Thanks Brian and David, Sounds like #include <endian.h> and testing for either __LITTLE_ENDIAN or __BIG_ENDIAN is the way to go. The code I was studying tested for "__BIG_ENDIAN__" with no relevant #includes... Although this string might exist it seems a little flaky to me. Lee. -----Original Message----- From: David Daney [mailto:ddaney@xxxxxxxxxx] Sent: Wednesday, July 25, 2007 4:27 PM To: gcc-help@xxxxxxxxxxx Cc: Lee Rhodes Subject: Re: Where to find documentation on pre-defined macros Brian Dessent wrote: > Lee Rhodes wrote: > >> Nonetheless, if I had to write low-level code that depended on >> ENDIANess, what is the most robust/platform-independent way to make >> that determination (and not pay run-time execution costs)? > > Autoconf has the AC_C_BIGENDIAN macro that will determine the > endian-ness of the target at configure time. And #include <endian.h> defines __BYTE_ORDER, __LITTLE_ENDIAN, and __BIG_ENDIAN which can be tested at compile time. You can also use htons/ntohs and ntonl/ntohl and they take care of it for you. David Daney
