Re: [PATCH v2 2/6] bswap.h: Add support for __BYTE_ORDER__

From: Collin Funk <collin.funk1@gmail.com>
Date: Jun 12, 2025, 00:43 UTC
Message-ID: <87wm9hkcvr.fsf@gmail.com>
In-Reply-To: <aEoeUCcXYByjU5HR@fruit.crustytoothpaste.net>

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

Show 9 quoted lines

> One additional option you can add if you want (it's completely optional)
> is that if `__STDC_VERSION__` is 202311L or larger, then you can
> `#include <stdbit.h>`, which has `__STDC_ENDIAN_LITTLE__`,
> `__STDC_ENDIAN_BIG__`, and `__STDC_ENDIAN_NATIVE__`.
>
> That will work on a modern GCC or clang with an appropriate compiler
> flag.  I don't know about MSVC, but it might be an option for people who
> want to use more esoteric compilers which support standards but aren't
> very compatible with GCC and clang.

Another standard that is too new to be common, but POSIX.1-2024 added <endian.h> with BYTE_ORDER, LITTLE_ENDIAN, and BIG_ENDIAN [1].

In practice, some systems will have it because glibc had it for a long time.

Collin

[1] https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/endian.h.html