dnl @synopsis AC_C_FIND_ENDIAN
dnl
dnl Determine endian-ness of target processor.
dnl @version 1.1	Mar 03 2002
dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
dnl
dnl Majority written from scratch to replace the standard autoconf macro 
dnl AC_C_BIGENDIAN. Only part remaining from the original it the invocation
dnl of the AC_TRY_RUN macro.
dnl
dnl Permission to use, copy, modify, distribute, and sell this file for any 
dnl purpose is hereby granted without fee, provided that the above copyright 
dnl and this permission notice appear in all copies.  No representations are
dnl made about the suitability of this software for any purpose.  It is 
dnl provided "as is" without express or implied warranty.

dnl Find endian-ness in the following way:
dnl    1) Look in <endian.h>.
dnl    2) If 1) fails, look in <sys/types.h> and <sys/param.h>.
dnl    3) If 1) and 2) fails and not cross compiling run a test program.
dnl    4) If 1) and 2) fails and cross compiling then guess based on target.

AC_DEFUN([AC_C_FIND_ENDIAN],
[AC_CACHE_CHECK(processor byte ordering, 
	ac_cv_c_byte_order,

# Initialize to unknown
ac_cv_c_byte_order=unknown

if test x$ac_cv_header_endian_h = xyes ; then

	# First try <endian.h> which should set BYTE_ORDER.

	[AC_TRY_LINK([
		#include <endian.h>
		#if BYTE_ORDER != LITTLE_ENDIAN
			not big endian
		#endif
		], return 0 ;, 
			ac_cv_c_byte_order=little
		)]
				
	[AC_TRY_LINK([
		#include <endian.h>
		#if BYTE_ORDER != BIG_ENDIAN
			not big endian
		#endif
		], return 0 ;, 
			ac_cv_c_byte_order=big
		)]

	fi

if test $ac_cv_c_byte_order = unknown ; then

	[AC_TRY_LINK([
		#include <sys/types.h>
		#include <sys/param.h>
		#if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
			bogus endian macros
		#endif
		], return 0 ;, 

		[AC_TRY_LINK([
			#include <sys/types.h>
			#include <sys/param.h>
			#if BYTE_ORDER != LITTLE_ENDIAN
				not big endian
			#endif
			], return 0 ;, 
				ac_cv_c_byte_order=little
			)]
				
		[AC_TRY_LINK([
			#include <sys/types.h>
			#include <sys/param.h>
			#if BYTE_ORDER != LITTLE_ENDIAN
				not big endian
			#endif
			], return 0 ;, 
				ac_cv_c_byte_order=little
			)]

		)]

 	fi

if test $ac_cv_c_byte_order = unknown ; then
	if test $cross_compiling = yes ; then
		# This is the last resort. Try to guess the target processor endian-ness
		# by looking at the target CPU type.	
		[
		case "$target_cpu" in
			alpha* | i?86* | mipsel* | ia64*)
				ac_cv_c_byte_order=little
				;;
			
			m68* | mips* | powerpc* | hppa* | sparc*)
				ac_cv_c_byte_order=big
				;;
	
			esac
		]
	else
		AC_TRY_RUN(
		[[
		int main (void) 
		{	/* Are we little or big endian?  From Harbison&Steele.  */
			union
			{	long l ;
				char c [sizeof (long)] ;
			} u ;
			u.l = 1 ;
			return (u.c [sizeof (long) - 1] == 1);
			}
			]], , ac_cv_c_byte_order=big, 
			)

		AC_TRY_RUN(
		[[int main (void) 
		{	/* Are we little or big endian?  From Harbison&Steele.  */
			union
			{	long l ;
				char c [sizeof (long)] ;
			} u ;
			u.l = 1 ;
			return (u.c [0] == 1);
			}]], , ac_cv_c_byte_order=little, 
			)
		fi	
	fi

)

if test $ac_cv_c_byte_order = big ; then
	ac_cv_c_big_endian=1
	ac_cv_c_little_endian=0
elif test $ac_cv_c_byte_order = little ; then
	ac_cv_c_big_endian=0
	ac_cv_c_little_endian=1
else
	ac_cv_c_big_endian=0
	ac_cv_c_little_endian=0

	AC_MSG_WARN([[*****************************************************************]])
	AC_MSG_WARN([[*** Not able to determine endian-ness of target processor.       ]])
	AC_MSG_WARN([[*** The constants CPU_IS_BIG_ENDIAN and CPU_IS_LITTLE_ENDIAN in  ]])
	AC_MSG_WARN([[*** src/config.h may need to be hand editied.                    ]])
	AC_MSG_WARN([[*****************************************************************]])
	fi

]
)# AC_C_FIND_ENDIAN


