llvm/compiler-rt/test/builtins/Unit/endianness.h

#ifndef ENDIANNESS_H
#define ENDIANNESS_H

/*
 * Known limitations:
 *   Middle endian systems are not handled currently.
 */

#if defined(__SVR4) && defined(__sun)
#include <sys/byteorder.h>

#if _BYTE_ORDER == _BIG_ENDIAN
#define _YUGA_LITTLE_ENDIAN 0
#define _YUGA_BIG_ENDIAN    1
#elif _BYTE_ORDER == _LITTLE_ENDIAN 
#define _YUGA_LITTLE_ENDIAN 1
#define _YUGA_BIG_ENDIAN    0
#endif /* _BYTE_ORDER */

#endif /* Solaris */

/* .. */

#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonflyBSD__) || defined(__minix)
#include <sys/endian.h>

#if _BYTE_ORDER == _BIG_ENDIAN
#define _YUGA_LITTLE_ENDIAN 0
#define _YUGA_BIG_ENDIAN    1
#elif _BYTE_ORDER == _LITTLE_ENDIAN
#define _YUGA_LITTLE_ENDIAN 1
#define _YUGA_BIG_ENDIAN    0
#endif /* _BYTE_ORDER */

#endif /* *BSD */

/* .. */

#if defined(__OpenBSD__)
#include <machine/endian.h>

#if _BYTE_ORDER == _BIG_ENDIAN
#define _YUGA_LITTLE_ENDIAN 0
#define _YUGA_BIG_ENDIAN    1
#elif _BYTE_ORDER == _LITTLE_ENDIAN
#define _YUGA_LITTLE_ENDIAN 1
#define _YUGA_BIG_ENDIAN    0
#endif /* _BYTE_ORDER */

#endif /* OpenBSD */

/* .. */

/* Mac OSX has __BIG_ENDIAN__ or __LITTLE_ENDIAN__ automatically set by the compiler (at least with GCC) */
#if defined(__APPLE__) && defined(__MACH__) || defined(__ellcc__ )

#ifdef __BIG_ENDIAN__
#if __BIG_ENDIAN__
#define _YUGA_LITTLE_ENDIAN 0
#define _YUGA_BIG_ENDIAN    1
#endif
#endif /* __BIG_ENDIAN__ */

#ifdef __LITTLE_ENDIAN__
#if __LITTLE_ENDIAN__
#define _YUGA_LITTLE_ENDIAN 1
#define _YUGA_BIG_ENDIAN    0
#endif
#endif /* __LITTLE_ENDIAN__ */

#endif /* Mac OSX */

/* .. */

#if defined(__linux__)
#include <endian.h>

#if __BYTE_ORDER == __BIG_ENDIAN
#define _YUGA_LITTLE_ENDIAN 0
#define _YUGA_BIG_ENDIAN    1
#elif __BYTE_ORDER == __LITTLE_ENDIAN
#define _YUGA_LITTLE_ENDIAN 1
#define _YUGA_BIG_ENDIAN    0
#endif /* __BYTE_ORDER */

#endif /* GNU/Linux */

/* . */

#if !defined(_YUGA_LITTLE_ENDIAN) || !defined(_YUGA_BIG_ENDIAN)
#error Unable to determine endian
#endif /* Check we found an endianness correctly. */

#endif /* ENDIANNESS_H */