This provides the endian conversion functions form endian.h on Windows, Linux, *BSD, and Mac OS X. You still need to use -std=gnu99 instead of -std=c99 for gcc. The functions might actually be macros. Functions: htobe16, htole16, be16toh, le16toh, htobe32, htole32, be32toh, le32toh, htobe64, htole64, be64toh, le64toh. License: I hereby put "port…

portable_endian.h

// "License": Public Domain
// I, Mathias Panzenböck, place this file hereby into the public domain. Use it at your own risk for whatever you like.
// In case there are jurisdictions that don't support putting things in the public domain you can also consider it to
// be "dual licensed" under the BSD, MIT and Apache licenses, if you want to. This code is trivial anyway. Consider it
// an example on how to get the endian conversion functions on different platforms.

#ifndef PORTABLE_ENDIAN_H__
#define PORTABLE_ENDIAN_H__

#if (defined(_WIN16) || defined(_WIN32) || defined(_WIN64)) && !defined(__WINDOWS__)

#	define __WINDOWS__

#endif

#if defined(__linux__) || defined(__CYGWIN__)

#	include <endian.h>

#elif defined(__APPLE__)

#	include <libkern/OSByteOrder.h>

#	define htobe16(x) OSSwapHostToBigInt16(x)
#	define htole16(x) OSSwapHostToLittleInt16(x)
#	define be16toh(x) OSSwapBigToHostInt16(x)
#	define le16toh(x) OSSwapLittleToHostInt16(x)
 
#	define htobe32(x) OSSwapHostToBigInt32(x)
#	define htole32(x) OSSwapHostToLittleInt32(x)
#	define be32toh(x) OSSwapBigToHostInt32(x)
#	define le32toh(x) OSSwapLittleToHostInt32(x)
 
#	define htobe64(x) OSSwapHostToBigInt64(x)
#	define htole64(x) OSSwapHostToLittleInt64(x)
#	define be64toh(x) OSSwapBigToHostInt64(x)
#	define le64toh(x) OSSwapLittleToHostInt64(x)

#	define __BYTE_ORDER    BYTE_ORDER
#	define __BIG_ENDIAN    BIG_ENDIAN
#	define __LITTLE_ENDIAN LITTLE_ENDIAN
#	define __PDP_ENDIAN    PDP_ENDIAN

#elif defined(__OpenBSD__)

#	include <sys/endian.h>

#elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)

#	include <sys/endian.h>

#	define be16toh(x) betoh16(x)
#	define le16toh(x) letoh16(x)

#	define be32toh(x) betoh32(x)
#	define le32toh(x) letoh32(x)

#	define be64toh(x) betoh64(x)
#	define le64toh(x) letoh64(x)

#elif defined(__WINDOWS__)

#	include <winsock2.h>
#	include <sys/param.h>

#	if BYTE_ORDER == LITTLE_ENDIAN

#		define htobe16(x) htons(x)
#		define htole16(x) (x)
#		define be16toh(x) ntohs(x)
#		define le16toh(x) (x)
 
#		define htobe32(x) htonl(x)
#		define htole32(x) (x)
#		define be32toh(x) ntohl(x)
#		define le32toh(x) (x)
 
#		define htobe64(x) htonll(x)
#		define htole64(x) (x)
#		define be64toh(x) ntohll(x)
#		define le64toh(x) (x)

#	elif BYTE_ORDER == BIG_ENDIAN

		/* that would be xbox 360 */
#		define htobe16(x) (x)
#		define htole16(x) __builtin_bswap16(x)
#		define be16toh(x) (x)
#		define le16toh(x) __builtin_bswap16(x)
 
#		define htobe32(x) (x)
#		define htole32(x) __builtin_bswap32(x)
#		define be32toh(x) (x)
#		define le32toh(x) __builtin_bswap32(x)
 
#		define htobe64(x) (x)
#		define htole64(x) __builtin_bswap64(x)
#		define be64toh(x) (x)
#		define le64toh(x) __builtin_bswap64(x)

#	else

#		error byte order not supported

#	endif

#	define __BYTE_ORDER    BYTE_ORDER
#	define __BIG_ENDIAN    BIG_ENDIAN
#	define __LITTLE_ENDIAN LITTLE_ENDIAN
#	define __PDP_ENDIAN    PDP_ENDIAN

#else

#	error platform not supported

#endif

#endif