ltconfig

MPEG-4编解码的实现(包括MPEG4视音频编解码)

      # On HP-UX, both CC and GCC only warn that PIC is supported... then they
      # create non-PIC objects.  So, if there were any warnings, we assume that
      # PIC is not supported.
      if test -s conftest.err; then
	echo "$ac_t"no 1>&6
	can_build_shared=no
	pic_flag=
      else
	echo "$ac_t"yes 1>&6
	pic_flag=" $pic_flag"
      fi
      ;;
    *)
      echo "$ac_t"yes 1>&6
      pic_flag=" $pic_flag"
      ;;
    esac
  else
    # Append any errors to the config.log.
    cat conftest.err 1>&5
    can_build_shared=no
    pic_flag=
    echo "$ac_t"no 1>&6
  fi
  CFLAGS="$save_CFLAGS"
  $rm conftest*
else
  echo "$ac_t"none 1>&6
fi

# Check to see if options -o and -c are simultaneously supported by compiler
echo $ac_n "checking if $compiler supports -c -o file.o... $ac_c" 1>&6
$rm -r conftest 2>/dev/null
mkdir conftest
cd conftest
$rm conftest*
echo "int some_variable = 0;" > conftest.c
mkdir out
# According to Tom Tromey, Ian Lance Taylor reported there are C compilers
# that will create temporary files in the current directory regardless of
# the output directory.  Thus, making CWD read-only will cause this test
# to fail, enabling locking or at least warning the user not to do parallel
# builds.
chmod -w .
save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -o out/conftest2.o"
echo "$progname:829: checking if $compiler supports -c -o file.o" >&5
if { (eval echo $progname:830: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>out/conftest.err; } && test -s out/conftest2.o; 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
      echo "$ac_t"no 1>&6
      compiler_c_o=no
    else
      echo "$ac_t"yes 1>&6
      compiler_c_o=yes
    fi
else
  # Append any errors to the config.log.
  cat out/conftest.err 1>&5
  compiler_c_o=no
  echo "$ac_t"no 1>&6
fi
CFLAGS="$save_CFLAGS"
chmod u+w .
$rm conftest* out/*
rmdir out
cd ..
rmdir conftest
$rm -r conftest 2>/dev/null

if test x"$compiler_c_o" = x"yes"; then
  # Check to see if we can write to a .lo
  echo $ac_n "checking if $compiler supports -c -o file.lo... $ac_c" 1>&6
  $rm conftest*
  echo "int some_variable = 0;" > conftest.c
  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS -c -o conftest.lo"
  echo "$progname:862: checking if $compiler supports -c -o file.lo" >&5
if { (eval echo $progname:863: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>conftest.err; } && test -s conftest.lo; then

    # 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
	echo "$ac_t"no 1>&6
	compiler_o_lo=no
      else
	echo "$ac_t"yes 1>&6
	compiler_o_lo=yes
      fi
  else
    # Append any errors to the config.log.
    cat conftest.err 1>&5
    compiler_o_lo=no
    echo "$ac_t"no 1>&6
  fi
  CFLAGS="$save_CFLAGS"
  $rm conftest*
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
  echo $ac_n "checking if we can lock with hard links... $ac_c" 1>&6
  hard_links=yes
  $rm conftest*
  ln conftest.a conftest.b 2>/dev/null && hard_links=no
  touch conftest.a
  ln conftest.a conftest.b 2>&5 || hard_links=no
  ln conftest.a conftest.b 2>/dev/null && hard_links=no
  echo "$ac_t$hard_links" 1>&6
  $rm conftest*
  if test "$hard_links" = no; then
    echo "*** WARNING: \`$CC' does not support \`-c -o', so \`make -j' may be unsafe" >&2
    need_locks=warn
  fi
else
  need_locks=no
fi

if test "$with_gcc" = yes; then
  # Check to see if options -fno-rtti -fno-exceptions are supported by compiler
  echo $ac_n "checking if $compiler supports -fno-rtti -fno-exceptions ... $ac_c" 1>&6
  $rm conftest*
  echo "int some_variable = 0;" > conftest.c
  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS -fno-rtti -fno-exceptions -c conftest.c"
  echo "$progname:914: checking if $compiler supports -fno-rtti -fno-exceptions" >&5
  if { (eval echo $progname:915: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>conftest.err; } && test -s conftest.o; then

    # 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
	echo "$ac_t"no 1>&6
	compiler_rtti_exceptions=no
      else
	echo "$ac_t"yes 1>&6
	compiler_rtti_exceptions=yes
      fi
  else
    # Append any errors to the config.log.
    cat conftest.err 1>&5
    compiler_rtti_exceptions=no
    echo "$ac_t"no 1>&6
  fi
  CFLAGS="$save_CFLAGS"
  $rm conftest*

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

# Check for any special shared library compilation flags.
if test -n "$special_shlib_compile_flags"; then
  echo "$progname: warning: \`$CC' requires \`$special_shlib_compile_flags' to build shared libraries" 1>&2
  if echo "$old_CC $old_CFLAGS " | egrep -e "[ 	]$special_shlib_compile_flags[ 	]" >/dev/null; then :
  else
    echo "$progname: add \`$special_shlib_compile_flags' to the CC or CFLAGS env variable and reconfigure" 1>&2
    can_build_shared=no
  fi
fi

echo $ac_n "checking if $compiler static flag $link_static_flag works... $ac_c" 1>&6
$rm conftest*
echo 'main(){return(0);}' > conftest.c
save_LDFLAGS="$LDFLAGS"
LDFLAGS="$LDFLAGS $link_static_flag"
echo "$progname:958: checking if $compiler static flag $link_static_flag works" >&5
if { (eval echo $progname:959: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
  echo "$ac_t$link_static_flag" 1>&6
else
  echo "$ac_t"none 1>&6
  link_static_flag=
fi
LDFLAGS="$save_LDFLAGS"
$rm conftest*

if test -z "$LN_S"; then
  # Check to see if we can use ln -s, or we need hard links.
  echo $ac_n "checking whether ln -s works... $ac_c" 1>&6
  $rm conftest.dat
  if ln -s X conftest.dat 2>/dev/null; then
    $rm conftest.dat
    LN_S="ln -s"
  else
    LN_S=ln
  fi
  if test "$LN_S" = "ln -s"; then
    echo "$ac_t"yes 1>&6
  else
    echo "$ac_t"no 1>&6
  fi
fi

# Make sure LD is an absolute path.
if test -z "$LD"; then
  ac_prog=ld
  if test "$with_gcc" = yes; then
    # Check if gcc -print-prog-name=ld gives a path.
    echo $ac_n "checking for ld used by GCC... $ac_c" 1>&6
    echo "$progname:991: checking for ld used by GCC" >&5
    ac_prog=`($CC -print-prog-name=ld) 2>&5`
    case "$ac_prog" in
    # Accept absolute paths.
    [\\/]* | [A-Za-z]:[\\/]*)
      re_direlt='/[^/][^/]*/\.\./'
      # Canonicalize the path of ld
      ac_prog=`echo $ac_prog| sed 's%\\\\%/%g'`
      while echo $ac_prog | grep "$re_direlt" > /dev/null 2>&1; do
	ac_prog=`echo $ac_prog| sed "s%$re_direlt%/%"`
      done
      test -z "$LD" && LD="$ac_prog"
      ;;
    "")
      # If it fails, then pretend we are not using GCC.
      ac_prog=ld
      ;;
    *)
      # If it is relative, then search for the first ld in PATH.
      with_gnu_ld=unknown
      ;;
    esac
  elif test "$with_gnu_ld" = yes; then
    echo $ac_n "checking for GNU ld... $ac_c" 1>&6
    echo "$progname:1015: checking for GNU ld" >&5
  else
    echo $ac_n "checking for non-GNU ld""... $ac_c" 1>&6
    echo "$progname:1018: checking for non-GNU ld" >&5
  fi

  if test -z "$LD"; then
    IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}${PATH_SEPARATOR}"
    for ac_dir in $PATH; do
      test -z "$ac_dir" && ac_dir=.
      if test -f "$ac_dir/$ac_prog" || test -f "$ac_dir/$ac_prog$ac_exeext"; then
	LD="$ac_dir/$ac_prog"
	# Check to see if the program is GNU ld.  I'd rather use --version,
	# but apparently some GNU ld's only accept -v.
	# Break only if it was the GNU/non-GNU ld that we prefer.
	if "$LD" -v 2>&1 < /dev/null | egrep '(GNU|with BFD)' > /dev/null; then
	  test "$with_gnu_ld" != no && break
	else
	  test "$with_gnu_ld" != yes && break
	fi
      fi
    done
    IFS="$ac_save_ifs"
  fi

  if test -n "$LD"; then
    echo "$ac_t$LD" 1>&6
  else
    echo "$ac_t"no 1>&6
  fi

  if test -z "$LD"; then
    echo "$progname: error: no acceptable ld found in \$PATH" 1>&2
    exit 1
  fi
fi

# Check to see if it really is or is not GNU ld.
echo $ac_n "checking if the linker ($LD) is GNU ld... $ac_c" 1>&6
# I'd rather use --version here, but apparently some GNU ld's only accept -v.
if $LD -v 2>&1 </dev/null | egrep '(GNU|with BFD)' 1>&5; then
  with_gnu_ld=yes
else
  with_gnu_ld=no
fi
echo "$ac_t$with_gnu_ld" 1>&6

# See if the linker supports building shared libraries.
echo $ac_n "checking whether the linker ($LD) supports shared libraries... $ac_c" 1>&6

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=
export_dynamic_flag_spec=
whole_archive_flag_spec=
thread_safe_flag_spec=
hardcode_libdir_flag_spec=
hardcode_libdir_separator=
hardcode_direct=no
hardcode_minus_L=no
hardcode_shlibpath_var=unsupported
runpath_var=
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.

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

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*)
    # On AIX, the GNU linker is very broken
    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 $objdir/a2ixlibrary.data~$echo "#define NAME $libname" > $objdir/a2ixlibrary.data~$echo "#define LIBRARY_ID 1" >> $objdir/a2ixlibrary.data~$echo "#define VERSION $major" >> $objdir/a2ixlibrary.data~$echo "#define REVISION $revision" >> $objdir/a2ixlibrary.data~$AR cru $lib $libobjs~$RANLIB $lib~(cd $objdir && a2ixlibrary -32)'
    hardcode_libdir_flag_spec='-L$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 $linkopts ${wl}-soname $wl$soname -o $lib'
    else
      ld_shlibs=no
    fi
    ;;

  cygwin* | mingw*)
    # 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 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 by newer dlltools.
    export_symbols_cmds='test -f $objdir/$soname-ltdll.c || sed -e "/^# \/\* ltdll\.c starts here \*\//,/^# \/\* ltdll.c ends here \*\// { s/^# //; p; }" -e d < $0 > $objdir/$soname-ltdll.c~
      test -f $objdir/$soname-ltdll.$objext || (cd $objdir && $CC -c $soname-ltdll.c)~
      $DLLTOOL --export-all --exclude-symbols DllMain@12,_cygwin_dll_entry@12,_cygwin_noncygwin_dll_entry@12 --output-def $objdir/$soname-def  $objdir/$soname-ltdll.$objext $libobjs $convenience~
      sed -e "1,/EXPORTS/d" -e "s/ @ [0-9]*//" -e "s/ *;.*$//" < $objdir/$soname-def > $export_symbols'

    # If DATA tags from a recent dlltool are present, honour them!