endianness (was Re: sysadmin qualifications (Re: apt-get vs. aptitude))

[Jonathan Dowland <jmtd@debian.org>]

On Thu, Oct 17, 2013 at 05:29:33PM +0200, berenger.morel@neutralite.org wrote:
> Speaking about endianness, it really is hard to manage:
> 
> void myfunction( ... )
> {
> #ifdef BIG_ENDIAN
> move_bytes_in_a_specific_order
> #else
> move_bytes_in_the_other_specific_order
> #endif
> }

Bad way to manage endian in C. Better to have branching based on C
itself (rather than preprocessor), otherwise you run the risk of never
testing code outside the branch your dev machine(s) match. E.g. use

char is_little_endian( … ) {
  int i = 1;
  int *p = &i;
  return 1 == *(char*)p;
}

Or similar. The test will likely be compiled out as a no-op anyway with
decent compilers (GCC: yes; Sun Workshop: no.)