Re: [PATCH 3/3] define _bswap_constant_16/32 for musl This uses the implementation from libiio (https://github.com/analogdevicesinc/libiio/commit/9c6c6a432a0cbe2832bc97a7eeddfb61f6b8b856) Also restored the old behavior from the old util.h.

[Stefano Brivio <sbrivio@redhat.com>]

On Fri,  3 Mar 2023 22:49:31 +0000
KuhnChris <kuhnchris+github@kuhnchris.eu> wrote:

> ---
>  util.h | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)

Here, what you wrote in the subject (first line of commit message)
should be in the commit message itself. Example of commit message for
this:

--
util: Provide own __bswap_constant_{16,32} if not defined by C library

musl, and possibly other C libraries, don't define __bswap_constant_16
and __bswap_constant_32. Define them if they aren't.

Signed-off-by: Name Surname <email address>
--

The first line becomes the patch subject. Here, there would be no
strict need to mention libiio because that's just one example of the
same trivial implementation copied over and over again in many
projects, which might come from pretty much anywhere.

Wwas it copied from glibc? Was it written by the author of that
commit? I don't think it qualifies as copyrightable work:

  https://en.wikipedia.org/wiki/Threshold_of_originality

...but you can also do that, as you have the link at hand, if you
actually took it from there.

> diff --git a/util.h b/util.h
> index 7315ce2..a6ad4ad 100644
> --- a/util.h
> +++ b/util.h
> @@ -91,7 +91,16 @@
>  #define MAC_ZERO		((uint8_t [ETH_ALEN]){ 0 })
>  #define MAC_IS_ZERO(addr)	(!memcmp((addr), MAC_ZERO, ETH_ALEN))
>  
> -#if defined(__GLIBC__) || defined(__UCLIBC__)
> +#ifndef __bswap_constant_16
> +#define __bswap_constant_16(x) \
> +	((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
> +#endif
> +
> +#ifndef __bswap_constant_32
> +#define __bswap_constant_32(x) \
> +	((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
> +	 (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
> +#endif
>  
>  #if __BYTE_ORDER == __BIG_ENDIAN
>  #define	htons_constant(x)	(x)
> @@ -101,14 +110,6 @@
>  #define	htonl_constant(x)	(__bswap_constant_32(x))
>  #endif
>  
> -#else 
> -
> -/* mainly musl fallback */
> -
> -#define	htons_constant(x)	(x)
> -#define	htonl_constant(x)	(x)
> -
> -#endif

And this, again, shouldn't be in the first patch.

>  
>  #define IN4_IS_ADDR_UNSPECIFIED(a) \
>  	((a)->s_addr == htonl(INADDR_ANY))

I understand this might be a lot to digest and a bit of effort, so let
me know -- you figured out most of the issues and did all the tests, I
can also fix up the patches for you.

-- 
Stefano