Transcoding Billions of Unicode Characters per Second with SIMD Instructions

TL;DR

This paper introduces SIMD-optimized algorithms for Unicode text transcoding, significantly increasing speed and making large-scale text format conversions more efficient on modern processors.

Contribution

It presents novel SIMD-based transcoding algorithms that outperform existing methods, with open-source implementation for reproducibility.

Findings

Transcoding speed increased by an order of magnitude

Algorithms work efficiently on x64 and ARM architectures

Open source library available for practical use

Abstract

In software, text is often represented using Unicode formats (UTF-8 and UTF-16). We frequently have to convert text from one format to the other, a process called transcoding. Popular transcoding functions are slower than state-of-the-art disks and networks. These transcoding functions make little use of the single-instruction-multiple-data (SIMD) instructions available on commodity processors. By designing transcoding algorithms for SIMD instructions, we multiply the speed of transcoding on current systems (x64 and ARM). To ensure reproducibility, we make our software freely available as an open source library.