109f8790f9
http://cryp.to/autoconf-archive/Cross_Compilation/ac_c_bigendian_cross.html This is part of SF patch #431342.
82 lines
2.9 KiB
Plaintext
82 lines
2.9 KiB
Plaintext
dnl @synopsis AC_C_BIGENDIAN_CROSS
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dnl
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dnl Check endianess even when crosscompiling
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dnl (partially based on the original AC_C_BIGENDIAN).
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dnl
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dnl The implementation will create a binary, and instead of running
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dnl the binary it will be grep'ed for some symbols that will look
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dnl different for different endianess of the binary.
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dnl
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dnl @version $Id: ac_c_bigendian_cross.m4,v 1.2 2001/03/16 09:12:52 simons Exp $
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dnl @author Guido Draheim <guidod@gmx.de>
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dnl
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AC_DEFUN([AC_C_BIGENDIAN_CROSS],
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[AC_CACHE_CHECK(whether byte ordering is bigendian, ac_cv_c_bigendian,
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[ac_cv_c_bigendian=unknown
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# See if sys/param.h defines the BYTE_ORDER macro.
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AC_TRY_COMPILE([#include <sys/types.h>
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#include <sys/param.h>], [
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#if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
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bogus endian macros
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#endif], [# It does; now see whether it defined to BIG_ENDIAN or not.
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AC_TRY_COMPILE([#include <sys/types.h>
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#include <sys/param.h>], [
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#if BYTE_ORDER != BIG_ENDIAN
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not big endian
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#endif], ac_cv_c_bigendian=yes, ac_cv_c_bigendian=no)])
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if test $ac_cv_c_bigendian = unknown; then
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AC_TRY_RUN([main () {
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/* Are we little or big endian? From Harbison&Steele. */
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union
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{
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long l;
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char c[sizeof (long)];
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} u;
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u.l = 1;
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exit (u.c[sizeof (long) - 1] == 1);
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}], ac_cv_c_bigendian=no, ac_cv_c_bigendian=yes,
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[ echo $ac_n "cross-compiling... " 2>&AC_FD_MSG ])
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fi])
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if test $ac_cv_c_bigendian = unknown; then
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AC_MSG_CHECKING(to probe for byte ordering)
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[
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cat >conftest.c <<EOF
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short ascii_mm[] = { 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };
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short ascii_ii[] = { 0x694C, 0x5454, 0x656C, 0x6E45, 0x6944, 0x6E61, 0 };
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void _ascii() { char* s = (char*) ascii_mm; s = (char*) ascii_ii; }
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short ebcdic_ii[] = { 0x89D3, 0xE3E3, 0x8593, 0x95C5, 0x89C4, 0x9581, 0 };
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short ebcdic_mm[] = { 0xC2C9, 0xC785, 0x95C4, 0x8981, 0x95E2, 0xA8E2, 0 };
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void _ebcdic() { char* s = (char*) ebcdic_mm; s = (char*) ebcdic_ii; }
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int main() { _ascii (); _ebcdic (); return 0; }
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EOF
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] if test -f conftest.c ; then
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if ${CC-cc} conftest.c -o conftest.o && test -f conftest.o ; then
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if test `grep -l BIGenDianSyS conftest.o` ; then
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echo $ac_n ' big endian probe OK, ' 1>&AC_FD_MSG
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ac_cv_c_bigendian=yes
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fi
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if test `grep -l LiTTleEnDian conftest.o` ; then
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echo $ac_n ' little endian probe OK, ' 1>&AC_FD_MSG
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if test $ac_cv_c_bigendian = yes ; then
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ac_cv_c_bigendian=unknown;
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else
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ac_cv_c_bigendian=no
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fi
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fi
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echo $ac_n 'guessing bigendian ... ' >&AC_FD_MSG
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fi
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fi
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AC_MSG_RESULT($ac_cv_c_bigendian)
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fi
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if test $ac_cv_c_bigendian = yes; then
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AC_DEFINE(WORDS_BIGENDIAN, 1, [whether byteorder is bigendian])
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BYTEORDER=4321
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else
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BYTEORDER=1234
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fi
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AC_DEFINE_UNQUOTED(BYTEORDER, $BYTEORDER, [1234 = LIL_ENDIAN, 4321 = BIGENDIAN])
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if test $ac_cv_c_bigendian = unknown; then
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AC_MSG_ERROR(unknown endianess - sorry, please pre-set ac_cv_c_bigendian)
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fi
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])
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