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Utility subroutines for working with bitfields

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use Util::Bitfield;

my $number = 0b0001011101101010;

# source integer, number of bits, starting position, word size
say extract-bits($number,3,3,16); # 5
say sprintf "%016b",insert-bits(7, $number, 3, 3, 16); # "0001111101101010"


"Bitfields" are common in hardware interfaces and compact binary data formats, allowing the packing of multiple fields of information within a single machine word sized value for instance, hardware examples might include device registers or gpio ports, software examples include MP3 "frame headers".

Whilst highly efficient for data storage and transmission, they're usually a pain to work with in high level languages, requiring masking and shifting of numbers possibly multiple times to get a value you can sensibly use in your program.

Also because it's not something I at least tend to do very frequently the patterns don't come naturally and I end up starting from first principles every time.

So to this end, on being presented with some data that required unpacking of a bit field, I made this fairly simple library to extract and insert an arbitrary number of bits from an arbitrary location within a larger integer as smaller integers.


Assuming you have a working Rakudo installation you should be able to install this with zef :

# From the source directory

zef install .

# Remote installation

zef install Util::Bitfield

Other install mechanisms may be become available in the future.


Suggestions/patches are welcomed via github at



This is free software.

Please see the LICENCE file in the distribution

© Jonathan Stowe 2016 - 2021