[Gllug] endian.h

[Tethys]

rich at annexia.org writes:

>> >So betoh32 <-> ntohl && letoh32 <-> htonl
>
> [...]
>
>Hmmm ... except that it probably won't fail. On, say, Sparc machines,
>the betoh32 (Big Endian to Host) transformation _is_ a null transformation,
>because Sparcs are already Big Endian.

Yes, it will still fail. In fact, if you do a direct swap as described,
it'll even fail on little endian, too!

On little endian:

	betoh32 -> ntohl -> transform    (correct)
	letoh32 -> htonl -> transform    (*WRONG*)

On big endian:

	betoh32 -> ntohl -> no transform (correct)
	letoh32 -> htonl -> no transform (*WRONG*)

On little endian, you can fix that with "#define letoh32(x) (x)".
The same trick doesn't work on big endian, though, and you need
to resort to a manual conversion. With glibc, you can use bswap_32(),
but it's not portable.

Tet

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