configure

                cortex-m*)                 enable thumb; subarch=armv7m  ;;
                arm11*)                                  subarch=armv6   ;;
                arm[79]*e*|arm9[24]6*|arm96*|arm102[26]) subarch=armv5te ;;
                armv4*|arm7*|arm9[24]*)                  subarch=armv4   ;;
                *)                             subarch=$(probe_arm_arch) ;;
            esac
        ;;
    esac

    case "$subarch" in
        armv5t*)    enable fast_clz                ;;
        armv[6-8]*)
            enable fast_clz
            disabled fast_unaligned || enable fast_unaligned
            ;;
    esac

elif enabled avr32; then

    case $cpu in
        ap7[02]0[0-2])
            subarch="avr32_ap"
            cpuflags="-mpart=$cpu"
        ;;
        ap)
            subarch="avr32_ap"
            cpuflags="-march=$cpu"
        ;;
        uc3[ab]*)
            subarch="avr32_uc"
            cpuflags="-mcpu=$cpu"
        ;;
        uc)
            subarch="avr32_uc"
            cpuflags="-march=$cpu"
        ;;
    esac

elif enabled bfin; then

    cpuflags="-mcpu=$cpu"

elif enabled mips; then

    cpuflags="-march=$cpu"

    case $cpu in
        24kc)
            disable mips32r5
            disable mips64r6
            disable mipsfpu
            disable mipsdspr1
            disable mipsdspr2
            disable msa
        ;;
        24kf*)
            disable mips32r5
            disable mips64r6
            disable mipsdspr1
            disable mipsdspr2
            disable msa
        ;;
        24kec|34kc|1004kc)
            disable mips32r5
            disable mips64r6
            disable mipsfpu
            disable mipsdspr2
            disable msa
        ;;
        24kef*|34kf*|1004kf*)
            disable mips32r5
            disable mips64r6
            disable mipsdspr2
            disable msa
        ;;
        74kc)
            disable mips32r5
            disable mips64r6
            disable mipsfpu
            disable msa
        ;;
        74kf)
            disable mips32r5
            disable mips64r6
            disable msa
        ;;
        p5600)
            disable mips64r6
            disable mipsdspr1
            disable mipsdspr2

            check_cflags "-mtune=p5600"
        ;;
        i6400)
            disable mips32r5
            disable mipsdspr1
            disable mipsdspr2
            disable mipsfpu

            check_cflags "-mtune=i6400 -mabi=64"
            check_ldflags "-mabi=64"
        ;;
        loongson*)
            disable mipsfpu
            disable mips32r2
            disable mips32r5
            disable mips64r6
            disable mipsdspr1
            disable mipsdspr2
            disable msa
            enable local_aligned_8 local_aligned_16 local_aligned_32
            enable simd_align_16
            enable fast_64bit
            enable fast_clz
            enable fast_cmov
            enable fast_unaligned
            disable aligned_stack
            case $cpu in
                loongson3*)
                    cpuflags="-march=loongson3a -mhard-float -fno-expensive-optimizations"
                ;;
                loongson2e)
                    cpuflags="-march=loongson2e -mhard-float -fno-expensive-optimizations"
                ;;
                loongson2f)
                    cpuflags="-march=loongson2f -mhard-float -fno-expensive-optimizations"
                ;;
            esac
        ;;
        generic)
            disable mips32r5
            disable mips64r6
            disable msa
        ;;
        *)
            disable mipsfpu
            disable mips32r2
            disable mips32r5
            disable mips64r6
            disable mipsdspr1
            disable mipsdspr2
            disable msa
        ;;
    esac

elif enabled ppc; then

    disable ldbrx

    case $(tolower $cpu) in
        601|ppc601|powerpc601)
            cpuflags="-mcpu=601"
            disable altivec
        ;;
        603*|ppc603*|powerpc603*)
            cpuflags="-mcpu=603"
            disable altivec
        ;;
        604*|ppc604*|powerpc604*)
            cpuflags="-mcpu=604"
            disable altivec
        ;;
        g3|75*|ppc75*|powerpc75*)
            cpuflags="-mcpu=750"
            disable altivec
        ;;
        g4|745*|ppc745*|powerpc745*)
            cpuflags="-mcpu=7450"
            disable vsx
        ;;
        74*|ppc74*|powerpc74*)
            cpuflags="-mcpu=7400"
            disable vsx
        ;;
        g5|970|ppc970|powerpc970)
            cpuflags="-mcpu=970"
            disable vsx
        ;;
        power[3-6]*)
            cpuflags="-mcpu=$cpu"
            disable vsx
        ;;
        power[7-8]*)
            cpuflags="-mcpu=$cpu"
        ;;
        cell)
            cpuflags="-mcpu=cell"
            enable ldbrx
            disable vsx
        ;;
        e500mc)
            cpuflags="-mcpu=e500mc"
            disable altivec
        ;;
        e500v2)
            cpuflags="-mcpu=8548 -mhard-float -mfloat-gprs=double"
            disable altivec
            disable dcbzl
        ;;
        e500)
            cpuflags="-mcpu=8540 -mhard-float"
            disable altivec
            disable dcbzl
        ;;
    esac

elif enabled sparc; then

    case $cpu in
        cypress|f93[04]|tsc701|sparcl*|supersparc|hypersparc|niagara|v[789])
            cpuflags="-mcpu=$cpu"
        ;;
        ultrasparc*|niagara[234])
            cpuflags="-mcpu=$cpu"
        ;;
    esac

elif enabled x86; then

    case $cpu in
        i[345]86|pentium)
            cpuflags="-march=$cpu"
            disable i686
            disable mmx
        ;;
        # targets that do NOT support nopl and conditional mov (cmov)
        pentium-mmx|k6|k6-[23]|winchip-c6|winchip2|c3)
            cpuflags="-march=$cpu"
            disable i686
        ;;
        # targets that do support nopl and conditional mov (cmov)
        i686|pentiumpro|pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64*|k8*|opteron*|athlon-fx\
        |core*|atom|bonnell|nehalem|westmere|silvermont|sandybridge|ivybridge|haswell|broadwell|amdfam10|barcelona|b[dt]ver*)
            cpuflags="-march=$cpu"
            enable i686
            enable fast_cmov
        ;;
        # targets that do support conditional mov but on which it's slow
        pentium4|pentium4m|prescott|nocona)
            cpuflags="-march=$cpu"
            enable i686
            disable fast_cmov
        ;;
    esac

fi

if [ "$cpu" != generic ]; then
    add_cflags  $cpuflags
    add_asflags $cpuflags
    test "$cc_type" = "$ld_type" && add_ldflags $cpuflags
fi

# compiler sanity check
check_exec <<EOF
int main(void){ return 0; }
EOF
if test "$?" != 0; then
    echo "$cc is unable to create an executable file."
    if test -z "$cross_prefix" && ! enabled cross_compile ; then
        echo "If $cc is a cross-compiler, use the --enable-cross-compile option."
        echo "Only do this if you know what cross compiling means."
    fi
    die "C compiler test failed."
fi

add_cppflags -D_ISOC99_SOURCE
add_cxxflags -D__STDC_CONSTANT_MACROS
check_cflags -std=c99
check_cc -D_FILE_OFFSET_BITS=64 <<EOF && add_cppflags -D_FILE_OFFSET_BITS=64
#include <stdlib.h>
EOF
check_cc -D_LARGEFILE_SOURCE <<EOF && add_cppflags -D_LARGEFILE_SOURCE
#include <stdlib.h>
EOF

add_host_cppflags -D_ISOC99_SOURCE
check_host_cflags -std=c99
check_host_cflags -Wall
check_host_cflags -O3

check_64bit(){
    arch32=$1
    arch64=$2
    expr=$3
    check_code cc "" "int test[2*($expr) - 1]" &&
        subarch=$arch64 || subarch=$arch32
}

case "$arch" in
    aarch64|alpha|ia64)
        spic=$shared
    ;;
    mips)
        check_64bit mips mips64 '_MIPS_SIM > 1'
        spic=$shared
    ;;
    parisc)
        check_64bit parisc parisc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    ppc)
        check_64bit ppc ppc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    s390)
        check_64bit s390 s390x 'sizeof(void *) > 4'
        spic=$shared
    ;;
    sparc)
        check_64bit sparc sparc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    x86)
        check_64bit x86_32 x86_64 'sizeof(void *) > 4'
        # Treat x32 as x64 for now. Note it also needs spic=$shared
        test "$subarch" = "x86_32" && check_cpp_condition stddef.h 'defined(__x86_64__)' &&
            subarch=x86_64
        if test "$subarch" = "x86_64"; then
            spic=$shared
        fi
    ;;
    ppc)
        check_cc <<EOF && subarch="ppc64"
        int test[(int)sizeof(char*) - 7];
EOF
    ;;
esac

enable $subarch
enabled spic && enable_weak pic

# OS specific
case $target_os in
    aix)
        SHFLAGS=-shared
        add_cppflags '-I\$(SRC_PATH)/compat/aix'
        enabled shared && add_ldflags -Wl,-brtl
        ;;
    android)
        disable symver
        enable section_data_rel_ro
        SLIB_INSTALL_NAME='$(SLIBNAME)'
        SLIB_INSTALL_LINKS=
        # soname not set on purpose
        SHFLAGS=-shared
        ;;
    haiku)
        prefix_default="/boot/common"
        network_extralibs="-lnetwork"
        host_libs=
        ;;
    sunos)
        SHFLAGS='-shared -Wl,-h,$$(@F)'
        enabled x86 && SHFLAGS="-mimpure-text $SHFLAGS"
        network_extralibs="-lsocket -lnsl"
        add_cppflags -D__EXTENSIONS__
        # When using suncc to build, the Solaris linker will mark
        # an executable with each instruction set encountered by
        # the Solaris assembler.  As our libraries contain their own
        # guards for processor-specific code, instead suppress
        # generation of the HWCAPS ELF section on Solaris x86 only.
        enabled_all suncc x86 &&
            echo "hwcap_1 = OVERRIDE;" > mapfile &&
            add_ldflags -Wl,-M,mapfile
        nm_default='nm -P -g'
        SLIB_CREATE_DEF_CMD='$(Q)perl $(SRC_PATH)/compat/solaris/make_sunver.pl $$(filter %.ver,$$^) $(OBJS) | grep -v @ > $(SUBDIR)lib$(NAME).ver-sol2'
        ;;
    netbsd)
        disable symver
        oss_indev_extralibs="-lossaudio"
        oss_outdev_extralibs="-lossaudio"
        enabled gcc || check_ldflags -Wl,-zmuldefs
        ;;
    openbsd|bitrig)
        disable symver
        SHFLAGS='-shared'
        SLIB_INSTALL_NAME='$(SLIBNAME).$(LIBMAJOR).$(LIBMINOR)'
        SLIB_INSTALL_LINKS=
        oss_indev_extralibs="-lossaudio"
        oss_outdev_extralibs="-lossaudio"
        ;;
    dragonfly)
        disable symver
        ;;
    freebsd)
        ;;
    bsd/os)
        add_extralibs -lpoll -lgnugetopt
        strip="strip -d"
        ;;
    darwin)
        enabled ppc && add_asflags -force_cpusubtype_ALL
        SHFLAGS='-dynamiclib -Wl,-single_module -Wl,-install_name,$(SHLIBDIR)/$(SLIBNAME_WITH_MAJOR),-current_version,$(LIBVERSION),-compatibility_version,$(LIBMAJOR)'
        enabled x86_32 && append SHFLAGS -Wl,-read_only_relocs,suppress
        strip="${strip} -x"
        add_ldflags -Wl,-dynamic,-search_paths_first
        SLIBSUF=".dylib"
        SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME).$(LIBVERSION)$(SLIBSUF)'
        SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME).$(LIBMAJOR)$(SLIBSUF)'
        objformat="macho"
        enabled x86_64 && objformat="macho64"
        enabled_any pic shared x86_64 ||
            { check_cflags -mdynamic-no-pic && add_asflags -mdynamic-no-pic; }
        ;;
    mingw32*|mingw64*)
        if test $target_os = "mingw32ce"; then
            disable network
        else
            target_os=mingw32
        fi
        decklink_outdev_extralibs="$decklink_outdev_extralibs -lole32 -loleaut32"
        decklink_indev_extralibs="$decklink_indev_extralibs -lole32 -loleaut32"
        LIBTARGET=i386
        if enabled x86_64; then
            LIBTARGET="i386:x86-64"
        elif enabled arm; then
            LIBTARGET=arm-wince
        fi
        enabled shared && ! enabled small && check_cmd $windres --version && enable gnu_windres
        enabled x86_32 && check_ldflags -Wl,--large-address-aware
        shlibdir_default="$bindir_default"
        SLIBPREF=""
        SLIBSUF=".dll"
        SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
        SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
        dlltool="${cross_prefix}dlltool"
        if check_cmd lib.exe -list; then
            SLIB_EXTRA_CMD=-'sed -e "s/ @[^ ]*//" $$(@:$(SLIBSUF)=.orig.def) > $$(@:$(SLIBSUF)=.def); lib.exe /machine:$(LIBTARGET) /def:$$(@:$(SLIBSUF)=.def) /out:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
            if enabled x86_64; then
                LIBTARGET=x64
            fi
        elif check_cmd $dlltool --version; then
            SLIB_EXTRA_CMD=-'sed -e "s/ @[^ ]*//" $$(@:$(SLIBSUF)=.orig.def) > $$(@:$(SLIBSUF)=.def); $(DLLTOOL) -m $(LIBTARGET) -d $$(@:$(SLIBSUF)=.def) -l $(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib) -D $(SLIBNAME_WITH_MAJOR)'
        fi
        SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
        SLIB_INSTALL_LINKS=
        SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
        SLIB_INSTALL_EXTRA_LIB='lib$(SLIBNAME:$(SLIBSUF)=.dll.a) $(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
        SHFLAGS='-shared -Wl,--output-def,$$(@:$(SLIBSUF)=.orig.def) -Wl,--out-implib,$(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a) -Wl,--enable-runtime-pseudo-reloc -Wl,--disable-auto-image-base'
        objformat="win32"
        ranlib=:
        enable dos_paths
        check_ldflags -Wl,--nxcompat,--dynamicbase
        # Lets work around some stupidity in binutils.
        # ld will strip relocations from executables even though we need them
        # for dynamicbase (ASLR).  Using -pie does retain the reloc section
        # however ld then forgets what the entry point should be (oops) so we
        # have to manually (re)set it.
        if enabled x86_32; then
            add_ldexeflags -Wl,--pic-executable,-e,_mainCRTStartup
        elif enabled x86_64; then
            add_ldexeflags -Wl,--pic-executable,-e,mainCRTStartup
            check_ldflags -Wl,--high-entropy-va # binutils 2.25
            # Set image base >4GB for extra entropy with HEASLR
            add_ldexeflags -Wl,--image-base,0x140000000
            append SHFLAGS -Wl,--image-base,0x180000000
        fi
        ;;
    win32|win64)
        disable symver
        if enabled shared; then
            # Link to the import library instead of the normal static library
            # for shared libs.
            LD_LIB='%.lib'
            # Cannot build both shared and static libs with MSVC or icl.
            disable static
        fi
        enabled x86_32 && check_ldflags -LARGEADDRESSAWARE
        shlibdir_default="$bindir_default"
        SLIBPREF=""
        SLIBSUF=".dll"
        SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
        SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
        SLIB_CREATE_DEF_CMD='$(SRC_PATH)/compat/windows/makedef $(SUBDIR)lib$(NAME).ver $(OBJS) > $$(@:$(SLIBSUF)=.def)'
        SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
        SLIB_INSTALL_LINKS=
        SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
        SLIB_INSTALL_EXTRA_LIB='$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
        SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
        objformat="win32"
        ranlib=:
        enable dos_paths
        ;;
    cygwin*)
        target_os=cygwin
        shlibdir_default="$bindir_default"
        SLIBPREF="cyg"
        SLIBSUF=".dll"
        SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
        SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
        SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
        SLIB_INSTALL_LINKS=
        SLIB_INSTALL_EXTRA_LIB='lib$(FULLNAME).dll.a'
        SHFLAGS='-shared -Wl,--out-implib,$(SUBDIR)lib$(FULLNAME).dll.a'
        objformat="win32"
        enable dos_paths
        enabled shared && ! enabled small && check_cmd $windres --version && enable gnu_windres
        ;;
    *-dos|freedos|opendos)
        network_extralibs="-lsocket"
        objformat="coff"
        enable dos_paths
        add_cppflags -U__STRICT_ANSI__
        ;;
    linux)
        enable dv1394
        enable section_data_rel_ro
        ;;
    irix*)
        target_os=irix
        ranlib="echo ignoring ranlib"
        ;;
    os/2*)
        strip="lxlite -CS"
        ln_s="cp -f"
        objformat="aout"
        add_cppflags -D_GNU_SOURCE
        add_ldflags -Zomf -Zbin-files -Zargs-wild -Zmap
        SHFLAGS='$(SUBDIR)$(NAME).def -Zdll -Zomf'
        LIBSUF="_s.a"
        SLIBPREF=""
        SLIBSUF=".dll"
        SLIBNAME_WITH_VERSION='$(SLIBPREF)$(NAME)-$(LIBVERSION)$(SLIBSUF)'
        SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(shell echo $(NAME) | cut -c1-6)$(LIBMAJOR)$(SLIBSUF)'
        SLIB_CREATE_DEF_CMD='echo LIBRARY $(SLIBNAME_WITH_MAJOR) INITINSTANCE TERMINSTANCE > $(SUBDIR)$(NAME).def; \
            echo CODE PRELOAD MOVEABLE DISCARDABLE >> $(SUBDIR)$(NAME).def; \
            echo DATA PRELOAD MOVEABLE MULTIPLE NONSHARED >> $(SUBDIR)$(NAME).def; \
            echo EXPORTS >> $(SUBDIR)$(NAME).def; \
            emxexp $(OBJS) >> $(SUBDIR)$(NAME).def'
        SLIB_EXTRA_CMD='emximp -o $(SUBDIR)$(LIBPREF)$(NAME)_dll.a $(SUBDIR)$(NAME).def; \
            emximp -o $(SUBDIR)$(LIBPREF)$(NAME)_dll.lib $(SUBDIR)$(NAME).def;'
        SLIB_INSTALL_EXTRA_LIB='$(LIBPREF)$(NAME)_dll.a $(LIBPREF)$(NAME)_dll.lib'
        enable dos_paths
        enable_weak os2threads
        ;;
    gnu/kfreebsd)
        add_cppflags -D_BSD_SOURCE
        ;;
    gnu)
        ;;
    qnx)
        add_cppflags -D_QNX_SOURCE
        network_extralibs="-lsocket"
        ;;
    symbian)
        SLIBSUF=".dll"
        enable dos_paths
        add_cflags --include=$sysinclude/gcce/gcce.h -fvisibility=default
        add_cppflags -D__GCCE__ -D__SYMBIAN32__ -DSYMBIAN_OE_POSIX_SIGNALS
        add_ldflags -Wl,--target1-abs,--no-undefined \
                    -Wl,-Ttext,0x80000,-Tdata,0x1000000 -shared \
                    -Wl,--entry=_E32Startup -Wl,-u,_E32Startup
        add_extralibs -l:eexe.lib -l:usrt2_2.lib -l:dfpaeabi.dso \
                      -l:drtaeabi.dso -l:scppnwdl.dso -lsupc++ -lgcc \
                      -l:libc.dso -l:libm.dso -l:euser.dso -l:libcrt0.lib
        ;;
    osf1)
        add_cppflags -D_OSF_SOURCE -D_POSIX_PII -D_REENTRANT
        ;;
    minix)
        ;;
    plan9)
        add_cppflags -D_C99_SNPRINTF_EXTENSION  \
                     -D_REENTRANT_SOURCE        \
                     -D_RESEARCH_SOURCE         \
                     -DFD_SETSIZE=96            \
                     -DHAVE_SOCK_OPTS
        add_compat strtod.o strtod=avpriv_strtod
        network_extralibs='-lbsd'
        exeobjs=compat/plan9/main.o
        disable ffserver
        cp_f='cp'
        ;;
    none)
        ;;
    *)
        die "Unknown OS '$target_os'."
        ;;
esac

# determine libc flavour

probe_libc(){
    pfx=$1
    pfx_no_=${pfx%_}
    # uclibc defines __GLIBC__, so it needs to be checked before glibc.
    if check_${pfx}cpp_condition features.h "defined __UCLIBC__"; then
        eval ${pfx}libc_type=uclibc
        add_${pfx}cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
    elif check_${pfx}cpp_condition features.h "defined __GLIBC__"; then
        eval ${pfx}libc_type=glibc
        add_${pfx}cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
    # MinGW headers can be installed on Cygwin, so check for newlib first.
    elif check_${pfx}cpp_condition newlib.h "defined _NEWLIB_VERSION"; then
        eval ${pfx}libc_type=newlib
        add_${pfx}cppflags -U__STRICT_ANSI__
    # MinGW64 is backwards compatible with MinGW32, so check for it first.
    elif check_${pfx}cpp_condition _mingw.h "defined __MINGW64_VERSION_MAJOR"; then
        eval ${pfx}libc_type=mingw64
        if check_${pfx}cpp_condition _mingw.h "__MINGW64_VERSION_MAJOR < 3"; then
            add_compat msvcrt/snprintf.o
            add_cflags "-include $source_path/compat/msvcrt/snprintf.h"
        fi
        add_${pfx}cppflags -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1
        eval test \$${pfx_no_}cc_type = "gcc" &&
            add_${pfx}cppflags -D__printf__=__gnu_printf__
    elif check_${pfx}cpp_condition _mingw.h "defined __MINGW_VERSION"  ||
         check_${pfx}cpp_condition _mingw.h "defined __MINGW32_VERSION"; then
        eval ${pfx}libc_type=mingw32
        check_${pfx}cpp_condition _mingw.h "__MINGW32_MAJOR_VERSION > 3 || \
            (__MINGW32_MAJOR_VERSION == 3 && __MINGW32_MINOR_VERSION >= 15)" ||
            die "ERROR: MinGW32 runtime version must be >= 3.15."
        add_${pfx}cppflags -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1
        eval test \$${pfx_no_}cc_type = "gcc" &&
            add_${pfx}cppflags -D__printf__=__gnu_printf__
    elif check_${pfx}cpp_condition crtversion.h "defined _VC_CRT_MAJOR_VERSION"; then
        eval ${pfx}libc_type=msvcrt
        if check_${pfx}cpp_condition crtversion.h "_VC_CRT_MAJOR_VERSION < 14"; then
            if [ "$pfx" = host_ ]; then
                add_host_cppflags -Dsnprintf=_snprintf
            else
                add_compat strtod.o strtod=avpriv_strtod
                add_compat msvcrt/snprintf.o snprintf=avpriv_snprintf   \
                                             _snprintf=avpriv_snprintf  \
                                             vsnprintf=avpriv_vsnprintf
            fi
        fi
        # The MSVC 2010 headers (Win 7.0 SDK) set _WIN32_WINNT to
        # 0x601 by default unless something else is set by the user.
        # This can easily lead to us detecting functions only present
        # in such new versions and producing binaries requiring windows 7.0.
        # Therefore explicitly set the default to XP unless the user has
        # set something else on the command line.
        # Don't do this if WINAPI_FAMILY is set and is set to a non-desktop
        # family. For these cases, configure is free to use any functions
        # found in the SDK headers by default. (Alternatively, we could force
        # _WIN32_WINNT to 0x0602 in that case.)
        check_${pfx}cpp_condition stdlib.h "defined(_WIN32_WINNT)" ||
            { check_${pfx}cpp <<EOF && add_${pfx}cppflags -D_WIN32_WINNT=0x0502; }
#ifdef WINAPI_FAMILY
#include <winapifamily.h>
#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
#error not desktop
#endif
#endif
EOF
    elif check_${pfx}cpp_condition stddef.h "defined __KLIBC__"; then
        eval ${pfx}libc_type=klibc
    elif check_${pfx}cpp_condition sys/cdefs.h "defined __BIONIC__"; then
        eval ${pfx}libc_type=bionic
    elif check_${pfx}cpp_condition sys/brand.h "defined LABELED_BRAND_NAME"; then
        eval ${pfx}libc_type=solaris
        add_${pfx}cppflags -D__EXTENSIONS__ -D_XOPEN_SOURCE=600
    fi
    check_${pfx}cc <<EOF
#include <time.h>
void *v = localtime_r;
EOF
test "$?" != 0 && check_${pfx}cc -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 <<EOF && add_${pfx}cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
#include <time.h>
void *v = localtime_r;
EOF

}

probe_libc
test -n "$libc_type" && enable libc_$libc_type
probe_libc host_
test -n "$host_libc_type" && enable host_libc_$host_libc_type

case $libc_type in
    bionic)
        add_compat strtod.o strtod=avpriv_strtod
        ;;
esac

# hacks for compiler/libc/os combinations

if enabled_all tms470 libc_glibc; then
    CPPFLAGS="-I${source_path}/compat/tms470 ${CPPFLAGS}"
    add_cppflags -D__USER_LABEL_PREFIX__=
    add_cppflags -D__builtin_memset=memset
    add_cppflags -D__gnuc_va_list=va_list -D_VA_LIST_DEFINED
    add_cflags   -pds=48    # incompatible redefinition of macro
fi

if enabled_all ccc libc_glibc; then
    add_ldflags -Wl,-z,now  # calls to libots crash without this
fi

check_compile_assert flt_lim "float.h limits.h" "DBL_MAX == (double)DBL_MAX" ||
    add_cppflags '-I\$(SRC_PATH)/compat/float'

esc(){
    echo "$*" | sed 's/%/%25/g;s/:/%3a/g'
}

echo "config:$arch:$subarch:$cpu:$target_os:$(esc $cc_ident):$(esc $FFMPEG_CONFIGURATION)" >config.fate

check_cpp_condition stdlib.h "defined(__PIC__) || defined(__pic__) || defined(PIC)" && enable_weak pic

set_default libdir
: ${shlibdir_default:="$libdir"}
: ${pkgconfigdir_default:="$libdir/pkgconfig"}

set_default $PATHS_LIST
set_default nm

# we need to build at least one lib type
if ! enabled_any static shared; then
    cat <<EOF
At least one library type must be built.
Specify --enable-static to build the static libraries or --enable-shared to
build the shared libraries as well. To only build the shared libraries specify
--disable-static in addition to --enable-shared.
EOF
    exit 1;
fi

die_license_disabled() {
    enabled $1 || { enabled $2 && die "$2 is $1 and --enable-$1 is not specified."; }
}

die_license_disabled_gpl() {
    enabled $1 || { enabled $2 && die "$2 is incompatible with the gpl and --enable-$1 is not specified."; }
}

die_license_disabled gpl frei0r
die_license_disabled gpl libcdio
die_license_disabled gpl librubberband
die_license_disabled gpl libsmbclient
die_license_disabled gpl libutvideo
die_license_disabled gpl libvidstab
die_license_disabled gpl libx264
die_license_disabled gpl libx265
die_license_disabled gpl libxavs
die_license_disabled gpl libxvid
die_license_disabled gpl libzvbi
die_license_disabled gpl x11grab

die_license_disabled nonfree libaacplus
die_license_disabled nonfree libfaac
die_license_disabled nonfree nvenc
enabled gpl && die_license_disabled_gpl nonfree libfdk_aac
enabled gpl && die_license_disabled_gpl nonfree openssl

die_license_disabled version3 libopencore_amrnb
die_license_disabled version3 libopencore_amrwb
die_license_disabled version3 libsmbclient
die_license_disabled version3 libvo_aacenc
die_license_disabled version3 libvo_amrwbenc

enabled version3 && { enabled gpl && enable gplv3 || enable lgplv3; }

disabled optimizations || check_cflags -fomit-frame-pointer

enable_weak_pic() {
    disabled pic && return
    enable pic
    add_cppflags -DPIC
    case "$target_os" in
    mingw*|cygwin*)
        ;;
    *)
        add_cflags -fPIC
        ;;
    esac
    add_asflags  -fPIC
}

enabled pic && enable_weak_pic

check_cc <<EOF || die "Symbol mangling check failed."
int ff_extern;
EOF
sym=$($nm $TMPO | awk '/ff_extern/{ print substr($0, match($0, /[^ \t]*ff_extern/)) }')
extern_prefix=${sym%%ff_extern*}

check_cc <<EOF && enable_weak inline_asm
void foo(void) { __asm__ volatile ("" ::); }
EOF

_restrict=
for restrict_keyword in restrict __restrict__ __restrict; do
    check_cc <<EOF && _restrict=$restrict_keyword && break
void foo(char * $restrict_keyword p);
EOF
done

check_cc <<EOF && enable pragma_deprecated
void foo(void) { _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") }
EOF

check_cc <<EOF && enable attribute_packed
struct { int x; } __attribute__((packed)) x;
EOF

check_cc <<EOF && enable attribute_may_alias
union { int x; } __attribute__((may_alias)) x;
EOF

check_cc <<EOF || die "endian test failed"
unsigned int endian = 'B' << 24 | 'I' << 16 | 'G' << 8 | 'E';
EOF
od -t x1 $TMPO | grep -q '42 *49 *47 *45' && enable bigendian

if ! enabled ppc64 || enabled bigendian; then
    disable vsx
fi

check_gas() {
    log "check_gas using '$as' as AS"
    # :vararg is used on aarch64, arm and ppc altivec
    check_as <<EOF || return 1
.macro m n, y:vararg=0
\n: .int \y
.endm
m x
EOF
    # .altmacro is only used in arm asm
    ! enabled arm || check_as <<EOF || return 1
.altmacro
EOF
    enable gnu_as
    return 0
}

if enabled_any arm aarch64 || enabled_all ppc altivec && enabled asm; then
    nogas=:
    enabled_any arm aarch64 && nogas=die
    enabled_all ppc altivec && [ $target_os_default != aix ] && nogas=warn
    as_noop=-v

    case $as_type in
        arm*) gaspp_as_type=armasm; as_noop=-h ;;
        gcc)  gaspp_as_type=gas ;;
        *)    gaspp_as_type=$as_type ;;
    esac

    [ $target_os = "darwin" ] && gaspp_as_type="apple-$gaspp_as_type"

    test "${as#*gas-preprocessor.pl}" != "$as" ||
    check_cmd gas-preprocessor.pl -arch $arch -as-type $gaspp_as_type -- ${as:=$cc} $as_noop &&
        gas="${gas:=gas-preprocessor.pl} -arch $arch -as-type $gaspp_as_type -- ${as:=$cc}"

    if ! check_gas ; then
        as=${gas:=$as}
        check_gas || \
            $nogas "GNU assembler not found, install/update gas-preprocessor"
    fi

    check_as <<EOF && enable as_func
.func test
.endfunc
EOF
fi

check_inline_asm inline_asm_labels '"1:\n"'

check_inline_asm inline_asm_nonlocal_labels '"Label:\n"'

if enabled aarch64; then
    enabled armv8 && check_insn armv8 'prfm   pldl1strm, [x0]'
    # internal assembler in clang 3.3 does not support this instruction
    enabled neon && check_insn neon 'ext   v0.8B, v0.8B, v1.8B, #1'
    enabled vfp  && check_insn vfp  'fmadd d0,    d0,    d1,    d2'

    map 'enabled_any ${v}_external ${v}_inline || disable $v' $ARCH_EXT_LIST_ARM

elif enabled alpha; then

    check_cflags -mieee

elif enabled arm; then

    enabled msvc && check_cpp_condition stddef.h "defined _M_ARMT" && enable thumb

    check_cpp_condition stddef.h "defined __thumb__" && check_cc <<EOF && enable_weak thumb
float func(float a, float b){ return a+b; }
EOF

    enabled thumb && check_cflags -mthumb || check_cflags -marm

    if     check_cpp_condition stddef.h "defined __ARM_PCS_VFP"; then
        enable vfp_args
    elif check_cpp_condition stddef.h "defined _M_ARM_FP && _M_ARM_FP >= 30"; then
        enable vfp_args
    elif ! check_cpp_condition stddef.h "defined __ARM_PCS || defined __SOFTFP__" && [ $target_os != darwin ]; then
        case "${cross_prefix:-$cc}" in
            *hardfloat*)         enable vfp_args;   fpabi=vfp ;;
            *) check_ld "cc" <<EOF && enable vfp_args && fpabi=vfp || fpabi=soft ;;
__asm__ (".eabi_attribute 28, 1");
int main(void) { return 0; }
EOF
        esac
        warn "Compiler does not indicate floating-point ABI, guessing $fpabi."
    fi

    enabled armv5te && check_insn armv5te 'qadd r0, r0, r0'
    enabled armv6   && check_insn armv6   'sadd16 r0, r0, r0'
    enabled armv6t2 && check_insn armv6t2 'movt r0, #0'
    enabled neon    && check_insn neon    'vadd.i16 q0, q0, q0'
    enabled vfp     && check_insn vfp     'fadds s0, s0, s0'
    enabled vfpv3   && check_insn vfpv3   'vmov.f32 s0, #1.0'
    enabled setend  && check_insn setend  'setend be'

    [ $target_os = linux ] || [ $target_os = android ] ||
        map 'enabled_any ${v}_external ${v}_inline || disable $v' \
            $ARCH_EXT_LIST_ARM

    check_inline_asm asm_mod_q '"add r0, %Q0, %R0" :: "r"((long long)0)'

    check_as <<EOF && enable as_dn_directive
ra .dn d0.i16
.unreq ra
EOF

    # llvm's integrated assembler supports .object_arch from llvm 3.5
    [ "$objformat" = elf ] && check_as <<EOF && enable as_object_arch
.object_arch armv4
EOF

    [ $target_os != win32 ] && enabled_all armv6t2 shared !pic && enable_weak_pic

elif enabled mips; then

    enabled loongson2 && check_inline_asm loongson2 '"dmult.g $8, $9, $10"'
    enabled loongson3 && check_inline_asm loongson3 '"gsldxc1 $f0, 0($2, $3)"'
    enabled mmi && check_inline_asm mmi '"punpcklhw $f0, $f0, $f0"'

    # Enable minimum ISA based on selected options
    if enabled mips64 && (enabled mipsdspr1 || enabled mipsdspr2); then
        add_cflags "-mips64r2"
        add_asflags "-mips64r2"
    elif enabled mips64 && enabled mipsfpu && disabled loongson2 && disabled loongson3; then
        add_cflags "-mips64"
        add_asflags "-mips64"
    elif enabled mipsdspr1 || enabled mipsdspr2; then
        add_cflags "-mips32r2 -mfp32"
        add_asflags "-mips32r2 -mfp32"
    elif enabled mips32r5 || enabled mips64r6; then
        check_cflags "-mfp64"
        check_ldflags "-mfp64"
    fi

    enabled mips32r5  && check_cflags "-mips32r5 -msched-weight -mload-store-pairs -funroll-loops" &&
     check_ldflags "-mips32r5" &&
     check_inline_asm mips32r5  '"ulw $t0, ($t1)"'
    enabled mips64r6  && check_cflags "-mips64r6 -msched-weight -mload-store-pairs -funroll-loops" &&
     check_ldflags "-mips64r6" &&
     check_inline_asm mips64r6  '"aui $t0, $t1, 1"'
    enabled mipsdspr1 && add_cflags "-mdsp" && add_asflags "-mdsp" &&
     check_inline_asm mipsdspr1 '"addu.qb $t0, $t1, $t2"'
    enabled mipsdspr2 && add_cflags "-mdspr2" && add_asflags "-mdspr2" &&
     check_inline_asm mipsdspr2 '"absq_s.qb $t0, $t1"'
    enabled mipsfpu   && add_cflags "-mhard-float" && add_asflags "-mhard-float" &&
     check_inline_asm mipsfpu   '"madd.d $f0, $f2, $f4, $f6"'
    enabled msa       && check_cflags "-mmsa" && check_ldflags "-mmsa" &&
     check_inline_asm msa       '"addvi.b $w0, $w1, 1"'

    enabled mips32r5 && add_asflags "-mips32r5 -mfp64"
    enabled mips64r6 && add_asflags "-mips64r6 -mfp64"
    enabled msa && add_asflags "-mmsa"

elif enabled parisc; then

    if enabled gcc; then
        case $($cc -dumpversion) in
            4.[3-9].*) check_cflags -fno-optimize-sibling-calls ;;
        esac
    fi

elif enabled ppc; then

    enable local_aligned_8 local_aligned_16 local_aligned_32

    check_inline_asm dcbzl     '"dcbzl 0, %0" :: "r"(0)'
    check_inline_asm ibm_asm   '"add 0, 0, 0"'
    check_inline_asm ppc4xx    '"maclhw r10, r11, r12"'
    check_inline_asm xform_asm '"lwzx %1, %y0" :: "Z"(*(int*)0), "r"(0)'

    # AltiVec flags: The FSF version of GCC differs from the Apple version
    if enabled altivec; then
        check_cflags -maltivec -mabi=altivec &&
        { check_header altivec.h && inc_altivec_h="#include <altivec.h>" ; } ||
        check_cflags -faltivec

        # check if our compiler supports Motorola AltiVec C API
        check_cc <<EOF || disable altivec
$inc_altivec_h
int main(void) {
    vector signed int v1 = (vector signed int) { 0 };
    vector signed int v2 = (vector signed int) { 1 };
    v1 = vec_add(v1, v2);
    return 0;
}
EOF

        enabled altivec || warn "Altivec disabled, possibly missing --cpu flag"