[Zlib-devel] crc32 big/little endian

[Joakim Tjernlund]

>
> On Apr 21, 2010, at 6:49 AM, Joakim Tjernlund wrote:
> > Surely it should be enough to detect endian at compile
> > time and only compile the one needed for that particular CPU?
>
> It can't be detected at compile time when cross-compiling, and some processors

Sure you can, use #ifdef __BYTE_ORDER == __BIG_ENDIAN like any
other app does.

> (e.g. PowerPC) can change their endianess while running!  The cost of keeping

In what OS would ppc do that? Never seen one and I haven't seen any app endian
dependent app support such things.

> both sets of code and tables is very small, and detecting endianess at run

I don't think 16KB+ as small overhead, it is a lot.

> time is highly reliable and takes negligible time.  If an application really

Yes, but so is
#ifndef __BYTE_ORDER
#error byte_order not defined!
#elif __BYTE_ORDER == __BIG_ENDIAN
#warning BIG endian
#elif __BYTE_ORDER == __LITTLE_ENDIAN
#warning LITTLE endian
#endif

> cares about that level of memory usage, they can modify the code and keep only
> the part they need.  Or they can define NOBYFOUR and make the code even
> smaller with a 1K table and no endian-dependant code.

It would be better if there are any freak OS out there that can change endian on
the fly define NOBYFOUR instead of making all the rest suffer.

>
> Mark