bitarray / bitvector / bitspan

This repo provides an alternative to C++'s std::bitset with all the features of C++20's <bit> header.

As with std::bitset, bitarray supports arbitrary length arrays of bits. It also supports dynamic bit lengths bitvector (on std::vector). It supports mmap'd bitsets bitspan (via std::span).

It aims to be simpler, faster, and more featureful.

Faster, because:

• most operations are in-place, to eliminate large copies
• the word size can be larger to reduce the number of iterations. potentially doing half as many iterations, std::bitset uses long
• or the word size can be smaller to reduce wasted space (relevant for many small bitsets)

The added features are (or will be):

• [ ] Easy casts between bitarray, bitvector, bitspan
• [ ] Easy constructors from std::array, std::vector, std::span, std::initializer_list
• [x] Directly access all the underlying words
  • bitset only allows you to get the lowest unsigned long long's worth of bits
  • or output to a string of '1's and '0's...
• [x] Easily change the underlying word type for whatever performance/storage needs (8/16/32/64/128 bit types are all supported and tested)
• [x] Supports all C++20 <bit> bitwise operations
  • popcount, rotl, rotr, count_{l,r}_{zero,one}
• [x] deposit/extract and interleave/deinterleave, supported by pdep/pext

Dependencies

• C++20
• Target CPU with support for the BMI2 instruction set (for pdep/pext support, which gather/scatter and interleave/deinterleave rely on)

For testing and installing:

• Meson sudo apt install meson

Usage

Include bitarray.hh and use bitarray::bitarray<N> instead of std::bitset<N>, or bitarray::bitvector(N), or bitarray::bitspan(span)

Testing

test.sh