Hi!
So, assuming I'm on glibc with GCC 4.5 on powerpc64-linux.
On Tue, Mar 24, 2020 at 09:49:42AM +0100, Martin Liška wrote:
> +/* Detect endianess based on __BYTE_ORDER__ macro. */
> +#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
> + defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_PDP_ENDIAN__)
> +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +#define PLUGIN_LITTLE_ENDIAN 1
> +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> +#define PLUGIN_BIG_ENDIAN 1
> +#elif __BYTE_ORDER__ == __ORDER_PDP_ENDIAN__
> +#define PLUGIN_PDP_ENDIAN 1
> +#endif
> +#else
> +/* Older GCC releases (<4.6.0) can make detection from glibc macros. */
> +#if defined(__GLIBC__) || defined(__GNU_LIBRARY__) || defined(__ANDROID__)
> +#include <endian.h>
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> +#define PLUGIN_LITTLE_ENDIAN 1
> +#elif __BYTE_ORDER == __BIG_ENDIAN
> +#define PLUGIN_BIG_ENDIAN 1
> +#endif
This will definePLUGIN_BIG_ENDIAN.
> +#endif
> +/* Include all necessary header files based on target. */
> +#if defined(__SVR4) && defined(__sun)
> +#include <sys/byteorder.h>
> +#endif
> +#if defined(__FreeBSD__) || defined(__NetBSD__) || \
> + defined(__DragonFly__) || defined(__minix)
> +#include <sys/endian.h>
> +#endif
> +#if defined(__OpenBSD__)
> +#include <machine/endian.h>
> +#endif
The above headers will not be included.
> +/* Detect endianess based on _BYTE_ORDER. */
> +#if _BYTE_ORDER == _LITTLE_ENDIAN
So most likely _BYTE_ORDER and _LITTLE_ENDIAN macros will not be defined.
Which means this will be handled as #if 0 == 0 and override the
> +#define PLUGIN_LITTLE_ENDIAN 1
will define also PLUGIN_LITTLE_ENDIAN.
> +#elif _BYTE_ORDER == _BIG_ENDIAN
> +#define PLUGIN_BIG_ENDIAN 1
> +#endif
> +/* Detect based on _WIN32. */
> +#if defined(_WIN32)
> +#define PLUGIN_LITTLE_ENDIAN 1
> +#endif
> +/* Fallback to __BIG_ENDIAN__ and __LITTLE_ENDIAN__ */
> +#ifdef __LITTLE_ENDIAN__
> +#define PLUGIN_LITTLE_ENDIAN 1
> +#endif
> +#ifdef __BIG_ENDIAN__
> +#define PLUGIN_BIG_ENDIAN 1
> +#endif
> +#endif
and the above isn't really a fallback, because it isn't guarded with
PLUGIN_*_ENDIAN not being defined yet.
Jakub
