Fixing ill-formed UTF-16 strings with SIMD instructions

Fixing ill-formed UTF-16 strings with SIMD instructions | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 13 September 2025 V1 Latest version Share on Fixing ill-formed UTF-16 strings with SIMD instructions Authors : Robert Clausecker and Daniel Lemire [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.175778474.46841590/v1 264 views 161 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract UTF-16 is a widely used Unicode encoding representing characters with one or two 16-bit code units. The format relies on surrogate pairs to encode characters beyond the Basic Multilingual Plane, requiring a high surrogate followed by a low surrogate. Ill-formed UTF-16 strings—where surrogates are mismatched—can arise from data corruption or improper encoding, posing security and reliability risks. Consequently, programming languages such as JavaScript include functions to fix ill-formed UTF-16 strings by replacing mismatched surrogates with the Unicode replacement character (U+FFFD). We propose using Single Instruction, Multiple Data (SIMD) instructions to handle multiple code units in parallel, enabling faster and more efficient execution. Our software is part of the Google JavaScript engine (V8) and thus part of several major Web browsers. Supplementary Material File (fixutf16.pdf) Download 333.18 KB Information & Authors Information Version history V1 Version 1 13 September 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords simd text processing unicode utf-16 vectorization Authors Affiliations Robert Clausecker Zuse-Institut Berlin View all articles by this author Daniel Lemire [email protected] Universite TELUQ View all articles by this author Metrics & Citations Metrics Article Usage 264 views 161 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Robert Clausecker, Daniel Lemire. Fixing ill-formed UTF-16 strings with SIMD instructions. Authorea . 13 September 2025. DOI: https://doi.org/10.22541/au.175778474.46841590/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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