# BigBit
[](https://crates.io/crates/bitbit "BigBit on Crates.io")
[](https://docs.rs/bigbit "BigBit on Docs.rs")
This is an implementation of the [BigBit standard][BigBitStd], used for representing arbitrarily large numbers and strings in a compact way. The only implementation provided by the author is [a Node.js implementation](https://github.com/bigbit/bigbitjs "BigBit.js on GitHub") — this crate aims to implement the functionality presented there with idiomatic Rust code.
In short, the specification describes 3 formats:
- **Head Byte** (***HB***), used for storing extremely large (but still finitely large) signed integers *and* decimal fractions without losing precision
- **Extended Head Byte** (***EHB***), used for storing arbitrarily large signed integers *and* decimal fractions without losing precision as long as sufficent storage space is provided.
- **Linked Bytes** (***LB***), used for storing arbitrarily large **unsigned integers**, mainly used directly inside the Extended Head Byte format to store the exponent and the number of additional coefficient bytes, but also useful for storing strings better than both UTF-8 and UTF-16.
Since this is a format parser, `#![no_std]` is enabled by default, meaning that `alloc` is the only dependency, allowing you to use this in a freestanding environment.
## State
Currently, not the entire BigBit standard is implemented, and **the crate is not ready for use in production just yet**. There are also **no stability guarantees whatsoever**. Here's a list of what's already done:
- Head Byte number storage (not really finished, just a stub)
- Linked Bytes number storage and arithmetic
- Converting Linked Bytes to and from primitive integers
- Displaying Linked Bytes numbers in binary, octal, decimal and hexadecimal using formatters as well as other bases (arbitrary from 2 to 36) using a dedicated method
- Borrowed Linked Bytes (required for EHB) — a Linked Bytes number which doesn't own its contents and is a slice into an EHB number (still a stub)
And here's a list of what's not finished just yet:
- Creating \[E\]HB numbers from primitive integers and `f32`/`f64` (most likely will be added in 0.1.0)
- The Extended Header Byte format (will be added in 0.0.x)
- Arithmetic operations (addition, subtraction, multiplication and division are all defined by the BigBit standard) for \[E\]HB; the main issue is dealing with the exponents (will mark the 1.0.0 release, might be partially added over the course of 0.x.x releases)
- Strings encoded using Linked Bytes (will be added in 0.0.x)
- `Debug` and `Display` formatting for \[E\]HB (i.e. converting the numbers either into a debugging-friendly representation as an array of bytes or a string representing the number in decimal scientific notation or full notation, as well as other numeric notations; simple `Debug` and `Display` decimal formatting will be added in 0.1.0 while the rest is planned for 1.0.0)
- **Tests** (planned for 0.1.0 but might be partially added earlier)
## Changelog
### 0.0.5
- Implemented arithmetic with `self` as the right operand for Linked Bytes, removing the need to always explicitly write `op1 + &op2` (same for other operators)
- Fixed the Crates.io badge to link to `bigbit` instead of `bi`**`t`**`bit`
- Added `usize` to the list of primitive integer types for which Linked Bytes arithmetic is implemented
- Added the `DivRem` and `DivRemAssign` traits for combined division (one operation to get the quotient and remainder)
- Renamed `HeadByte::from_headbyte_and_followup` into `from_raw_parts` ***(breaking)***
- Implemented logarithm with arbitrary base for Linked Bytes
- Implemented string formatting for Linked Bytes
### 0.0.4
- Implemented Linked Bytes multiplication and division
- Implemented Linked Bytes arithmetic with primitive integers
- Reorganized the internal module structure
- Added `LBNumRef`
- Implemented some more traits on `LBNum`
### 0.0.3
- Implemented Linked Bytes subtraction
- Started the reorganization
- Fixed addition bugs
If you're wondering why all versions until `0.0.3` are yanked, these had a minor LB addition bug, so please upgrade if you haven't already.
[BigBitStd]: https://github.com/amitguptagwl/BigBit "BitBit specification on GitHub"