You can use Unicorn for non-commercial use [1], but yes, for commercial use you need to buy a license.

> It's much faster to use precomputed tables per algorithm

You're absolutely right about using precomputed tables per algorithm. That is the secret to the library's speed.

> Free and small is my safeclib, which does about half of it.

I like safeclib! It's nice to hear from the author. It's worth distinguishing that safeclib is a safer string library whereas Unicorn is a Unicode algorithms library, not a string library.

[1] https://github.com/railgunlabs/unicorn/blob/master/LICENSE

Is it me or does this feel a bit weird? It seems like you're using the comments section here to self-advertise for exposure.

I read it like — "businesses can't use this without paying the OP, however, if you're a business you can get 50% of the way there by using _my_ library, and you don't even have to pay me!". It comes off incredibly rude to try to undercut the OP like this.

MISRA C states the following rationale:

“A single point of exit is required by IEC 61508 and ISO 26262 as part of the requirements for a modular approach.

Early returns may lead to the unintentional omission of function termination code.

If a function has exit points interspersed with statements that produce persistent side effects, it is not easy to determine which side effects will occur when the function is executed.”

Note that the MISRA C rule is merely advisory, meaning it is a recommendation and not a hard requirement (i.e. it’s a “should” and not a “shall”).

It's a bit like an operating system write-protecting pages. Sometimes you write-protect pages that the process really shouldn't write to, like shared libraries or something like that. But sometimes you write-protect pages that you actually expect a program to write to, like memory-mapped pages, because then when the write happens it triggers something else (like copy-on-write or marking a page dirty or something).

Rules like "Don't use dynamically allocated memory" are one example of this -- not that they really expect you never to do it, but that marking it "Required" is a way to force you to document how you plan to make it safe.

Similarly, if it's easier to rearrange a function to have only a single exit point than to explain why you need multiple exit points, just rearrange it; you really need multiple exit points, just document why.

  profile_begin("func");
  a = temp_arena_begin();
  // ... code
  temp_arena_end();
  profile_end();

I would not be in the least surprised if someone has a compiler/transpiler from a higher level language to some C code which checks all MISRA boxes.

Otherwise this leads to duplication of cleanup code similar to

  allocate_something()
  ..
  if failed(foo) {
    deallocate_something()
    return FAILED;
  }
  ..
  deallocate_something()
  return SUCCESS;

    #  You may not reverse engineer, decompile, disassemble, or otherwise attempt
    #  to derive the source code or underlying structure of this script

[1] https://github.com/railgunlabs/unicorn/releases/

ICU is a large library, typically around ~40 MB depending on the platform, whereas Unicorn, with all features enabled, is only about 600 KB.

ICU has a broader scope: it's not just a Unicode library, but also an internationalization library. Unicorn, on the other hand, is specifically focused on Unicode algorithms.

ICU wasn't designed to be customized. It's also non-MISRA compliant and written in C++11. In contrast, Unicorn is written in C99, fully customizable, MISRA compliant, and only requires a few features from libc [1]. It's far more portable.

[1] https://github.com/railgunlabs/unicorn/?tab=readme-ov-file#u...