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Annotation of embedaddon/expat/conftools/ac_c_bigendian_cross.m4, revision 1.1.1.1

1.1       misho       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: ])