1 dnl @synopsis AC_C_BIGENDIAN_CROSS

     2 dnl

     3 dnl Check endianess even when crosscompiling

     4 dnl (partially based on the original AC_C_BIGENDIAN).

     5 dnl

     6 dnl The implementation will create a binary, and instead of running

     7 dnl the binary it will be grep'ed for some symbols that will look

     8 dnl different for different endianess of the binary.

     9 dnl

    10 dnl @version $Id: ac_c_bigendian_cross.m4,v 1.2 2001/10/01 20:03:13 fdrake Exp $

    11 dnl @author Guido Draheim <guidod@gmx.de>

    12 dnl

    13 AC_DEFUN([AC_C_BIGENDIAN_CROSS],

    14 [AC_CACHE_CHECK(whether byte ordering is bigendian, ac_cv_c_bigendian,

    15 [ac_cv_c_bigendian=unknown

    16 # See if sys/param.h defines the BYTE_ORDER macro.

    17 AC_TRY_COMPILE([#include <sys/types.h>

    18 #include <sys/param.h>], [

    19 #if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN

    20  bogus endian macros

    21 #endif], [# It does; now see whether it defined to BIG_ENDIAN or not.

    22 AC_TRY_COMPILE([#include <sys/types.h>

    23 #include <sys/param.h>], [

    24 #if BYTE_ORDER != BIG_ENDIAN

    25  not big endian

    26 #endif], ac_cv_c_bigendian=yes, ac_cv_c_bigendian=no)])

    27 if test $ac_cv_c_bigendian = unknown; then

    28 AC_TRY_RUN([main () {

    29   /* Are we little or big endian?  From Harbison&Steele.  */

    30   union

    31   {

    32     long l;

    33     char c[sizeof (long)];

    34   } u;

    35   u.l = 1;

    36   exit (u.c[sizeof (long) - 1] == 1);

    37 }], ac_cv_c_bigendian=no, ac_cv_c_bigendian=yes,

    38 [ echo $ac_n "cross-compiling... " 2>&AC_FD_MSG ])

    39 fi])

    40 if test $ac_cv_c_bigendian = unknown; then

    41 AC_MSG_CHECKING(to probe for byte ordering)

    42 [

    43 cat >conftest.c <<EOF

    44 short ascii_mm[] = { 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };

    45 short ascii_ii[] = { 0x694C, 0x5454, 0x656C, 0x6E45, 0x6944, 0x6E61, 0 };

    46 void _ascii() { char* s = (char*) ascii_mm; s = (char*) ascii_ii; }

    47 short ebcdic_ii[] = { 0x89D3, 0xE3E3, 0x8593, 0x95C5, 0x89C4, 0x9581, 0 };

    48 short ebcdic_mm[] = { 0xC2C9, 0xC785, 0x95C4, 0x8981, 0x95E2, 0xA8E2, 0 };

    49 void _ebcdic() { char* s = (char*) ebcdic_mm; s = (char*) ebcdic_ii; }

    50 int main() { _ascii (); _ebcdic (); return 0; }

    51 EOF

    52 ] if test -f conftest.c ; then

    53      if ${CC-cc} -c conftest.c -o conftest.o && test -f conftest.o ; then

    54         if test `grep -l BIGenDianSyS conftest.o` ; then

    55            echo $ac_n ' big endian probe OK, ' 1>&AC_FD_MSG

    56            ac_cv_c_bigendian=yes

    57         fi

    58         if test `grep -l LiTTleEnDian conftest.o` ; then

    59            echo $ac_n ' little endian probe OK, ' 1>&AC_FD_MSG

    60            if test $ac_cv_c_bigendian = yes ; then

    61             ac_cv_c_bigendian=unknown;

    62            else

    63             ac_cv_c_bigendian=no

    64            fi

    65         fi

    66         echo $ac_n 'guessing bigendian ...  ' >&AC_FD_MSG

    67      fi

    68   fi

    69 AC_MSG_RESULT($ac_cv_c_bigendian)

    70 fi

    71 if test $ac_cv_c_bigendian = yes; then

    72   AC_DEFINE(WORDS_BIGENDIAN, 1, [whether byteorder is bigendian])

    73   BYTEORDER=4321

    74 else

    75   BYTEORDER=1234

    76 fi

    77 AC_DEFINE_UNQUOTED(BYTEORDER, $BYTEORDER, [1234 = LIL_ENDIAN, 4321 = BIGENDIAN])

    78 if test $ac_cv_c_bigendian = unknown; then

    79   AC_MSG_ERROR(unknown endianess - sorry, please pre-set ac_cv_c_bigendian)

    80 fi

    81 ])