UInt12Arrays.jl

Synposis

UInt12Arrays.jl is a Julia package to support the use of arrays of 12-bit unsigned integers and their elements. This package's main purpose is to provide a UInt12Array type that allows for the indexing into arrays of packed UInt12s.

Background

Dealing with 12-bit integers is challenging because the the underlying LLVM integer support is based on integers that are a multiple of a byte (8-bits). For integer types that are a multiple of a byte, see BitIntegers.jl.

To use unsigned 12-bit integers (UInt12) in computations, it is easiest to load them as unsigned 16-bit integers (UInt16). However, to conserve memory it may be advantageous to keep the 12-bit integers packed into a dense array.

What this package does

1. Provide a UInt12Array that allows for indexing of arrays of packed UInt12s.
2. Allow access of 12-bit integers as type UInt16 (default element type of UInt12Array)
3. Provides a prototype UInt12 type that boxes a UInt16 and implement 12-bit arithmetic
4. Provides lookup table (LUT) and single instruction multiple data (SIMD) methods for unpacking 12-bit data

Why is the default element type a UInt16 rather than UInt12?

As mentioned in the background, there is better hardware and compiler support for UInt16. Additionally the supporting code for UInt12 is under development with the main implementation being a boxed UInt16.