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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 $Id$
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 ])