Unicorn is a lightweight, embeddable implementation of essential Unicode® algorithms written in C99.
Unicorn is compliant with the MISRA C:2012 coding standard. It's perfect for resource constrained devices like microcontrollers and IoT devices.
- Normalization (docs)
- Case mapping (docs)
- Collation (docs)
- Segmentation (docs)
- Short string compression (docs)
- UTF-8, 16, and 32 iterators and convertors (docs)
- Various character properties (docs)
- MISRA C:2012 compliance (learn more)
- Distributed as a single header/source amalgamation
- Written in C99 with no external dependencies
Unicorn is fully customizable. You can choose which Unicode algorithms and character properties to include. You can even exclude character blocks for scripts your application does not support.
To customize Unicorn, modify features.json and run the generate.pyz script.
This script will generate the unicorn.c and unicorn.h source files which you can compile with your C project.
When Unicorn is built with a provided build system (e.g. CMake), the script is executed automatically as part of the build process.
The schema for features.json is documented here.
Unicorn is ultra portable. It does not require an FPU or 64-bit integers. It's written in C99 and only requires a few features from libc which are listed in the following table.
| Header | Types | Macros | Functions |
|---|---|---|---|
| stdint.h | int8_t, int16_t, int32_t uint8_t, uint16_t, uint32_t |
||
| string.h | memcpy, memset, memcmp |
||
| stddef.h | size_t |
NULL |
|
| stdbool.h | bool, true, false |
||
| assert.h | assert |
Unicorn honors all Mandatory, most Required, and most Advisory rules defined by MIRSA C:2012. Deviations are documented here. You are encouraged to audit Unicorn and verify its level of conformance is acceptable.
All functions that operate on text can accept UTF-8, UTF-16, UTF-32, or Unicode scalar values. UTF-16 and UTF-32 are accepted as big endian, little endian, and native byte order.
By default, the implementation performs runtime safety checks to guard against malformed or maliciously encoded text. If you know your text isn't malformed you can opt-in to skip these checks to improve processing performance.
Unicorn is thread-safe except for the following caveats:
- Functions that allocate memory are only as thread-safe as the allocator itself.
- The configuration API is not thread-safe, however, in typical usage it's only invoked at application startup and only if the default configuration is unsatisfactory.
All operations in Unicorn are atomic. That means either an operation occurs or nothing occurs at all. This guarantees errors, such as out-of-memory errors, never corrupt internal state. This also means if an error occurs, like an out of memory error, then you can recover (free up memory) and try the same operation again.
- Official Unicode conformance tests
- Manually written tests
- Out-of-memory tests
- Fuzz tests
- Static analysis
- Valgrind analysis
- Code sanitizers (UBSAN, ASAN, and MSAN)
- Extensive use of assert() and run-time checks
Unit tests are executed on both little and big endian hardware as part of continuous integration.
Download a prebuilt header/source amalgamation from the releases page or generate one yourself by running ./generate.pyz (requires Python 3.9 or newer).
The prebuilt amalgamation includes all features whereas the one you generate yourself only includes the features you specify in features.json.
Alternatively, build a linkable library with
$ ./configure
$ make
$ make install
or CMake.
Submit patches and bug reports to RailgunLabs.com/contribute. Do not open a pull request. The pull request tab is enabled because GitHub does not provide a mechanism to disable it.
Unicorn is free of charge for non-commercial use. You can purchase a commercial license from Railgun Labs.
The unamalgamated C source code, the programs for generating the Unicode data, and the unit tests are not open source. Access to them is granted exclusively to commercial licensees.
Unicode® is a registered trademark of Unicode, Inc. in the United States and other countries. This project is not in any way associated with or endorsed or sponsored by Unicode, Inc. (aka The Unicode Consortium).