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https://github.com/kenn/bitwise
Bitwise: Fast, memory efficient bitwise operations on large binary strings
https://github.com/kenn/bitwise
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Bitwise: Fast, memory efficient bitwise operations on large binary strings
- Host: GitHub
- URL: https://github.com/kenn/bitwise
- Owner: kenn
- License: mit
- Created: 2011-12-13T04:40:56.000Z (over 12 years ago)
- Default Branch: master
- Last Pushed: 2022-12-27T01:03:55.000Z (over 1 year ago)
- Last Synced: 2024-01-31T01:01:57.516Z (4 months ago)
- Language: Ruby
- Homepage: http://rubygems.org/gems/bitwise
- Size: 34.2 KB
- Stars: 43
- Watchers: 2
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Lists
- awesome-ruby - Bitwise - Fast, memory efficient bitwise operations on large binary strings (Core Extensions)
README
Bitwise
=======
Fast, memory efficient bitwise operations on large binary strings.
Internally a bit array is represented as a ruby string with `Encoding::BINARY` encoding, which keeps billions of bits in a workable footprint.
* 1,000,000 bits = 125KB
* 10,000,000 bits = 1.25MB
* 100,000,000 bits = 12.5MB
* 1,000,000,000 bits = 125MB
If you need a bit storage for ActiveRecord instead, take a look at [ActiveFlag](https://github.com/kenn/active_flag).
Install
-------
gem install bitwise
Usage
-----
Set and unset bits:
```ruby
b = Bitwise.new("\x00")
b.bits
=> "00000000"
b.set_at(1)
b.set_at(4)
b.bits
=> "01001000"
b.unset_at(1)
b.bits
=> "00001000"
b.set_at?(4)
=> true
b.unset_at?(4)
=> false
```
String-based accessor:
```ruby
b = Bitwise.new
b.raw = "abc"
b.size
=> 3
b.bits
=> "011000010110001001100011"
b.raw.unpack('C*')
=> [97, 98, 99]
```
Index-based accessor:
```ruby
b = Bitwise.new
b.indexes = [1, 2, 4, 8, 16]
b.bits
=> "011010001000000010000000"
b.indexes
=> [1, 2, 4, 8, 16]
b.cardinality
=> 5
b.set_at(10)
b.bits
=> "011010001010000010000000"
b.indexes
=> [1, 2, 4, 8, 10, 16]
b.cardinality
=> 6
```
Bit-based accessor is also provided for convenience, but be aware that it's not efficient. Use string-based accessor whenever possible.
```ruby
b = Bitwise.new
b.bits = '0100100010'
b.bits
=> "0100100010000000"
```
NOT, OR, AND and XOR:
```ruby
b1 = Bitwise.new
b2 = Bitwise.new
b1.indexes = [1, 2, 3, 5, 6]
b2.indexes = [1, 2, 4, 8, 16]
(~b1).indexes
=> [0, 4, 7]
(b1 | b2).indexes
=> [1, 2, 3, 4, 5, 6, 8, 16]
(b1 & b2).indexes
=> [1, 2]
(b1 ^ b2).indexes
=> [3, 4, 5, 6, 8, 16]
```
As a bonus, `Bitwise.string_not`, `Bitwise.string_union`, `Bitwise.string_intersect`, and `Bitwise.string_xor` can be used as a standalone utility to work with any binary string.
```ruby
Bitwise.string_not "\xF0"
=> "\x0F"
Bitwise.string_union "\xF0","\xFF"
=> "\xFF"
Bitwise.string_intersect "\xF0","\xFF"
=> "\xF0"
Bitwise.string_xor "\xF0","\xFF"
=> "\x0F"
```