) no longer accept a single bit position. The recommended way of
testing a single bit is just to index it, for example instead of:
>>> if s.all(True, i):just use
>>> if s[i]:If you really want to you can of course use an iterable with a single
element, such as s.any(False, [i]), but it's clearer just to write
not s[i].
If a read or peek goes beyond the end of the bitstring then a ReadError
will be raised. The previous behaviour was that the rest of the bitstring
would be returned and no exception raised.
The base class for errors in the bitstring module is now just Error, so
it will likely appear in your code as bitstring.Error instead of
the rather repetitive bitstring.BitStringError.
A single index slice (such as s[5]) will now return a bool (i.e. True or
False) rather than a single bit bitstring. This is partly to reflect the
style of the bytearray type, which returns an integer for single items, but
mostly to avoid common errors like:
>>> if s[0]:
... do_something()While the intent of this code snippet is quite clear (i.e. do_something if
the first bit of s is set) under the old rules s[0] would be true as long
as s wasn't empty. That's because any one-bit bitstring was true as it was a
non-empty container. Under the new rule s[0] is True if s starts with a 1
bit and False if s starts with a 0 bit.
The change does not affect reads and peeks, so s.peek(1) will still return
a single bit bitstring, which leads on to the next item...
Previously a bitstring was False if it had no elements, otherwise it was True.
This is standard behaviour for containers, but wasn't very useful for a container
of just 0s and 1s. The new behaviour means that the bitstring is False if it
has no 1 bits. This means that code like this:
>>> if s.peek(1):
... do_something()should work as you'd expect. It also means that Bits(1000), Bits(0x00) and
Bits('uint:12=0') are all also False. If you need to check for the emptiness of
a bitstring then instead check the len property:
if s -> if s.len
if not s -> if not s.len
Previously you could create bitstring using expressions like:
>>> s = Bits(hex='0xabcde', offset=4, length=13)This has now been disallowed, and the offset and length parameters may only be used when initialising with bytes or a file. To replace the old behaviour you could instead use
>>> s = Bits(hex='0xabcde')[4:17]Methods with a format parameter have had it renamed to fmt, to prevent
hiding the built-in format. Affects methods unpack, read, peek, readlist,
peeklist and byteswap and the pack function.
This means that for the affected methods (unpack, readlist and peeklist) you
will need to use an iterable to specify multiple items. This is easier to
show than to describe, so instead of
>>> a, b, c, d = s.readlist('uint:12', 'hex:4', 'bin:7')you would instead write
>>> a, b, c, d = s.readlist(['uint:12', 'hex:4', 'bin:7'])Note that you could still use the single string 'uint:12, hex:4, bin:7' if
you preferred.
You can no longer use True and False to initialise single bit bitstrings.
The reasoning behind this is that as bool is a subclass of int, it really is
bad practice to have Bits(False) be different to Bits(0) and to have Bits(True)
different to Bits(1).
If you have used bool auto-initialisation then you will have to be careful to
replace it as the bools will now be interpreted as ints, so Bits(False) will
be empty (a bitstring of length 0), and Bits(True) will be a single zero bit
(a bitstring of length 1). Sorry for the confusion, but I think this will
prevent bigger problems in the future.
There are a few alternatives for creating a single bit bitstring. My favourite it to use a list with a single item:
Bits(False) -> Bits([0])
Bits(True) -> Bits([1])
Previously if you created a bitstring from a file, either by auto-initialising with a file object or using the filename parameter, the file would not be read into memory unless you tried to modify it, at which point the whole file would be read.
The new behaviour depends on whether you create a Bits or a BitString from the
file. If you create a Bits (which is immutable) then the file will never be
read into memory. This allows very large files to be opened for examination
even if they could never fit in memory.
If however you create a BitString, the whole of the referenced file will be read
to store in memory. If the file is very big this could take a long time, or fail,
but the idea is that in saying you want the mutable BitString you are implicitly
saying that you want to make changes and so (for now) we need to load it into
memory.
The new strategy is a bit more predictable in terms of performance than the old.
The main point to remember is that if you want to open a file and don't plan to
alter the bitstring then use the Bits class rather than BitString.
Just to be clear, in neither case will the contents of the file ever be changed -
if you want to output the modified BitString then use the tofile method, for
example.
If a find is unsuccessful then an empty tuple is returned (which is False in a
boolean sense) otherwise a single item tuple with the bit position is returned
(which is True in a boolean sense). You shouldn't need to recode unless you
explicitly compared the result of a find to True or False, for example this
snippet doesn't need to be altered:
>>> if s.find('0x23'):
... print(s.bitpos) but you could now instead use
>>> found = s.find('0x23')
>>> if found:
... print(found[0])The reason for returning the bit position in a tuple is so that finding at
position zero can still be True - it's the tuple (0,) - whereas not found can
be False - the empty tuple ().
This method just counts the number of 1 or 0 bits in the bitstring.
>>> s = Bits('0x31fff4')
>>> s.count(1)
16The read, readlist, peek and peeklist methods now accept integers as parameters
to mean "read this many bits and return a bitstring". This has allowed a number
of methods to be removed from this release, so for example instead of:
>>> a, b, c = s.readbits(5, 6, 7)
>>> if s.peekbit():
... do_something()you should write:
>>> a, b, c = s.readlist([5, 6, 7])
>>> if s.peek(1):
... do_something()
The byteswap method now allows a format specifier of 0 (the default) to signify
that all of the whole bytes should be reversed. This means that calling just
byteswap() is almost equivalent to the now removed bytereverse() method (a small
difference is that byteswap won't raise an exception if the bitstring isn't a
whole number of bytes long).
So rather than writing:
>>> a = Bits(bytes=some_bytearray)
you can just write
>>> a = Bits(some_bytearray)This also works for the bytes type, but only if you're using Python 3.
For Python 2 it's not possible to distinguish between a bytes object and a
str. For this reason this method should be used with some caution as it will
make you code behave differently with the different major Python versions.
>>> b = Bits(b'abcd\x23\x00') # Only Python 3!This means that you can for example write:
>>> a = BitString(100) # 100 zero bits
>>> a.set(1) # set all bits to 1
>>> a.all(1) # are all bits set to 1?
True
>>> a.any(0) # are any set to 0?
False
>>> a.invert() # invert every bitAs well as renaming BitStringError to just Error
there are also new exceptions which use Error as a base class.
These can be caught in preference to Error if you need finer control.
The new exceptions sometimes also derive from built-in exceptions:
ByteAlignError(Error) # whole byte position or length needed.
ReadError(Error, IndexError) # reading or peeking off the end of the bitstring.
CreationError(Error, ValueError) # inappropriate argument during bitstring creation.
InterpretError(Error, ValueError) # inappropriate interpretation of binary data.
Changes the endianness in-place according to a format string or integer(s) giving the byte pattern. See the manual for details.
>>> s = BitString('0x00112233445566')
>>> s.byteswap(2)
3
>>> s
BitString('0x11003322554466')
>>> s.byteswap('h')
3
>>> s
BitString('0x00112233445566')
>>> s.byteswap([2, 5])
1
>>> s
BitString('0x11006655443322')For example:
>>> s = Bits('100*0x123')For example:
>>> s = Bits('3*(uint:6=3, 0b1)')The start and end parameters of many methods may now be negative, with the
same meaning as for negative slice indices. Affects all methods with these
parameters.
The Bits class now derives from collections.Sequence, while the BitString
class derives from collections.MutableSequence.
Keywords for token lengths are now permitted when reading. So for example, you can write
>>> s = bitstring.pack('4*(uint:n)', 2, 3, 4, 5, n=7)
>>> s.unpack('4*(uint:n)', n=7)
[2, 3, 4, 5]Also its parameter has changed from bitstringlist to sequence. This is
technically a backward incompatibility in the unlikely event that you are
referring to the parameter by name.
Rather than a long list of initialisers the __init__ methods now use a
**kwargs dictionary for all initialisers except auto. This should have no
effect, except that this is a small backward incompatibility if you use
positional arguments when initialising with anything other than auto
(which would be rather unusual).
Introducing a brand new class, Bits, representing an immutable sequence of
bits.
The Bits class is the base class for the mutable BitString. The differences
between Bits and BitStrings are:
-
Bitsare immutable, so once they have been created their value cannot change. This of course means that mutating methods (append,replace,deletc.) are not available forBits. -
Bitsare hashable, so they can be used in sets and as keys in dictionaries. -
Bitsare potentially more efficient thanBitStrings, both in terms of computation and memory. The current implementation is only marginally more efficient though - this should improve in future versions.
You can switch from Bits to a BitString or vice versa by constructing a new
object from the old.
>>> s = Bits('0xabcd')
>>> t = BitString(s)
>>> t.append('0xe')
>>> u = Bits(t)The relationship between Bits and BitString is supposed to loosely mirror that
between bytes and bytearray in Python 3.
A number of methods have been flagged for removal in version 2. Deprecation warnings will now be given, which include an alternative way to do the same thing. All of the deprecated methods have simpler equivalent alternatives.
>>> t = s.slice(0, 2)
__main__:1: DeprecationWarning: Call to deprecated function slice.
Instead of 's.slice(a, b, c)' use 's[a:b:c]'.The deprecated methods are: advancebit, advancebits, advancebyte, advancebytes,
retreatbit, retreatbits, retreatbyte, retreatbytes, tell, seek, slice, delete,
tellbyte, seekbyte, truncatestart and truncateend.
Booleans have been added to the list of types that can 'auto' initialise a bitstring.
>>> zerobit = BitString(False)
>>> onebit = BitString(True)More methods have been sped up, in particular some deletions and insertions.
A rare problem with truncating the start of bitstrings was fixed.
A possible problem outputting the final byte in tofile() was fixed.
This version hopefully fixes an installation problem for platforms with case-sensitive file systems. There are no new features or other bug fixes.
This is a minor update with (almost) no new features.
- Improved efficiency.
The speed of many typical operations has been increased, some substantially.
- Initialise from integer.
A BitString of '0' bits can be created using just an integer to give the length in bits. So instead of
>>> s = BitString(length=100)you can write just
>>> s = BitString(100)This matches the behaviour of bytearrays and (in Python 3) bytes.
- A defect related to using the
set/unsetfunctions on BitStrings initialised from a file has been fixed.
Note that this version will not work for Python 2.4 or 2.5. There may be an update for these Python versions some time next year, but it's not a priority quite yet. Also note that only one version is now provided, which works for Python 2.6 and 3.x (done with the minimum of hackery!)
A fair number of functions have improved efficiency, some quite dramatically.
Although these functions don't do anything that couldn't be done before, they do make some common use cases much more efficient. If you need to set or check single bits then these are the functions you need.
set / unset : Set bit(s) to 1 or 0 respectively.
allset / allunset : Check if all bits are 1 or all 0.
anyset / anyunset : Check if any bits are 1 or any 0.
For example
>>> s = BitString(length=1000)
>>> s.set((10, 100, 44, 12, 1))
>>> s.allunset((2, 22, 222))
True
>>> s.anyset(range(7, 77))
Trueror / rol : Rotate bits to the right or left respectively.
>>> s = BitString('0b100000000')
>>> s.ror(2)
>>> s.bin
'0b001000000'
>>> s.rol(5)
>>> s.bin
'0b000000100'New float initialisations and interpretations are available. These only work for BitStrings of length 32 or 64 bits.
>>> s = BitString(float=0.2, length=64)
>>> s.float
0.200000000000000001
>>> t = bitstring.pack('<3f', -0.4, 1e34, 17.0)
>>> t.hex
'0xcdccccbedf84f67700008841'This token returns a bytes object (equivalent to a str in Python 2.6).
>>> s = BitString('0x010203')
>>> s.unpack('bytes:2, bytes:1')
['\x01\x02', '\x03']So for example these are equivalent:
a, b = s.readlist('uint:12, uint:12')
a, b = s.readlist('12, 12')This is a straight port of version 1.0.0 to Python 3.
For changes since the last Python 3 release read all the way down in this document to version 0.4.3.
This version will also work for Python 2.6, but there's no advantage to using it over the 1.0.0 release. It won't work for anything before 2.6.
Version 1 is here!
This is the first release not to carry the 'beta' tag. It contains a couple of minor new features but is principally a release to fix the API. If you've been using an older version then you almost certainly will have to recode a bit. If you're not ready to do that then you may wish to delay updating.
So the bad news is that there are lots of small changes to the API. The good news is that all the changes are pretty trivial, the new API is cleaner and more 'Pythonic', and that by making it version 1.0 I'm promising not to tweak it again for some time.
The functions read, readbits, readbytes, peek, peekbits and peekbytes now only
ever return a single item, never a list.
The new functions readlist, readbitlist, readbytelist, peeklist, peekbitlist
and peekbytelist can be used to read multiple items and will always return a
list.
So a line like:
>>> a, b = s.read('uint:12, hex:32')becomes
>>> a, b = s.readlist('uint:12, hex:32')Functions have been renamed as follows:
seekbit -> seek
tellbit -> tell
reversebits -> reverse
deletebits -> delete
tostring -> tobytes
and a couple have been removed altogether:
deletebytes - use delete instead.
empty - use 'not s' rather than 's.empty()'.
The parameters startbit and endbit have been renamed start and end.
This affects the functions slice, find, findall, rfind, reverse, cut and split.
The parameter bitpos has been renamed to pos. The affects the functions
seek, tell, insert, overwrite and delete.
This means that you can't chain functions together so
>>> s.append('0x00').prepend('0xff')
>>> t = s.reverse()Needs to be rewritten
>>> s.append('0x00')
>>> s.prepend('0xff')
>>> s.reverse()
>>> t = sAffects truncatestart, truncateend, insert, overwrite, delete, append,
prepend, reverse and reversebytes.
The data property has been renamed to bytes. Also, if the BitString is not a
whole number of bytes then a ValueError exception will be raised when using
bytes as a 'getter'.
Properties len and pos have been added to replace length and bitpos,
although the longer names have not been removed, so you can continue to use them
if you prefer.
The unpack function now always returns a list, never a single item.
BitStrings are now 'unhashable', so calling hash on one or making a set will fail.
The colon separating the token name from its length is now mandatory. So for
example BitString('uint12=100') becomes BitString('uint:12=100').
Removed support for the 'bytes' token in format strings. Instead of
s.read('bytes:4') use s.read('bits:32').
These do much as you'd expect; they return True or False depending on whether
the BitString starts or ends with the parameter.
>>> BitString('0xef342').startswith('0b11101')
TrueFinally some tools for dealing with endianness!
- New interpretations are now available for whole-byte BitStrings that treat them as big, little, or native-endian.
>>> big = BitString(intbe=1, length=16) # or BitString('intbe:16=1') if you prefer.
>>> little = BitString(intle=1, length=16)
>>> print big.hex, little.hex
0x0001 0x0100
>>> print big.intbe, little.intle
1 1- 'Struct'-like compact format codes
To save some typing when using pack, unpack, read and peek, compact format codes based on those used in the struct and array modules have been added. These must start with a character indicating the endianness (>, < or @ for big, little and native-endian), followed by characters giving the format:
b 1-byte signed int
B 1-byte unsigned int
h 2-byte signed int
H 2-byte unsigned int
l 4-byte signed int
L 4-byte unsigned int
q 8-byte signed int
Q 8-byte unsigned int
For example:
>>> s = bitstring.pack('<4h', 0, 1, 2, 3)creates a BitString with four little-endian 2-byte integers. While
>>> x, y, z = s.read('>hhl')reads them back as two big-endian two-byte integers and one four-byte big endian integer.
Of course you can combine this new format with the old ones however you like:
>>> s.unpack('<h, intle:24, uint:5, bin')
[0, 131073, 0, '0b0000000001100000000']This update introduces pack and unpack functions for creating and dissembling BitStrings.
- New pack() and unpack() functions.
The module level pack function provides a flexible new method for creating BitStrings. Tokens for BitString 'literals' can be used in the same way as in the constructor.
>>> from bitstring import BitString, pack
>>> a = pack('0b11, 0xff, 0o77, int:5=-1, se=33')You can also leave placeholders in the format, which will be filled in by the values provided.
>>> b = pack('uint:10, hex:4', 33, 'f')Finally, you can use a dictionary or keywords.
>>> c = pack('bin=a, hex=b, bin=a', a='010', b='ef')The unpack function is similar to the read function except that it always unpacks from the start of the BitString.
>>> x, y = b.unpack('uint:10, hex')If a token is given without a length (as above) then it will expand to fill the remaining bits in the BitString. This also now works with read() and peek().
- New
tostring()andtofile()functions.
The tostring() function just returns the data as a string, with up to seven
zero bits appended to byte align. The tofile() function does the same except
writes to a file object.
>>> f = open('myfile', 'wb')
>>> BitString('0x1234ff').tofile(f)- Other changes.
The use of '=' is now mandatory in 'auto' initialisers. Tokens like 'uint12 100' will
no longer work. Also, the use of a ':' before the length is encouraged, but not yet
mandated. So the previous example should be written as 'uint:12=100'.
The 'auto' initialiser will now take a file object.
>>> f = open('myfile', 'rb')
>>> s = BitString(f)This update breaks backward compatibility in a couple of areas. The only one
you probably need to be concerned about is the change to the default for
bytealigned in find, replace, split, etc.
See the user manual for more details on each of these items.
- Expanded abilities of 'auto' initialiser.
More types can be initialised through the 'auto' initialiser. For example instead of
>>> a = BitString(uint=44, length=16)you can write
>>> a = BitString('uint16=44')Also, different comma-separated tokens will be joined together, e.g.
>>> b = BitString('0xff') + 'int8=-5'can be written
>>> b = BitString('0xff, int8=-5')- New formatted
read()andpeek()functions.
These takes a format string similar to that used in the auto initialiser. If only one token is provided then a single value is returned, otherwise a list of values is returned.
>>> start_code, width, height = s.read('hex32, uint12, uint12')is equivalent to
>>> start_code = s.readbits(32).hex
>>> width = s.readbits(12).uint
>>> height = s.readbits(12).uintThe tokens are:
int n : n bits as an unsigned integer.
uint n : n bits as a signed integer.
hex n : n bits as a hexadecimal string.
oct n : n bits as an octal string.
bin n : n bits as a binary string.
ue : next bits as an unsigned exp-Golomb.
se : next bits as a signed exp-Golomb.
bits n : n bits as a new BitString.
bytes n : n bytes as a new BitString.
See the user manual for more details.
hex()andoct()functions removed.
The special functions for hex() and oct() have been removed. Please use the
hex and oct properties instead.
>>> hex(s)becomes
>>> s.hex- join made a member function.
The join function must now be called on a BitString object, which will be
used to join the list together. You may need to recode slightly:
>>> s = bitstring.join('0x34', '0b1001', '0b1')becomes
>>> s = BitString().join('0x34', '0b1001', '0b1')- More than one value allowed in
readbits,readbytes,peekbitsandpeekbytes
If you specify more than one bit or byte length then a list of BitStrings will be returned.
>>> a, b, c = s.readbits(10, 5, 5)is equivalent to
>>> a = readbits(10)
>>> b = readbits(5)
>>> c = readbits(5)bytealigneddefaults to False, and is at the end of the parameter list
Functions that have a bytealigned parameter have changed so that it now
defaults to False rather than True. Also, its position in the parameter list
has changed to be at the end. You may need to recode slightly (sorry!)
readueandreadsefunctions have been removed
Instead you should use the new read function with a 'ue' or 'se' token:
>>> i = s.readue()becomes
>>> i = s.read('ue')This is more flexible as you can read multiple items in one go, plus you can
now also use the peek function with ue and se.
- Minor bugs fixed.
See the issue tracker for more details.
This is a minor update. This release is the first to bundle the bitstring manual. This is a PDF and you can find it in the docs directory.
Changes in version 0.4.3
- New 'cut' function
This function returns a generator for constant sized chunks of a BitString.
>>> for byte in s.cut(8):
... do_something_with(byte)You can also specify a startbit and endbit, as well as a count, which limits
the number of items generated:
>>> first100TSPackets = list(s.cut(188*8, count=100))slicefunction now equivalent to__getitem__.
This means that a step can also be given to the slice function so that the
following are now the same thing, and it's just a personal preference which
to use:
>>> s1 = s[a:b:c]
>>> s2 = s.slice(a, b, c)- findall gets a 'count' parameter.
So now
>>> list(a.findall(s, count=n))is equivalent to
>>> list(a.findall(s))[:n]except that it won't need to generate the whole list and so is much more efficient.
- Changes to 'split'.
The split function now has a 'count' parameter rather than 'maxsplit'. This
makes the interface closer to that for cut, replace and findall. The final item
generated is now no longer the whole of the rest of the BitString.
- A couple of minor bugs were fixed. See the issue tracker for details.
This is a minor update, and almost doesn't break compatibility with version
0.4.0, but with the slight exception of findall() returning a generator,
detailed below.
Changes in version 0.4.2
- Stepping in slices
The use of the step parameter (also known as the stride) in slices has been added. Its use is a little non-standard as it effectively gives a multiplicative factor to apply to the start and stop parameters, rather than skipping over bits.
For example this makes it much more convenient if you want to give slices in
terms of bytes instead of bits. Instead of writing s[a*8:b*8] you can use
s[a:b:8].
When using a step the BitString is effectively truncated to a multiple of the
step, so s[::8] is equal to s if s is an integer number of bytes, otherwise it
is truncated by up to 7 bits. So the final seven complete 16-bit words could be
written as s[-7::16]
Negative slices are also allowed, and should do what you'd expect. So for
example s[::-1] returns a bit-reversed copy of s (which is similar to
s.reversebits(), which does the same operation on s in-place). As another
example, to get the first 10 bytes in reverse byte order you could use
s_bytereversed = s[0:10:-8].
- Removed restrictions on offset
You can now specify an offset of greater than 7 bits when creating a BitString,
and the use of offset is also now permitted when using the filename initialiser.
This is useful when you want to create a BitString from the middle of a file
without having to read the file into memory.
>>> f = BitString(filename='reallybigfile', offset=8000000, length=32)- Integers can be assigned to slices
You can now assign an integer to a slice of a BitString. If the integer doesn't
fit in the size of slice given then a ValueError exception is raised. So this
is now allowed and works as expected:
>>> s[8:16] = 106and is equivalent to
>>> s[8:16] = BitString(uint=106, length=8)- Fewer exceptions raised
Some changes have been made to slicing so that fewer exceptions are raised,
bringing the interface closer to that for lists. So for example trying to delete
past the end of the BitString will now just delete to the end, rather than
raising a ValueError.
- Initialisation from lists and tuples
A new option for the auto initialiser is to pass it a list or tuple. The items
in the list or tuple are evaluated as booleans and the bits in the BitString are
set to 1 for True items and 0 for False items. This can be used anywhere the
auto initialiser can currently be used. For example:
>>> a = BitString([True, 7, False, 0, ()]) # 0b11000
>>> b = a + ['Yes', ''] # Adds '0b10'
>>> (True, True, False) in a
True-
reversebits()now has optionalstartbitandendbitparameters. -
As an optimisation
findall()will return a generator, rather than a list. If you still want the whole list then of course you can just calllist()on the generator. -
Improved efficiency of rfind().
-
A couple of minor bugs were fixed. See the issue tracker for details.
This version is just a port of version 0.4.0 to Python 3. All the unit tests pass, but beyond that only limited ad hoc testing has been done and so it should be considered an experimental release. That said, the unit test coverage is very good - I'm just not sure if anyone even wants a Python 3 version!
Changes in version 0.4.0
- New functions
Added rfind(), findall(), replace(). These do pretty much what you'd expect -
see the docstrings or the wiki for more information.
- More special functions
Some missing functions were added: __repr__, __contains__, __rand__,
__ror__, __rxor__ and __delitem__.
- Miscellany
A couple of small bugs were fixed (see the issue tracker).
There are some small backward incompatibilities relative to version 0.3.2:
- Combined
findandfindbytealigned
findbytealigned has been removed, and becomes part of find. The default
start position has changed on both find and split to be the start of the
BitString. You may need to recode:
>>> s1.find(bs)
>>> s2.findbytealigned(bs)
>>> s2.split(bs)becomes
>>> s1.find(bs, bytealigned=False, startbit=s1.bitpos)
>>> s2.find(bs, startbit=s1.bitpos) # bytealigned defaults to True
>>> s2.split(bs, startbit=s2.bitpos)- Reading off end of BitString no longer raises exception.
Previously a read or peek function that encountered the end of the BitString
would raise a ValueError. It will now instead return the remainder of the
BitString, which could be an empty BitString. This is closer to the file
object interface.
- Removed visibility of offset.
The offset property was previously read-only, and has now been removed from
public view altogether. As it is used internally for efficiency reasons you
shouldn't really have needed to use it. If you do then use the _offset parameter
instead (with caution).
Changes in version 0.3.2
- Better performance
A number of functions (especially find and findbytealigned) have been sped
up considerably.
- Bit-wise operations
Added support for bit-wise AND (&), OR (|) and XOR (^). For example:
>>> a = BitString('0b00111')
>>> print a & '0b10101'
0b00101- Miscellany
Added seekbit and seekbyte functions. These complement the advance and
retreat functions, although you can still just use bitpos and bytepos
properties directly.
>>> a.seekbit(100) # Equivalent to a.bitpos = 100Allowed comparisons between BitString objects and strings. For example this
will now work:
>>> a = BitString('0b00001111')
>>> a == '0x0f'
TrueChanges in version 0.3.1
This version only adds features and fixes bugs relative to 0.3.0, and doesn't break backwards compatibility.
- Octal interpretation and initialisation
The oct property now joins bin and hex. Just prefix octal numbers with '0o'.
>>> a = BitString('0o755')
>>> print a.bin
0b111101101- Simpler copying
Rather than using b = copy.copy(a) to create a copy of a BitString, now you
can just use b = BitString(a).
- More special methods
Lots of new special methods added, for example bit-shifting via << and >>,
equality testing via == and !=, bit inversion (~) and concatenation using *.
Also __setitem__ is now supported so BitString objects can be modified using
standard index notation.
- Proper installer
Finally got round to writing the distutils script. To install just
python setup.py install.
Changes in version 0.3.0
- Simpler initialisation from binary and hexadecimal
The first argument in the BitString constructor is now called auto and will
attempt to interpret the type of a string. Prefix binary numbers with '0b'
and hexadecimals with '0x'.
>>> a = BitString('0b0') # single zero bit
>>> b = BitString('0xffff') # two bytesPreviously the first argument was data, so if you relied on this then you will need to recode:
>>> a = BitString('\x00\x00\x01\xb3') # Don't do this any more!becomes
>>> a = BitString(data='\x00\x00\x01\xb3')or just
>>> a = BitString('0x000001b3')This new notation can also be used in functions that take a BitString as an
argument. For example:
>>> a = BitString('0x0011') + '0xff'
>>> a.insert('0b001', 6)
>>> a.find('0b1111')- BitString made more mutable
The functions append, deletebits, insert, overwrite, truncatestart and
truncateend now modify the BitString that they act upon. This allows for
cleaner and more efficient code, but you may need to rewrite slightly if you
depended upon the old behaviour:
>>> a = BitString(hex='0xffff')
>>> a = a.append(BitString(hex='0x00'))
>>> b = a.deletebits(10, 10)becomes:
>>> a = BitString('0xffff')
>>> a.append('0x00')
>>> b = copy.copy(a)
>>> b.deletebits(10, 10)Thanks to Frank Aune for suggestions in this and other areas.
- Changes to printing
The binary interpretation of a BitString is now prepended with '0b'. This is
in keeping with the Python 2.6 (and 3.0) bin function. The prefix is optional
when initialising using bin=.
Also, if you just print a BitString with no interpretation it will pick
something appropriate - hex if it is an integer number of bytes, otherwise
binary. If the BitString representation is very long it will be truncated
by '...' so it is only an approximate interpretation.
>>> a = BitString('0b0011111')
>>> print a
0b0011111
>>> a += '0b0'
>>> print a
0x3e- More convenience functions
Some missing functions such as advancebit and deletebytes have been added. Also
a number of peek functions make an appearance as have prepend and reversebits.
See the Tutorial for more details.
Some fairly minor updates, not really deserving of a whole version point update.
First release! 🎉