aclocal.m4

用C语言实现的JPEG编码

mkdir conftest
cd conftest
echo "int some_variable = 0;" > conftest.$ac_ext
mkdir out
# According to Tom Tromey, Ian Lance Taylor reported there are C compilers
# that will create temporary files in the current directory regardless of
# the output directory.  Thus, making CWD read-only will cause this test
# to fail, enabling locking or at least warning the user not to do parallel
# builds.
chmod -w .
save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -o out/conftest2.$ac_objext"
compiler_c_o=no
if { (eval echo configure:__oline__: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>out/conftest.err; } && test -s out/conftest2.$ac_objext; then
  # The compiler can only warn and ignore the option if not recognized
  # So say no if there are warnings
  if test -s out/conftest.err; then
    lt_cv_compiler_c_o=no
  else
    lt_cv_compiler_c_o=yes
  fi
else
  # Append any errors to the config.log.
  cat out/conftest.err 1>&AC_FD_CC
  lt_cv_compiler_c_o=no
fi
CFLAGS="$save_CFLAGS"
chmod u+w .
$rm conftest* out/*
rmdir out
cd ..
rmdir conftest
$rm -r conftest 2>/dev/null
])
compiler_c_o=$lt_cv_compiler_c_o
AC_MSG_RESULT([$compiler_c_o])

if test x"$compiler_c_o" = x"yes"; then
  # Check to see if we can write to a .lo
  AC_MSG_CHECKING([if $compiler supports -c -o file.lo])
  AC_CACHE_VAL([lt_cv_compiler_o_lo], [
  lt_cv_compiler_o_lo=no
  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS -c -o conftest.lo"
  save_objext="$ac_objext"
  ac_objext=lo
  AC_TRY_COMPILE([], [int some_variable = 0;], [dnl
    # The compiler can only warn and ignore the option if not recognized
    # So say no if there are warnings
    if test -s conftest.err; then
      lt_cv_compiler_o_lo=no
    else
      lt_cv_compiler_o_lo=yes
    fi
  ])
  ac_objext="$save_objext"
  CFLAGS="$save_CFLAGS"
  ])
  compiler_o_lo=$lt_cv_compiler_o_lo
  AC_MSG_RESULT([$compiler_o_lo])
else
  compiler_o_lo=no
fi

# Check to see if we can do hard links to lock some files if needed
hard_links="nottested"
if test "$compiler_c_o" = no && test "$need_locks" != no; then
  # do not overwrite the value of need_locks provided by the user
  AC_MSG_CHECKING([if we can lock with hard links])
  hard_links=yes
  $rm conftest*
  ln conftest.a conftest.b 2>/dev/null && hard_links=no
  touch conftest.a
  ln conftest.a conftest.b 2>&5 || hard_links=no
  ln conftest.a conftest.b 2>/dev/null && hard_links=no
  AC_MSG_RESULT([$hard_links])
  if test "$hard_links" = no; then
    AC_MSG_WARN([\`$CC' does not support \`-c -o', so \`make -j' may be unsafe])
    need_locks=warn
  fi
else
  need_locks=no
fi

if test "$GCC" = yes; then
  # Check to see if options -fno-rtti -fno-exceptions are supported by compiler
  AC_MSG_CHECKING([if $compiler supports -fno-rtti -fno-exceptions])
  echo "int some_variable = 0;" > conftest.$ac_ext
  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS -fno-rtti -fno-exceptions -c conftest.$ac_ext"
  compiler_rtti_exceptions=no
  AC_TRY_COMPILE([], [int some_variable = 0;], [dnl
    # The compiler can only warn and ignore the option if not recognized
    # So say no if there are warnings
    if test -s conftest.err; then
      compiler_rtti_exceptions=no
    else
      compiler_rtti_exceptions=yes
    fi
  ])
  CFLAGS="$save_CFLAGS"
  AC_MSG_RESULT([$compiler_rtti_exceptions])

  if test "$compiler_rtti_exceptions" = "yes"; then
    no_builtin_flag=' -fno-builtin -fno-rtti -fno-exceptions'
  else
    no_builtin_flag=' -fno-builtin'
  fi
fi

# See if the linker supports building shared libraries.
AC_MSG_CHECKING([whether the linker ($LD) supports shared libraries])

allow_undefined_flag=
no_undefined_flag=
need_lib_prefix=unknown
need_version=unknown
# when you set need_version to no, make sure it does not cause -set_version
# flags to be left without arguments
archive_cmds=
archive_expsym_cmds=
old_archive_from_new_cmds=
old_archive_from_expsyms_cmds=
export_dynamic_flag_spec=
whole_archive_flag_spec=
thread_safe_flag_spec=
hardcode_into_libs=no
hardcode_libdir_flag_spec=
hardcode_libdir_separator=
hardcode_direct=no
hardcode_minus_L=no
hardcode_shlibpath_var=unsupported
runpath_var=
link_all_deplibs=unknown
always_export_symbols=no
export_symbols_cmds='$NM $libobjs $convenience | $global_symbol_pipe | sed '\''s/.* //'\'' | sort | uniq > $export_symbols'
# include_expsyms should be a list of space-separated symbols to be *always*
# included in the symbol list
include_expsyms=
# exclude_expsyms can be an egrep regular expression of symbols to exclude
# it will be wrapped by ` (' and `)$', so one must not match beginning or
# end of line.  Example: `a|bc|.*d.*' will exclude the symbols `a' and `bc',
# as well as any symbol that contains `d'.
exclude_expsyms="_GLOBAL_OFFSET_TABLE_"
# Although _GLOBAL_OFFSET_TABLE_ is a valid symbol C name, most a.out
# platforms (ab)use it in PIC code, but their linkers get confused if
# the symbol is explicitly referenced.  Since portable code cannot
# rely on this symbol name, it's probably fine to never include it in
# preloaded symbol tables.
extract_expsyms_cmds=

case $host_os in
cygwin* | mingw* | pw32*)
  # FIXME: the MSVC++ port hasn't been tested in a loooong time
  # When not using gcc, we currently assume that we are using
  # Microsoft Visual C++.
  if test "$GCC" != yes; then
    with_gnu_ld=no
  fi
  ;;
openbsd*)
  with_gnu_ld=no
  ;;
esac

ld_shlibs=yes
if test "$with_gnu_ld" = yes; then
  # If archive_cmds runs LD, not CC, wlarc should be empty
  wlarc='${wl}'

  # See if GNU ld supports shared libraries.
  case $host_os in
  aix3* | aix4* | aix5*)
    # On AIX, the GNU linker is very broken
    # Note:Check GNU linker on AIX 5-IA64 when/if it becomes available.
    ld_shlibs=no
    cat <<EOF 1>&2

*** Warning: the GNU linker, at least up to release 2.9.1, is reported
*** to be unable to reliably create shared libraries on AIX.
*** Therefore, libtool is disabling shared libraries support.  If you
*** really care for shared libraries, you may want to modify your PATH
*** so that a non-GNU linker is found, and then restart.

EOF
    ;;

  amigaos*)
    archive_cmds='$rm $output_objdir/a2ixlibrary.data~$echo "#define NAME $libname" > $output_objdir/a2ixlibrary.data~$echo "#define LIBRARY_ID 1" >> $output_objdir/a2ixlibrary.data~$echo "#define VERSION $major" >> $output_objdir/a2ixlibrary.data~$echo "#define REVISION $revision" >> $output_objdir/a2ixlibrary.data~$AR $AR_FLAGS $lib $libobjs~$RANLIB $lib~(cd $output_objdir && a2ixlibrary -32)'
    hardcode_libdir_flag_spec='-L$libdir'
    hardcode_minus_L=yes

    # Samuel A. Falvo II <[e-mail]> reports
    # that the semantics of dynamic libraries on AmigaOS, at least up
    # to version 4, is to share data among multiple programs linked
    # with the same dynamic library.  Since this doesn't match the
    # behavior of shared libraries on other platforms, we can use
    # them.
    ld_shlibs=no
    ;;

  beos*)
    if $LD --help 2>&1 | egrep ': supported targets:.* elf' > /dev/null; then
      allow_undefined_flag=unsupported
      # Joseph Beckenbach <[e-mail]> says some releases of gcc
      # support --undefined.  This deserves some investigation.  FIXME
      archive_cmds='$CC -nostart $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname -o $lib'
    else
      ld_shlibs=no
    fi
    ;;

  cygwin* | mingw* | pw32*)
    # hardcode_libdir_flag_spec is actually meaningless, as there is
    # no search path for DLLs.
    hardcode_libdir_flag_spec='-L$libdir'
    allow_undefined_flag=unsupported
    always_export_symbols=yes

    extract_expsyms_cmds='test -f $output_objdir/impgen.c || \
      sed -e "/^# \/\* impgen\.c starts here \*\//,/^# \/\* impgen.c ends here \*\// { s/^# //;s/^# *$//; p; }" -e d < $''0 > $output_objdir/impgen.c~
      test -f $output_objdir/impgen.exe || (cd $output_objdir && \
      if test "x$HOST_CC" != "x" ; then $HOST_CC -o impgen impgen.c ; \
      else $CC -o impgen impgen.c ; fi)~
      $output_objdir/impgen $dir/$soroot > $output_objdir/$soname-def'

    old_archive_from_expsyms_cmds='$DLLTOOL --as=$AS --dllname $soname --def $output_objdir/$soname-def --output-lib $output_objdir/$newlib'

    # cygwin and mingw dlls have different entry points and sets of symbols
    # to exclude.
    # FIXME: what about values for MSVC?
    dll_entry=__cygwin_dll_entry@12
    dll_exclude_symbols=DllMain@12,_cygwin_dll_entry@12,_cygwin_noncygwin_dll_entry@12~
    case $host_os in
    mingw*)
      # mingw values
      dll_entry=_DllMainCRTStartup@12
      dll_exclude_symbols=DllMain@12,DllMainCRTStartup@12,DllEntryPoint@12~
      ;;
    esac

    # mingw and cygwin differ, and it's simplest to just exclude the union
    # of the two symbol sets.
    dll_exclude_symbols=DllMain@12,_cygwin_dll_entry@12,_cygwin_noncygwin_dll_entry@12,DllMainCRTStartup@12,DllEntryPoint@12

    # recent cygwin and mingw systems supply a stub DllMain which the user
    # can override, but on older systems we have to supply one (in ltdll.c)
    if test "x$lt_cv_need_dllmain" = "xyes"; then
      ltdll_obj='$output_objdir/$soname-ltdll.'"$ac_objext "
      ltdll_cmds='test -f $output_objdir/$soname-ltdll.c || sed -e "/^# \/\* ltdll\.c starts here \*\//,/^# \/\* ltdll.c ends here \*\// { s/^# //; p; }" -e d < $''0 > $output_objdir/$soname-ltdll.c~
	test -f $output_objdir/$soname-ltdll.$ac_objext || (cd $output_objdir && $CC -c $soname-ltdll.c)~'
    else
      ltdll_obj=
      ltdll_cmds=
    fi

    # Extract the symbol export list from an `--export-all' def file,
    # then regenerate the def file from the symbol export list, so that
    # the compiled dll only exports the symbol export list.
    # Be careful not to strip the DATA tag left be newer dlltools.
    export_symbols_cmds="$ltdll_cmds"'
      $DLLTOOL --export-all --exclude-symbols '$dll_exclude_symbols' --output-def $output_objdir/$soname-def '$ltdll_obj'$libobjs $convenience~
      sed -e "1,/EXPORTS/d" -e "s/ @ [[0-9]]*//" -e "s/ *;.*$//" < $output_objdir/$soname-def > $export_symbols'

    # If the export-symbols file already is a .def file (1st line
    # is EXPORTS), use it as is.
    # If DATA tags from a recent dlltool are present, honour them!
    archive_expsym_cmds='if test "x`head -1 $export_symbols`" = xEXPORTS; then
	cp $export_symbols $output_objdir/$soname-def;
      else
	echo EXPORTS > $output_objdir/$soname-def;
	_lt_hint=1;
	cat $export_symbols | while read symbol; do
	 set dummy \$symbol;
	 case \[$]# in
	   2) echo "   \[$]2 @ \$_lt_hint ; " >> $output_objdir/$soname-def;;
	   *) echo "     \[$]2 @ \$_lt_hint \[$]3 ; " >> $output_objdir/$soname-def;;
	 esac;
	 _lt_hint=`expr 1 + \$_lt_hint`;
	done;
      fi~
      '"$ltdll_cmds"'
      $CC -Wl,--base-file,$output_objdir/$soname-base '$lt_cv_cc_dll_switch' -Wl,-e,'$dll_entry' -o $output_objdir/$soname '$ltdll_obj'$libobjs $deplibs $compiler_flags~
      $DLLTOOL --as=$AS --dllname $soname --exclude-symbols '$dll_exclude_symbols' --def $output_objdir/$soname-def --base-file $output_objdir/$soname-base --output-exp $output_objdir/$soname-exp~
      $CC -Wl,--base-file,$output_objdir/$soname-base $output_objdir/$soname-exp '$lt_cv_cc_dll_switch' -Wl,-e,'$dll_entry' -o $output_objdir/$soname '$ltdll_obj'$libobjs $deplibs $compiler_flags~
      $DLLTOOL --as=$AS --dllname $soname --exclude-symbols '$dll_exclude_symbols' --def $output_objdir/$soname-def --base-file $output_objdir/$soname-base --output-exp $output_objdir/$soname-exp --output-lib $output_objdir/$libname.dll.a~
      $CC $output_objdir/$soname-exp '$lt_cv_cc_dll_switch' -Wl,-e,'$dll_entry' -o $output_objdir/$soname '$ltdll_obj'$libobjs $deplibs $compiler_flags'
    ;;

  netbsd*)
    if echo __ELF__ | $CC -E - | grep __ELF__ >/dev/null; then
      archive_cmds='$LD -Bshareable $libobjs $deplibs $linker_flags -o $lib'
      wlarc=
    else
      archive_cmds='$CC -shared -nodefaultlibs $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname -o $lib'
      archive_expsym_cmds='$CC -shared -nodefaultlibs $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname ${wl}-retain-symbols-file $wl$export_symbols -o $lib'
    fi
    ;;

  solaris* | sysv5*)
    if $LD -v 2>&1 | egrep 'BFD 2\.8' > /dev/null; then
      ld_shlibs=no
      cat <<EOF 1>&2

*** Warning: The releases 2.8.* of the GNU linker cannot reliably
*** create shared libraries on Solaris systems.  Therefore, libtool
*** is disabling shared libraries support.  We urge you to upgrade GNU
*** binutils to release 2.9.1 or newer.  Another option is to modify
*** your PATH or compiler configuration so that the native linker is
*** used, and then restart.

EOF
    elif $LD --help 2>&1 | egrep ': supported targets:.* elf' > /dev/null; then
      archive_cmds='$CC -shared $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname -o $lib'
      archive_expsym_cmds='$CC -shared $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname ${wl}-retain-symbols-file $wl$export_symbols -o $lib'
    else
      ld_shlibs=no
    fi
    ;;

  sunos4*)
    archive_cmds='$LD -assert pure-text -Bshareable -o $lib $libobjs $deplibs $linker_flags'
    wlarc=
    hardcode_direct=yes
    hardcode_shlibpath_var=no
    ;;

  *)
    if $LD --help 2>&1 | egrep ': supported targets:.* elf' > /dev/null; then
      archive_cmds='$CC -shared $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname -o $lib'
      archive_expsym_cmds='$CC -shared $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname ${wl}-retain-symbols-file $wl$export_symbols -o $lib'
    else
      ld_shlibs=no
    fi
    ;;
  esac

  if test "$ld_shlibs" = yes; then
    runpath_var=LD_RUN_PATH
    hardcode_libdir_flag_spec='${wl}--rpath ${wl}$libdir'
    export_dynamic_flag_spec='${wl}--export-dynamic'
    case $host_os in
    cygwin* | mingw* | pw32*)
      # dlltool doesn't understand --whole-archive et. al.
      whole_archive_flag_spec=
      ;;
    *)
      # ancient GNU ld didn't support --whole-archive et. al.
      if $LD --help 2>&1 | egrep 'no-whole-archive' > /dev/null; then
	whole_archive_flag_spec="$wlarc"'--whole-archive$convenience '"$wlarc"'--no-whole-archive'
      else
	whole_archive_flag_spec=
      fi
      ;;
    esac
  fi
else
  # PORTME fill in a description of your system's linker (not GNU ld)
  case $host_os in
  aix3*)
    allow_undefined_flag=unsupported
    always_export_symbols=yes
    archive_expsym_cmds='$LD -o $output_objdir/$soname $libobjs $deplibs $linker_flags -bE:$export_symbols -T512 -H512 -bM:SRE~$AR $AR_FLAGS $lib $output_objdir/$soname'
    # Note: this linker hardcodes the directories in LIBPATH if there
    # are no directories specified by -L.
    hardcode_minus_L=yes
    if test "$GCC" = yes && test -z "$link_static_flag"; then
      # Neither direct hardcoding nor static linking is supported with a
      # broken collect2.
      hardcode_direct=unsupported
    fi
    ;;

  aix4* | aix5*)
    if test "$host_cpu" = ia64; then
      # On IA64, the linker does run time linking by default, so we don't
      # have to do anything special.
      aix_use_runtimelinking=no
      exp_sym_flag='-Bexport'
      no_entry_flag=""
    else
      aix_use_runtimelinking=no

      # Test if we are trying to use run time linking or normal
      # AIX style linking. If -brtl is somewhere in LDFLAGS, we