38 lines
2 KiB
Text
38 lines
2 KiB
Text
= Bits
|
|
|
|
Bits provides methods on a bit array type.
|
|
|
|
The Bits type holds a fixed size array of bits, numbered consecutively
|
|
from zero. Some set-like operations are possible, but the API is more
|
|
array-like or register-like.
|
|
|
|
image:https://godoc.org/github.com/soniakeys/bits?status.svg[link=https://godoc.org/github.com/soniakeys/bits] image:https://travis-ci.org/soniakeys/bits.svg[link=https://travis-ci.org/soniakeys/bits]
|
|
|
|
== Motivation and history
|
|
|
|
This package evolved from needs of my library of
|
|
https://github.com/soniakeys/graph[graph algorithms]. For graph algorithms
|
|
a common need is to store a single bit of information per node in a way that
|
|
is both fast and memory efficient. I began by using `big.Int` from the standard
|
|
library, then wrapped big.Int in a type. From time to time I considered
|
|
other publicly available bit array or bit set packages, such as Will
|
|
Fitzgerald's popular https://github.com/willf/bitset[bitset], but there were
|
|
always little reasons I preferred my own type and methods. My type that
|
|
wrapped `big.Int` met my needs until some simple benchmarks indicated it
|
|
might be causing performance problems. Some further experiments supported
|
|
this hypothesis so I ran further tests with a prototype bit array written
|
|
from scratch. Then satisfied that my custom bit array was solving the graph
|
|
performance problems, I decided to move it to a separate package with the
|
|
idea it might have more general utility. For the initial version of this
|
|
package I did the following:
|
|
|
|
- implemented a few tests to demonstrate fundamental correctness
|
|
- brought over most methods of my type that wrapped big.Int
|
|
- changed the index type from the graph-specific node index to a general `int`
|
|
- replaced some custom bit-twiddling with use of the new `math/bits` package
|
|
in the standard library
|
|
- renamed a few methods for clarity
|
|
- added a few methods for symmetry
|
|
- added a few new methods I had seen a need for in my graph library
|
|
- added doc, examples, tests, and more tests for 100% coverage
|
|
- added this readme
|