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    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 1.1.1.1 2012/02/21 23:00:54 misho 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: ])