Re: [9fans] ntohl, htonl, &c

[adr <adr@SDF.ORG>]

On Fri, 13 May 2022, ori@eigenstate.org wrote:

> Date: Fri, 13 May 2022 10:22:13 -0400
> From: ori@eigenstate.org
> Reply-To: 9fans <9fans@9fans.net>
> To: 9fans@9fans.net
> Subject: Re: [9fans] ntohl, htonl, &c
> 
> Quoth Alex Musolino <alex@musolino.id.au>:
>>> I'm getting rid of ape but I need the functions at
>>> /sys/src/ape/lib/bsd/ntohl.c to port some software.  These functions
>>> just change endianness.  Is there some native similar functions
>>> somebody is aware of?  lookman is not helping me here.  I don't want
>>> to add code if a similar functionality is already in the system.
>>
>> No. Those functions are mental.  The Plan 9 way is so simple that
>> there's no library, everyone just brings their own macros/functions.
>> The trick is: if you care about the order of bytes then you should be
>> dealing with a byte array, not a native integral type.
>
> see also:
>
> https://commandcenter.blogspot.com/2012/04/byte-order-fallacy.html

Oh, I agree with that and I think this was a key in the design of
9p. I wasn't asking for the existence of those functions elsewhere,
but for some common code to change endianness of some data structure,
stream, etc. Not because is hard to do, just to not repeat the same
code again and again. Every format of image, audio, etc store
data in a determinded endianness, so I imagined that some functions
or macros could be defined already somewhere.

Regards,
adr.

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