Simple Useful Libraries: The C++17 header-only dynamic bitset

Overview

dynamic_bitset

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Simple Useful Libraries: The C++17 header-only dynamic bitset

Requirements

To use this dynamic bitset, you will need a C++17 compliant compiler. If you use CMake and want to use the dynamic bitset as a subproject, you will need CMake 3.10 or later.

Usage sample

#include <sul/dynamic_bitset.hpp>
#include <iostream>
#include <random>

int main()
{
	// predefined bitset
	sul::dynamic_bitset<> bitset1(12, 0b0100010110111);
	std::cout << "bitset1     = " << bitset1 << std::endl;

	// random bitset
	std::minstd_rand rand(std::random_device{}());
	std::bernoulli_distribution dist;
	sul::dynamic_bitset<> bitset2;
	for(size_t i = 0; i < 12; ++i)
	{
		bitset2.push_back(dist(rand));
	}
	std::cout << "bitset2     = " << bitset2 << std::endl;

	std::cout << "common bits = " << (bitset1 & bitset2) << std::endl;
	return 0;
}

Possible output:

bitset1     = 100010110111
bitset2     = 001011011011
common bits = 000010010011

Test it on godbolt.org.

Optional dependency

Optionally, libpopcnt will be used optimize the bits counting operations, if the header is available (__has_include(<libpopcnt.h>)) and DYNAMIC_BITSET_NO_LIBPOPCNT is not defined.

Integration

As it is a header-only library, the easiest way to integrate the sul::dynamic_bitset class in your project is to just copy the sul folder in your project sources. Optionally, if you also copy libpopcnt.h from libpopcnt, it will be used by default if it is available.

CMake integration

If you use CMake and want to use the dynamic bitset as a subproject, clone the repository (or add it as a git submodule) in a sub-folder of your project. Then, in your CMakeLists.txt add:

add_subdirectory(<path_to_dynamic_bitset_folder>)

It will define the dynamic_bitset target and the alias target sul::dynamic_bitset that you can use to add the folder containing dynamic_bitset.hpp to your project header folders. To do so, in your CMakeLists.txt add:

target_link_libraries(<your_project_target> PRIVATE sul::dynamic_bitset)

For example, a simple project with the repository as a git submodule in the extlibs folder, could have a CMakeLists.txt similar to this:

cmake_minimum_required(VERSION 3.10)
project(CoolProject LANGUAGES CXX)

add_executable(CoolProject main.cpp)

add_subdirectory(extlibs/dynamic_bitset)
target_link_libraries(CoolProject PRIVATE sul::dynamic_bitset)

If you pulled the git submodule libpopcnt (in extlibs) and set the dynamic bitset CMake options DYNAMICBITSET_USE_LIBPOPCNT and DYNAMICBITSET_USE_LIBPOPCNT_SUBMODULE to ON(default values), the folder containing libpopcnt.h will also be added to the headers paths and libpopcnt will be used.

CMake options

Descriptions

  • DYNAMICBITSET_NO_NAMESPACE: Put the dynamic_bitset class in the global namespace instead of the sul namespace (not recommended)
  • DYNAMICBITSET_USE_LIBPOPCNT: Enable using libpopcnt for bits counting operations
  • DYNAMICBITSET_USE_LIBPOPCNT_SUBMODULE: Enable adding libpopcnt submodule to include paths (disable if your project already include libpopcnt)
  • DYNAMICBITSET_BUILD_EXAMPLE: Enable building example for dynamic_bitset
  • DYNAMICBITSET_BUILD_TESTS: Enable building tests for dynamic_bitset
  • DYNAMICBITSET_BUILD_DOCS: Enable building documentation for dynamic_bitset
  • DYNAMICBITSET_FORMAT_TARGET: Enable generating a code formating target for dynamic_bitset
  • DYNAMICBITSET_HEADERS_TARGET_IDE: Enable generating a target with headers for ide for dynamic_bitset

Default values

Option Default value as master project Default value as subdirectory
DYNAMICBITSET_NO_NAMESPACE OFF OFF
DYNAMICBITSET_USE_LIBPOPCNT ON ON
DYNAMICBITSET_USE_LIBPOPCNT_SUBMODULE ON ON
DYNAMICBITSET_BUILD_EXAMPLE ON OFF
DYNAMICBITSET_BUILD_TESTS ON OFF
DYNAMICBITSET_BUILD_DOCS ON OFF
DYNAMICBITSET_FORMAT_TARGET ON OFF
DYNAMICBITSET_HEADERS_TARGET_IDE ON OFF

Build tests, example, and documentation

The latest version of the documentation is available online here.

To build the tests, the example, and the documentation, git submodules are required, so don't forget to pull the submodules with the repository using --recursive:

$ git clone --recursive https://github.com/pinam45/dynamic_bitset.git

or if you have already cloned the repository:

$ git submodule update --init --recursive

The project uses CMake to build and define the options DYNAMICBITSET_BUILD_TESTS, DYNAMICBITSET_BUILD_EXAMPLE, and DYNAMICBITSET_BUILD_DOCS to enable the generation of the tests, example, and documentation targets, these option are enabled by default if the project is the master project (not included from another CMakeLists.txt with add_subdirectory).

Generating the documentation requires Doxygen 1.8.16 or later and is done by building the target dynamic_bitset_docs. For running the tests, build the dynamic_bitset_tests target and launch the tests using ctest.

See Running CMake and the ctest documentation for more information. On linux, a common way of doing this is:

$ mkdir cmake-build
$ cd cmake-build
$ cmake ..
$ cmake --build .
$ ctest

On Windows, there is batch files available to configure a Visual Studio project in the ide folder.

License

dynamic_bitset is licensed under the MIT License:

Copyright © 2019 Maxime Pinard

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Issues
  • Binary (assignment) operations should not require the same `size()`

    Binary (assignment) operations should not require the same `size()`

    Binary (assignment) operations require the same size() of their operands (example). While this makes the implementation easy it enforces additional boilerplate code if the user wants to use differently-sized sets.

    The implementation will still be easy as the resulting bit set will either have the smaller or the larger of both size()s:

    In case of assignment operators I would expect the LHS operand to expand its size() to fit the RHS if required. Of course, the loops must only iterate to the minimum of both sizes.

    In case of binary operators it should be sufficient to swap LHS and RHS in order to avoid additional reallocations.

    opened by a-ludi 5
  • Atomic operations

    Atomic operations

    Hi, I want to use this library in an openmp program. Since different threads can set bits in a same block, I wonder how I can set a bit atomically without using a mutex?

    opened by asesidaa 4
  • push_back_block

    push_back_block

    To simplify serialization with json I use on my side a push_back_block:

    constexpr void dynamic_bitset<Block, Allocator>::push_back_block(Block blockValue)
    {
    	m_blocks.push_back(blockValue);
    }
    

    Binary serialization used .data(); for json 'for each block' save an uint32 or uint64 based on internal blocktype

    opened by soufianekhiat 3
  • gdb segmentation fault

    gdb segmentation fault

    When debugging code that uses dynamic_bitset with gdb I get a segmentation fault when I try to print a bitset.

    (gdb) print bitset[0]
    $1 = {m_block = @0xd, m_mask = 93825020145982}
    (gdb) print bitset
    $2 = {Segmentation fault 
    

    Also, how should I read the output of the first print?

    opened by anassmeskini 2
  • Add an own namespace

    Add an own namespace

    Could you probably add an own namespace? Otherwise it may be a bit difficult to use in larger projects.

    enhancement 
    opened by IceflowRE 2
  • Missing .data() for binary serialization

    Missing .data() for binary serialization

    Very cool,

    I'm using it on my side with minor modification:

    constexpr std::byte* data()
    {
    	return reinterpret_cast<std::byte*>(&m_blocks[0]);
    }
    constexpr std::byte const* data() const
    {
    	return reinterpret_cast<std::byte const*>(&m_blocks[0]);
    }
    

    Which is on my side convenient for binary serialization.

    enhancement 
    opened by soufianekhiat 2
  • performance?

    performance?

    The following is a comparison of different bitset implementations: https://cs.up.ac.za/cs/vpieterse/pub/PieterseEtAl_SAICSIT2010.pdf. It would be interesting to see a similar comparison with this library.

    WIP 
    opened by mlund 6
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