twibint

Rust crate for arbitrarily big integers, signed or unsigned.

This crate does not need any dependency, and relies only on the standard library. Some dependencies are optional, depending on a specific feature (see list of features below).

The main API of this crate is to export 2 types: BigUint and BigInt, meant to represent unsigned or signed integers of arbitrarily large absolute value. They are meant to be used in almost any way a regular integer can be used, though they don't implement the Copy trait.

Build, documentation, benchmarks and tests are available the usual way calling the following:

cargo build
cargo docs
cargo test

For benchmarks, please visit the benches folder.

Performance

More details and scripts about performance are available in the benches folder.

TL;DR -> The current state of twibints performance (v0.2.7) is: Addition, Subtraction and Multiplication are faster than for Python integers, and faster then num-bigint at some scales. Division remains extremely slow.

List of features

• rand: exports the function gen_random_biguint: enables the possibility to generate a random integer with a specific number of bits. Uses rand crate as a dependency.
• pyo3: Only used to generate python bindings, it's only meant to be used indirectly via the pip install . command. Uses pyo3 crate as a dependency.
• unsafe: Enables accelerations that use unsafe Rust. Enabled by default. Disabled via the flag --no-default-features for pure safe Rust (compile time enforced).

Install as a Python package

Simply use from the base directory

python3 -m pip install .

This crate seems faster than the default Python integers for addition and multiplication above a certain numbers of bits (between 1000 and 10000 bits).

Python tests are available to be run in the pytest framework. They are located in the tests folder and should provide ample example usage. Run the tests with

pytest tests

Performance comparison with Python's default integers are available in the benches folder.

Changelog for version 0.2

This new version contains extensive accelerations for addition, subtraction, and multiplication on x86_64 machines. I used no modern extensions of x86, so these acceleration should be portable accross this family of machines. These will probably also have performance repercussions on many other features.

These acceleration are mostly due to dropping inline assembly for core loops, and are based on unsafe Rust. Other unsafe features used include smartly swapping between &[u32] and &[u64] slices via pointers (when alignment is lucky).

To disable any unsafe code, use with the flag --no-default-features for a slower experience, but fully compiled in safe Rust.