Adding cross-compile safe BIGENDIAN test for autoconf. Original source:

http://cryp.to/autoconf-archive/Cross_Compilation/ac_c_bigendian_cross.html

This is part of SF patch #431342.

diff --git a/expat/conftools/ac_c_bigendian_cross.m4 b/expat/conftools/ac_c_bigendian_cross.m4
new file mode 100644 (file)
index 0000000..952c854
--- /dev/null
+++ b/expat/conftools/ac_c_bigendian_cross.m4
@@ -0,0 +1,81 @@
+dnl @synopsis AC_C_BIGENDIAN_CROSS
+dnl
+dnl Check endianess even when crosscompiling
+dnl (partially based on the original AC_C_BIGENDIAN).
+dnl
+dnl The implementation will create a binary, and instead of running
+dnl the binary it will be grep'ed for some symbols that will look
+dnl different for different endianess of the binary.
+dnl
+dnl @version $Id: ac_c_bigendian_cross.m4,v 1.2 2001/03/16 09:12:52 simons Exp $
+dnl @author Guido Draheim <guidod@gmx.de>
+dnl
+AC_DEFUN([AC_C_BIGENDIAN_CROSS],
+[AC_CACHE_CHECK(whether byte ordering is bigendian, ac_cv_c_bigendian,
+[ac_cv_c_bigendian=unknown
+# See if sys/param.h defines the BYTE_ORDER macro.
+AC_TRY_COMPILE([#include <sys/types.h>
+#include <sys/param.h>], [
+#if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
+ bogus endian macros
+#endif], [# It does; now see whether it defined to BIG_ENDIAN or not.
+AC_TRY_COMPILE([#include <sys/types.h>
+#include <sys/param.h>], [
+#if BYTE_ORDER != BIG_ENDIAN
+ not big endian
+#endif], ac_cv_c_bigendian=yes, ac_cv_c_bigendian=no)])
+if test $ac_cv_c_bigendian = unknown; then
+AC_TRY_RUN([main () {
+  /* Are we little or big endian?  From Harbison&Steele.  */
+  union
+  {
+    long l;
+    char c[sizeof (long)];
+  } u;
+  u.l = 1;
+  exit (u.c[sizeof (long) - 1] == 1);
+}], ac_cv_c_bigendian=no, ac_cv_c_bigendian=yes,
+[ echo $ac_n "cross-compiling... " 2>&AC_FD_MSG ])
+fi])
+if test $ac_cv_c_bigendian = unknown; then
+AC_MSG_CHECKING(to probe for byte ordering)
+[
+cat >conftest.c <<EOF
+short ascii_mm[] = { 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };
+short ascii_ii[] = { 0x694C, 0x5454, 0x656C, 0x6E45, 0x6944, 0x6E61, 0 };
+void _ascii() { char* s = (char*) ascii_mm; s = (char*) ascii_ii; }
+short ebcdic_ii[] = { 0x89D3, 0xE3E3, 0x8593, 0x95C5, 0x89C4, 0x9581, 0 };
+short ebcdic_mm[] = { 0xC2C9, 0xC785, 0x95C4, 0x8981, 0x95E2, 0xA8E2, 0 };
+void _ebcdic() { char* s = (char*) ebcdic_mm; s = (char*) ebcdic_ii; }
+int main() { _ascii (); _ebcdic (); return 0; }
+EOF
+] if test -f conftest.c ; then
+     if ${CC-cc} conftest.c -o conftest.o && test -f conftest.o ; then
+        if test `grep -l BIGenDianSyS conftest.o` ; then
+           echo $ac_n ' big endian probe OK, ' 1>&AC_FD_MSG
+           ac_cv_c_bigendian=yes
+        fi
+        if test `grep -l LiTTleEnDian conftest.o` ; then
+           echo $ac_n ' little endian probe OK, ' 1>&AC_FD_MSG
+           if test $ac_cv_c_bigendian = yes ; then
+            ac_cv_c_bigendian=unknown;
+           else
+            ac_cv_c_bigendian=no
+           fi
+        fi
+        echo $ac_n 'guessing bigendian ...  ' >&AC_FD_MSG
+     fi
+  fi
+AC_MSG_RESULT($ac_cv_c_bigendian)
+fi
+if test $ac_cv_c_bigendian = yes; then
+  AC_DEFINE(WORDS_BIGENDIAN, 1, [whether byteorder is bigendian])
+  BYTEORDER=4321
+else
+  BYTEORDER=1234
+fi
+AC_DEFINE_UNQUOTED(BYTEORDER, $BYTEORDER, [1234 = LIL_ENDIAN, 4321 = BIGENDIAN])
+if test $ac_cv_c_bigendian = unknown; then
+  AC_MSG_ERROR(unknown endianess - sorry, please pre-set ac_cv_c_bigendian)
+fi
+])