I'd say that it depends. But 98% of the strings you'll find in UEFI (including APIs) are UCS-2 CHAR16 strings.

On Tue, Jun 7, 2022 at 9:19 AM Ayush Singh <ayushdevel1325@gmail.com> wrote:
Thanks, Pedro,

However, according to the specs, it is possible to construct ASCII
Strings as well. So when would ASCII Strings be used over normal UCS-2
Strings?

Ayush Singh

On Tue, Jun 7, 2022 at 1:13 PM Pedro Falcato <pedro.falcato@gmail.com> wrote:
>
> Hi Ayush,
>
> In the latest UEFI 2.9 spec, it's specified under 2.3.1 that CHAR8 strings/characters are (usually) ASCII, and CHAR16 strings/characters are (usually) UCS-2 (*not* UTF-16).
>
> On Tue, Jun 7, 2022 at 7:02 AM Ayush Singh <ayushdevel1325@gmail.com> wrote:
>>
>> Hello everyone, I am trying to write an implementation for UEFI
>> strings in Rust and just wanted clarification about some things.
>>
>> Are UEFI Strings UTF-16 encoded? I have looked at some previous Rust
>> implementations for this and it seems UEFI does not support the whole
>> UTF-16 but rather only UCS-2
>> (https://en.wikipedia.org/wiki/Universal_Coded_Character_Set) which is
>> a subset of UTF-16.
>>
>> There is also something called WTF-8
>> (https://en.wikipedia.org/wiki/UTF-8#WTF-8) which Rust uses to
>> represent OsStrings in Windows which is supposed to use UTF-16 (?).
>>
>> Anyway, if someone can point me to the resources/specifications of
>> UEFI Strings, it would be a great help.
>>
>> Ayush Singh
>>
>>
>>
>>
>>
>
>
> --
> Pedro Falcato


--
Pedro Falcato