configure

    [ -e src ] && rm src
    $ln_s "$source_path" src
    source_link=src
else
    # creating directory links doesn't work
    # fall back to using the full source path
    source_link="$source_path"
fi
# cleanup
rm -r "$link_dest"
rm -r "$link_name"

# 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_${pfx}cppflags -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1
        check_${pfx}cpp_condition _mingw.h "defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0502" ||
            add_${pfx}cppflags -D_WIN32_WINNT=0x0502
        check_${pfx}cpp_condition _mingw.h "__MSVCRT_VERSION__ < 0x0700__" &&
            add_${pfx}cppflags -D__MSVCRT_VERSION__=0x0700
        eval test \$${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 [ "$pfx" = host_ ]; then
                add_host_cppflags -Dsnprintf=_snprintf
            else
                add_compat strtod.o strtod=avpriv_strtod
                add_compat msvcrt/snprintf.o snprintf=avpriv_snprintf   \
                                             _snprintf=avpriv_snprintf  \
                                             vsnprintf=avpriv_vsnprintf
            fi
        fi
        add_${pfx}cppflags -D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_WARNINGS
        # 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_${pfx}cppflags -D_WIN32_WINNT=0x0502; }
#ifdef WINAPI_FAMILY
#include <winapifamily.h>
#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
#error not desktop
#endif
#endif
EOF
        if [ "$pfx" = "" ]; then
            check_func strtoll || add_cflags -Dstrtoll=_strtoi64
            check_func strtoull || add_cflags -Dstrtoull=_strtoui64
        fi
    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 $v && die "$v is $1 and --enable-$1 is not specified."; }
}

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

map "die_license_disabled gpl"      $EXTERNAL_LIBRARY_GPL_LIST $EXTERNAL_LIBRARY_GPLV3_LIST
map "die_license_disabled version3" $EXTERNAL_LIBRARY_VERSION3_LIST $EXTERNAL_LIBRARY_GPLV3_LIST

enabled gpl && map "die_license_disabled_gpl nonfree" $EXTERNAL_LIBRARY_NONFREE_LIST
map "die_license_disabled nonfree" $HWACCEL_LIBRARY_NONFREE_LIST

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
    check_as <<EOF && enable as_fpu_directive
.fpu neon
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; then
        enabled mips64r6 && check_inline_asm_flags mips64r6 '"dlsa $0, $0, $0, 1"' '-mips64r6'
        enabled mips64r2 && check_inline_asm_flags mips64r2 '"dext $0, $0, 0, 1"' '-mips64r2'
        disabled mips64r6 && disabled mips64r2 && check_inline_asm_flags mips64r1 '"daddi $0, $0, 0"' '-mips64'
    else
        enabled mips32r6 && check_inline_asm_flags mips32r6 '"aui $0, $0, 0"' '-mips32r6'
        enabled mips32r5 && check_inline_asm_flags mips32r5 '"eretnc"' '-mips32r5'
        enabled mips32r2 && check_inline_asm_flags mips32r2 '"ext $0, $0, 0, 1"' '-mips32r2'
        disabled mips32r6 && disabled mips32r5 && disabled mips32r2 && check_inline_asm_flags mips32r1 '"addi $0, $0, 0"' '-mips32'
    fi

    enabled mipsfpu && check_inline_asm_flags mipsfpu '"cvt.d.l $f0, $f2"' '-mhard-float'
    enabled mipsfpu && (enabled mips32r5 || enabled mips32r6 || enabled mips64r6) && check_inline_asm_flags mipsfpu '"cvt.d.l $f0, $f1"' '-mfp64'
    enabled mipsfpu && enabled msa && check_inline_asm_flags msa '"addvi.b $w0, $w1, 1"' '-mmsa' && check_header msa.h || disable msa
    enabled mipsdsp && check_inline_asm_flags mipsdsp '"addu.qb $t0, $t1, $t2"' '-mdsp'
    enabled mipsdspr2 && check_inline_asm_flags mipsdspr2 '"absq_s.qb $t0, $t1"' '-mdspr2'

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"
    fi

    if enabled vsx; then
        check_cflags -mvsx &&
        check_builtin vec_vsx_ld "altivec.h" "__builtin_vec_vsx_ld" || disable vsx
    fi

    if enabled power8; then
        check_cpp_condition "altivec.h" "defined(_ARCH_PWR8)" || disable power8
    fi

elif enabled x86; then

    check_builtin rdtsc    intrin.h   "__rdtsc()"
    check_builtin mm_empty mmintrin.h "_mm_empty()"

    enable local_aligned_8 local_aligned_16 local_aligned_32

    # check whether EBP is available on x86
    # As 'i' is stored on the stack, this program will crash
    # if the base pointer is used to access it because the
    # base pointer is cleared in the inline assembly code.
    check_exec_crash <<EOF && enable ebp_available
volatile int i=0;
__asm__ volatile ("xorl %%ebp, %%ebp" ::: "%ebp");
return i;
EOF

    # check whether EBX is available on x86
    check_inline_asm ebx_available '""::"b"(0)' &&
        check_inline_asm ebx_available '"":::"%ebx"'

    # check whether xmm clobbers are supported
    check_inline_asm xmm_clobbers '"":::"%xmm0"'

    check_inline_asm inline_asm_direct_symbol_refs '"movl '$extern_prefix'test, %eax"' ||
        check_inline_asm inline_asm_direct_symbol_refs '"movl '$extern_prefix'test(%rip), %eax"'

    # check whether binutils is new enough to compile SSSE3/MMXEXT
    enabled ssse3  && check_inline_asm ssse3_inline  '"pabsw %xmm0, %xmm0"'
    enabled mmxext && check_inline_asm mmxext_inline '"pmaxub %mm0, %mm1"'

    if ! disabled_any asm mmx yasm; then
        if check_cmd $yasmexe --version; then
            enabled x86_64 && yasm_extra="-m amd64"
            yasm_debug="-g dwarf2"
        elif check_cmd nasm -v; then
            yasmexe=nasm
            yasm_debug="-g -F dwarf"
            if enabled x86_64; then
                case "$objformat" in
                    elf)   objformat=elf64 ;;
                    win32) objformat=win64 ;;
                esac
            fi
        fi

        YASMFLAGS="-f $objformat $yasm_extra"
        enabled pic               && append YASMFLAGS "-DPIC"
        test -n "$extern_prefix"  && append YASMFLAGS "-DPREFIX"
        case "$objformat" in
            elf*) enabled debug && append YASMFLAGS $yasm_debug ;;
        esac

        check_yasm "movbe ecx, [5]" && enable yasm ||
            die "yasm/nasm not found or too old. Use --disable-yasm for a crippled build."
        check_yasm "vextracti128 xmm0, ymm0, 0"      || disable avx2_external
        check_yasm "vpmacsdd xmm0, xmm1, xmm2, xmm3" || disable xop_external
        check_yasm "vfmaddps ymm0, ymm1, ymm2, ymm3" || disable fma4_external
        check_yasm "CPU amdnop" || disable cpunop
    fi

    case "$cpu" in
        athlon*|opteron*|k8*|pentium|pentium-mmx|prescott|nocona|atom|geode)
            disable fast_clz
        ;;
    esac

fi

check_code cc arm_neon.h "int16x8_t test = vdupq_n_s16(0)" && enable intrinsics_neon

check_ldflags -Wl,--as-needed
check_ldflags -Wl,-z,noexecstack

if check_func dlopen && check_func dlsym; then
    ldl=
elif check_func dlopen -ldl && check_func dlsym -ldl; then
    ldl=-ldl
fi

avisynth_demuxer_extralibs='$ldl'
cuda_extralibs='$ldl'
decklink_outdev_extralibs="$decklink_outdev_extralibs $ldl"
decklink_indev_extralibs="$decklink_indev_extralibs $ldl"
frei0r_filter_extralibs='$ldl'
frei0r_src_filter_extralibs='$ldl'
ladspa_filter_extralibs='$ldl'
nvenc_extralibs='$ldl'
coreimage_filter_extralibs="-framework QuartzCore -framework AppKit -framework OpenGL"
coreimagesrc_filter_extralibs="-framework QuartzCore -framework AppKit -framework OpenGL"

if ! disabled network; then
    check_func getaddrinfo $network_extralibs
    check_func inet_aton $network_extralibs

    check_type netdb.h "struct addrinfo"
    check_type netinet/in.h "struct group_source_req" -D_BSD_SOURCE
    check_type netinet/in.h "struct ip_mreq_source" -D_BSD_SOURCE
    check_type netinet/in.h "struct ipv6_mreq" -D_DARWIN_C_SOURCE
    check_type poll.h "struct pollfd"
    check_type netinet/sctp.h "struct sctp_event_subscribe"
    check_struct "sys/socket.h" "struct msghdr" msg_flags
    check_struct "sys/types.h sys/socket.h" "struct sockaddr" sa_len
    check_type netinet/in.h "struct sockaddr_in6"
    check_type "sys/types.h sys/socket.h" "struct sockaddr_storage"
    check_type "sys/types.h sys/socket.h" socklen_t

    # Prefer arpa/inet.h over winsock2
    if check_header arpa/inet.h ; then
        check_func closesocket
    elif check_header winsock2.h ; then
        check_func_headers winsock2.h closesocket -lws2 &&
            network_extralibs="-lws2" ||
        { check_func_headers winsock2.h closesocket -lws2_32 &&
            network_extralibs="-lws2_32"; } || disable winsock2_h network
        check_func_headers ws2tcpip.h getaddrinfo $network_extralibs

        check_type ws2tcpip.h socklen_t
        check_type ws2tcpip.h "struct addrinfo"
        check_type ws2tcpip.h "struct group_source_req"
        check_type ws2tcpip.h "struct ip_mreq_source"
        check_type ws2tcpip.h "struct ipv6_mreq"
        check_type winsock2.h "struct pollfd"
        check_struct winsock2.h "struct sockaddr" sa_len
        check_type ws2tcpip.h "struct sockaddr_in6"
        check_type ws2tcpip.h "struct sockaddr_storage"
    else
        disable network
    fi
fi

check_builtin atomic_cas_ptr atomic.h "void **ptr; void *oldval, *newval; atomic_cas_ptr(ptr, oldval, newval)"
check_builtin machine_rw_barrier mbarrier.h "__machine_rw_barrier()"
check_builtin MemoryBarrier windows.h "MemoryBarrier()"
check_builtin sarestart signal.h "SA_RESTART"
check_builtin sem_timedwait semaphore.h "sem_t *s; sem_init(s,0,0); sem_timedwait(s,0); sem_destroy(s)" -lpthread
check_builtin sync_val_compare_and_swap "" "int *ptr; int oldval, newval; __sync_val_compare_and_swap(ptr, oldval, newval)"
check_builtin gmtime_r time.h "time_t *time; struct tm *tm; gmtime_r(time, tm)"
check_builtin localtime_r time.h "time_t *time; struct tm *tm; localtime_r(time, tm)"
check_builtin x264_csp_bgr "stdint.h x264.h" "X264_CSP_BGR"

case "$custom_allocator" in
    jemalloc)
        # jemalloc by default does not use a prefix
        require libjemalloc jemalloc/jemalloc.h malloc -ljemalloc
    ;;
    tcmalloc)
        require_pkg_config libtcmalloc gperftools/tcmalloc.h tc_malloc
        malloc_prefix=tc_
    ;;
esac

check_func_headers malloc.h _aligned_malloc     && enable aligned_malloc
check_func  ${malloc_prefix}memalign            && enable memalign
check_func  ${malloc_prefix}posix_memalign      && enable posix_memalign

check_func  access
check_func_headers stdlib.h arc4random
check_func_headers time.h clock_gettime ||
    { check_lib time.h clock_gettime -lrt && LIBRT="-lrt"; }
check_func  fcntl
check_func  fork
check_func  gethrtime
check_func  getopt
check_func  getrusage
check_func  gettimeofday
check_func  isatty
check_func  mach_absolute_time
check_func  mkstemp
check_func  mmap
check_func  mprotect
# Solaris has nanosleep in -lrt, OpenSolaris no longer needs that
check_func_headers time.h nanosleep ||
    { check_lib time.h nanosleep -lrt && LIBRT="-lrt"; }
check_func  sched_getaffinity
check_func  setrlimit
check_struct "sys/stat.h" "struct stat" st_mtim.tv_nsec -D_BSD_SOURCE
check_func  strerror_r
check_func  sysconf
check_func  sysctl
check_func  usleep

check_func_headers conio.h kbhit
check_func_headers io.h setmode
check_func_headers lzo/lzo1x.h lzo1x_999_compress
check_func_headers stdlib.h getenv
check_func_headers sys/stat.h lstat

check_func_headers windows.h CoTaskMemFree -lole32
check_func_headers windows.h GetProcessAffinityMask
check_func_headers windows.h GetProcessTimes
check_func_headers windows.h GetSystemTimeAsFileTime
check_func_headers windows.h LoadLibrary
check_func_headers windows.h MapViewOfFile
check_func_headers windows.h PeekNamedPipe
check_func_headers windows.h SetConsoleTextAttribute
check_func_headers windows.h SetConsoleCtrlHandler
check_func_headers windows.h Sleep
check_func_headers windows.h VirtualAlloc
check_struct windows.h "CONDITION_VARIABLE" Ptr
check_func_headers glob.h glob
enabled xlib &&
    check_func_headers "X11/Xlib.h X11/extensions/Xvlib.h" XvGetPortAttribute -lXv -lX11 -lXext

check_header AudioToolbox/AudioToolbox.h
check_header direct.h
check_header dirent.h
check_header dlfcn.h
check_header d3d11.h
check_header dxva.h
check_header dxva2api.h -D_WIN32_WINNT=0x0600
check_header io.h
check_header libcrystalhd/libcrystalhd_if.h
check_header mach/mach_time.h
check_header malloc.h
check_header net/udplite.h
check_header poll.h
check_header sys/mman.h
check_header sys/param.h
check_header sys/resource.h
check_header sys/select.h
check_header sys/time.h
check_header sys/un.h
check_header termios.h
check_header unistd.h
check_header valgrind/valgrind.h
check_header vdpau/vdpau.h
check_header vdpau/vdpau_x11.h
check_header VideoDecodeAcceleration/VDADecoder.h
check_header VideoToolbox/VideoToolbox.h
check_func_headers VideoToolbox/VTCompressionSession.h VTCompressionSessionPrepareToEncodeFrames -framework VideoToolbox
enabled videotoolbox && check_func_headers CoreVideo/CVImageBuffer.h kCVImageBufferColorPrimaries_ITU_R_2020 -framework CoreVideo
check_header windows.h
check_header X11/extensions/XvMClib.h
check_header asm/types.h

# it seems there are versions of clang in some distros that try to use the
# gcc headers, which explodes for stdatomic
# so we also check that atomics actually work here
check_builtin stdatomic_h stdatomic.h "atomic_int foo, bar = ATOMIC_VAR_INIT(-1); atomic_store(&foo, 0)"

check_lib "windows.h shellapi.h" CommandLineToArgvW   -lshell32
check_lib "windows.h wincrypt.h" CryptGenRandom       -ladvapi32
check_lib "windows.h psapi.h"    GetProcessMemoryInfo -lpsapi

check_lib "CoreServices/CoreServices.h" UTGetOSTypeFromString "-framework CoreServices"

check_struct "sys/time.h sys/resource.h" "struct rusage" ru_maxrss

check_type "windows.h dxva.h" "DXVA_PicParams_HEVC" -DWINAPI_FAMILY=WINAPI_FAMILY_DESKTOP_APP -D_CRT_BUILD_DESKTOP_APP=0
check_type "windows.h dxva.h" "DXVA_PicParams_VP9" -DWINAPI_FAMILY=WINAPI_FAMILY_DESKTOP_APP -D_CRT_BUILD_DESKTOP_APP=0
check_type "windows.h d3d11.h" "ID3D11VideoDecoder"
check_type "windows.h d3d11.h" "ID3D11VideoContext"
check_type "d3d9.h dxva2api.h" DXVA2_ConfigPictureDecode -D_WIN32_WINNT=0x0602

check_type "va/va.h va/va_dec_hevc.h" "VAPictureParameterBufferHEVC"
check_struct "va/va.h" "VADecPictureParameterBufferVP9" bit_depth
check_type "va/va.h va/va_vpp.h" "VAProcPipelineParameterBuffer"
check_type "va/va.h va/va_enc_h264.h" "VAEncPictureParameterBufferH264"
check_type "va/va.h va/va_enc_hevc.h" "VAEncPictureParameterBufferHEVC"
check_type "va/va.h va/va_enc_jpeg.h" "VAEncPictureParameterBufferJPEG"
check_type "va/va.h va/va_enc_mpeg2.h" "VAEncPictureParameterBufferMPEG2"
check_type "va/va.h va/va_enc_vp8.h"  "VAEncPictureParameterBufferVP8"

check_type "vdpau/vdpau.h" "VdpPictureInfoHEVC"

check_cpp_condition windows.h "!WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)" && enable winrt || disable winrt

if ! disabled w32threads && ! enabled pthreads; then
    check_func_headers "windows.h process.h" _beginthreadex &&
        enable w32threads || disable w32threads
    if ! enabled w32threads && enabled winrt; then
        check_func_headers "windows.h" CreateThread &&
            enable w32threads || disable w32threads
    fi
fi

# check for some common methods of building with pthread support
# do this before the optional library checks as some of them require pthreads
if ! disabled pthreads && ! enabled w32threads && ! enabled os2threads; then
    enable pthreads
    if check_func pthread_join -pthread && check_func pthread_create -pthread; then
        add_cflags -pthread
        add_extralibs -pthread
    elif check_func pthread_join -pthreads && check_func pthread_create -pthreads; then
        add_cflags -pthreads
        add_extralibs -pthreads
    elif check_func pthread_join -ldl -pthread && check_func pthread_create -ldl -pthread; then
        add_cflags -ldl -pthread
        add_extralibs -ldl -pthread
    elif check_func pthread_join -lpthreadGC2 && check_func pthread_create -lpthreadGC2; then
        add_extralibs -lpthreadGC2
    elif check_lib pthread.h pthread_join -lpthread && check_lib pthread.h pthread_create -lpthread; then
        :
    elif ! check_func pthread_join && ! check_func pthread_create; then
        disable pthreads
    fi
    check_code cc "pthread.h" "static pthread_mutex_t atomic_lock = PTHREAD_MUTEX_INITIALIZER" || disable pthreads
fi


if enabled pthreads; then
  check_func pthread_cancel
fi

enabled pthreads &&
    check_builtin sem_timedwait semaphore.h "sem_t *s; sem_init(s,0,0); sem_timedwait(s,0); sem_destroy(s)"

disabled  zlib || check_lib  zlib.h      zlibVersion    -lz    || disable  zlib
disabled bzlib || check_lib bzlib.h BZ2_bzlibVersion    -lbz2  || disable bzlib
disabled  lzma || check_lib  lzma.h lzma_version_number -llzma || disable lzma

check_lib math.h sin -lm && LIBM="-lm"
disabled crystalhd || check_lib "stdint.h libcrystalhd/libcrystalhd_if.h" DtsCrystalHDVersion -lcrystalhd || disable crystalhd

atan2f_args=2
copysign_args=2
hypot_args=2
ldexpf_args=2
powf_args=2

for func in $MATH_FUNCS; do
    eval check_mathfunc $func \${${func}_args:-1}
done

for func in $COMPLEX_FUNCS; do
    eval check_complexfunc $func \${${func}_args:-1}
done

# these are off by default, so fail if requested and not available
enabled avfoundation_indev && { check_header_objcc AVFoundation/AVFoundation.h || disable avfoundation_indev; }
enabled avfoundation_indev && { check_lib CoreGraphics/CoreGraphics.h CGGetActiveDisplayList -framework CoreGraphics ||
                                check_lib ApplicationServices/ApplicationServices.h CGGetActiveDisplayList -framework ApplicationServices; }
enabled cuda              && check_header cuda.h # this is not a dependency
enabled cuvid             && { enabled cuda ||
                               die "ERROR: CUVID requires CUDA"; }
enabled chromaprint       && require chromaprint chromaprint.h chromaprint_get_version -lchromaprint
enabled coreimage_filter  && { check_header_objcc QuartzCore/CoreImage.h || disable coreimage_filter; }
enabled coreimagesrc_filter && { check_header_objcc QuartzCore/CoreImage.h || disable coreimagesrc_filter; }
enabled decklink          && { { check_header DeckLinkAPI.h || die "ERROR: DeckLinkAPI.h header not found"; } &&
                               { check_cpp_condition DeckLinkAPIVersion.h "BLACKMAGIC_DECKLINK_API_VERSION >= 0x0a060100" || die "ERROR: Decklink API version must be >= 10.6.1."; } }
enabled frei0r            && { check_header frei0r.h || die "ERROR: frei0r.h header not found"; }
enabled gmp               && require gmp gmp.h mpz_export -lgmp
enabled gnutls            && require_pkg_config gnutls gnutls/gnutls.h gnutls_global_init
enabled jni               && { [ $target_os = "android" ] && check_header jni.h && enabled pthreads &&
                               check_lib "dlfcn.h" dlopen -ldl || die "ERROR: jni not found"; }
enabled ladspa            && { check_header ladspa.h || die "ERROR: ladspa.h header not found"; }
enabled libiec61883       && require libiec61883 libiec61883/iec61883.h iec61883_cmp_connect -lraw1394 -lavc1394 -lrom1394 -liec61883
enabled libass            && require_pkg_config libass ass/ass.h ass_library_init
enabled libbluray         && require_pkg_config libbluray libbluray/bluray.h bd_open
enabled libbs2b           && require_pkg_config libbs2b bs2b.h bs2b_open
enabled libcelt           && require libcelt celt/celt.h celt_decode -lcelt0 &&
                             { check_lib celt/celt.h celt_decoder_create_custom -lcelt0 ||
                               die "ERROR: libcelt must be installed and version must be >= 0.11.0."; }
enabled libcaca           && require_pkg_config caca caca.h caca_create_canvas
enabled libfdk_aac        && { use_pkg_config fdk-aac "fdk-aac/aacenc_lib.h" aacEncOpen ||
                               { require libfdk_aac fdk-aac/aacenc_lib.h aacEncOpen -lfdk-aac &&
                                 warn "using libfdk without pkg-config"; } }
flite_libs="-lflite_cmu_time_awb -lflite_cmu_us_awb -lflite_cmu_us_kal -lflite_cmu_us_kal16 -lflite_cmu_us_rms -lflite_cmu_us_slt -lflite_usenglish -lflite_cmulex -lflite"
enabled libflite          && require libflite "flite/flite.h" flite_init $flite_libs
enabled fontconfig        && enable libfontconfig
enabled libfontconfig     && require_pkg_config fontconfig "fontconfig/fontconfig.h" FcInit
enabled libfreetype       && require_libfreetype
enabled libfribidi        && require_pkg_config fribidi fribidi.h fribidi_version_info
enabled libgme            && require  libgme gme/gme.h gme_new_emu -lgme -lstdc++
enabled libgsm            && { for gsm_hdr in "gsm.h" "gsm/gsm.h"; do
                                   check_lib "${gsm_hdr}" gsm_create -lgsm && break;
                               done || die "ERROR: libgsm not found"; }
enabled libilbc           && require libilbc ilbc.h WebRtcIlbcfix_InitDecode -lilbc
enabled libkvazaar        && require_pkg_config "kvazaar >= 0.8.1" kvazaar.h kvz_api_get
enabled libmfx            && require_pkg_config libmfx "mfx/mfxvideo.h" MFXInit
enabled libmodplug        && require_pkg_config libmodplug libmodplug/modplug.h ModPlug_Load
enabled libmp3lame        && require "libmp3lame >= 3.98.3" lame/lame.h lame_set_VBR_quality -lmp3lame
enabled libnut            && require libnut libnut.h nut_demuxer_init -lnut
enabled libnpp            && require libnpp npp.h nppGetLibVersion -lnppi -lnppc
enabled libopencore_amrnb && require libopencore_amrnb opencore-amrnb/interf_dec.h Decoder_Interface_init -lopencore-amrnb
enabled libopencore_amrwb && require libopencore_amrwb opencore-amrwb/dec_if.h D_IF_init -lopencore-amrwb
enabled libopencv         && { check_header opencv2/core/core_c.h &&
                               { use_pkg_config opencv opencv2/core/core_c.h cvCreateImageHeader ||
                                 require opencv opencv2/core/core_c.h cvCreateImageHeader -lopencv_core -lopencv_imgproc; } ||
                               require_pkg_config opencv opencv/cxcore.h cvCreateImageHeader; }
enabled libopenh264       && require_pkg_config openh264 wels/codec_api.h WelsGetCodecVersion
enabled libopenjpeg       && { { check_lib openjpeg-2.1/openjpeg.h opj_version -lopenjp2 -DOPJ_STATIC && add_cppflags -DOPJ_STATIC; } ||
                               check_lib openjpeg-2.1/openjpeg.h opj_version -lopenjp2 ||
                               { check_lib openjpeg-2.0/openjpeg.h opj_version -lopenjp2 -DOPJ_STATIC && add_cppflags -DOPJ_STATIC; } ||
                               { check_lib openjpeg-1.5/openjpeg.h opj_version -lopenjpeg -DOPJ_STATIC && add_cppflags -DOPJ_STATIC; } ||
                               { check_lib openjpeg.h opj_version -lopenjpeg -DOPJ_STATIC && add_cppflags -DOPJ_STATIC; } ||
                               die "ERROR: libopenjpeg not found"; }
enabled libopenmpt        && require_pkg_config "libopenmpt >= 0.2.6557" libopenmpt/libopenmpt.h openmpt_module_create
enabled libopus           && require_pkg_config opus opus_multistream.h opus_multistream_decoder_create
enabled libpulse          && require_pkg_config libpulse pulse/pulseaudio.h pa_context_new
enabled librtmp           && require_pkg_config librtmp librtmp/rtmp.h RTMP_Socket
enabled librubberband     && require_pkg_config "rubberband >= 1.8.1" rubberband/rubberband-c.h rubberband_new
enabled libschroedinger   && require_pkg_config schroedinger-1.0 schroedinger/schro.h schro_init
enabled libshine          && require_pkg_config shine shine/layer3.h shine_encode_buffer
enabled libsmbclient      && { use_pkg_config smbclient libsmbclient.h smbc_init ||
                               require smbclient libsmbclient.h smbc_init -lsmbclient; }
enabled libsnappy         && require snappy snappy-c.h snappy_compress -lsnappy
enabled libsoxr           && require libsoxr soxr.h soxr_create -lsoxr && LIBSOXR="-lsoxr"
enabled libssh            && require_pkg_config libssh libssh/sftp.h sftp_init
enabled libspeex          && require_pkg_config speex speex/speex.h speex_decoder_init -lspeex
enabled libtesseract      && require_pkg_config tesseract tesseract/capi.h TessBaseAPICreate
enabled libtheora         && require libtheora theora/theoraenc.h th_info_init -ltheoraenc -ltheoradec -logg
enabled libtwolame        && require libtwolame twolame.h twolame_init -ltwolame &&
                             { check_lib twolame.h twolame_encode_buffer_float32_interleaved -ltwolame ||
                               die "ERROR: libtwolame must be installed and version must be >= 0.3.10"; }
enabled libv4l2           && require_pkg_config libv4l2 libv4l2.h v4l2_ioctl
enabled libvidstab        && require_pkg_config "vidstab >= 0.98" vid.stab/libvidstab.h vsMotionDetectInit
enabled libvo_amrwbenc    && require libvo_amrwbenc vo-amrwbenc/enc_if.h E_IF_init -lvo-amrwbenc
enabled libvorbis         && require libvorbis vorbis/vorbisenc.h vorbis_info_init -lvorbisenc -lvorbis -logg

enabled libvpx            && {
    enabled libvpx_vp8_decoder && {
        use_pkg_config "vpx >= 0.9.1" "vpx/vpx_decoder.h vpx/vp8dx.h" vpx_codec_vp8_dx ||
            check_lib "vpx/vpx_decoder.h vpx/vp8dx.h" vpx_codec_dec_init_ver -lvpx ||
                die "ERROR: libvpx decoder version must be >=0.9.1";
    }
    enabled libvpx_vp8_encoder && {
        use_pkg_config "vpx >= 0.9.7" "vpx/vpx_encoder.h vpx/vp8cx.h" vpx_codec_vp8_cx ||
            check_lib "vpx/vpx_encoder.h vpx/vp8cx.h" "vpx_codec_enc_init_ver VP8E_SET_MAX_INTRA_BITRATE_PCT" -lvpx ||
                die "ERROR: libvpx encoder version must be >=0.9.7";
    }
    enabled libvpx_vp9_decoder && {
        use_pkg_config "vpx >= 1.3.0" "vpx/vpx_decoder.h vpx/vp8dx.h" vpx_codec_vp9_dx ||
            check_lib "vpx/vpx_decoder.h vpx/vp8dx.h" "vpx_codec_vp9_dx" -lvpx ||
                disable libvpx_vp9_decoder;
    }
    enabled libvpx_vp9_encoder && {
        use_pkg_config "vpx >= 1.3.0" "vpx/vpx_encoder.h vpx/vp8cx.h" vpx_codec_vp9_cx ||
            check_lib "vpx/vpx_encoder.h vpx/vp8cx.h" "vpx_codec_vp9_cx VP9E_SET_AQ_MODE" -lvpx ||
                disable libvpx_vp9_encoder;
    }
    if disabled_all libvpx_vp8_decoder libvpx_vp9_decoder libvpx_vp8_encoder libvpx_vp9_encoder; then
        die "libvpx enabled but no supported decoders found"
    fi
}

enabled libwavpack        && require libwavpack wavpack/wavpack.h WavpackOpenFileOutput  -lwavpack
enabled libwebp           && {
    enabled libwebp_encoder      && require_pkg_config "libwebp >= 0.2.0" webp/encode.h WebPGetEncoderVersion
    enabled libwebp_anim_encoder && { use_pkg_config "libwebpmux >= 0.4.0" webp/mux.h WebPAnimEncoderOptionsInit || disable libwebp_anim_encoder; } }
enabled libx264           && { use_pkg_config x264 "stdint.h x264.h" x264_encoder_encode ||
                               { require libx264 "stdint.h x264.h" x264_encoder_encode -lx264 &&
                                 warn "using libx264 without pkg-config"; } } &&
                             { check_cpp_condition x264.h "X264_BUILD >= 118" ||
                               die "ERROR: libx264 must be installed and version must be >= 0.118."; } &&
                             { check_cpp_condition x264.h "X264_MPEG2" &&
                               enable libx262; }
enabled libx265           && require_pkg_config x265 x265.h x265_api_get &&
                             { check_cpp_condition x265.h "X265_BUILD >= 68" ||
                               die "ERROR: libx265 version must be >= 68."; }
enabled libxavs           && require libxavs "stdint.h xavs.h" xavs_encoder_encode -lxavs
enabled libxvid           && require libxvid xvid.h xvid_global -lxvidcore
enabled libzimg           && require_pkg_config "zimg >= 2.3.0" zimg.h zimg_get_api_version
enabled libzmq            && require_pkg_config libzmq zmq.h zmq_ctx_new
enabled libzvbi           && require libzvbi libzvbi.h vbi_decoder_new -lzvbi &&
                             { check_cpp_condition libzvbi.h "VBI_VERSION_MAJOR > 0 || VBI_VERSION_MINOR > 2 || VBI_VERSION_MINOR == 2 && VBI_VERSION_MICRO >= 28" ||
                               enabled gpl || die "ERROR: libzvbi requires version 0.2.28 or --enable-gpl."; }
enabled mediacodec        && { enabled jni || die "ERROR: mediacodec requires --enable-jni"; }
enabled mmal              && { check_lib interface/mmal/mmal.h mmal_port_connect -lmmal_core -lmmal_util -lmmal_vc_client -lbcm_host ||
                                { ! enabled cross_compile && {
                                    add_cflags -isystem/opt/vc/include/ -isystem/opt/vc/include/interface/vmcs_host/linux -isystem/opt/vc/include/interface/vcos/pthreads -fgnu89-inline ;
                                    add_extralibs -L/opt/vc/lib/ -lmmal_core -lmmal_util -lmmal_vc_client -lbcm_host ;
                                    check_lib interface/mmal/mmal.h mmal_port_connect ; }
                                check_lib interface/mmal/mmal.h mmal_port_connect ; } ||
                               die "ERROR: mmal not found"; }
enabled mmal && check_func_headers interface/mmal/mmal.h "MMAL_PARAMETER_VIDEO_MAX_NUM_CALLBACKS"

enabled netcdf            && require_pkg_config netcdf netcdf.h nc_inq_libvers
enabled openal            && { { for al_libs in "${OPENAL_LIBS}" "-lopenal" "-lOpenAL32"; do
                               check_lib 'AL/al.h' alGetError "${al_libs}" && break; done } ||
                               die "ERROR: openal not found"; } &&
                             { check_cpp_condition "AL/al.h" "defined(AL_VERSION_1_1)" ||
                               die "ERROR: openal must be installed and version must be 1.1 or compatible"; }
enabled opencl            && { check_lib OpenCL/cl.h clEnqueueNDRangeKernel -Wl,-framework,OpenCL ||
                               check_lib CL/cl.h clEnqueueNDRangeKernel -lOpenCL ||
                               die "ERROR: opencl not found"; } &&
                             { check_cpp_condition "OpenCL/cl.h" "defined(CL_VERSION_1_2)" ||
                               check_cpp_condition "CL/cl.h" "defined(CL_VERSION_1_2)" ||
                               die "ERROR: opencl must be installed and version must be 1.2 or compatible"; }
enabled opengl            && { check_lib GL/glx.h glXGetProcAddress "-lGL" ||
                               check_lib windows.h wglGetProcAddress "-lopengl32 -lgdi32" ||
                               check_lib OpenGL/gl3.h glGetError "-Wl,-framework,OpenGL" ||
                               check_lib ES2/gl.h glGetError "-isysroot=${sysroot} -Wl,-framework,OpenGLES" ||
                               die "ERROR: opengl not found."
                             }
enabled omx_rpi && enable omx
enabled omx               && { check_header OMX_Core.h ||
                                { ! enabled cross_compile && enabled omx_rpi && {
                                    add_cflags -isystem/opt/vc/include/IL ; }
                                check_header OMX_Core.h ; } ||
                               die "ERROR: OpenMAX IL headers not found"; }
enabled openssl           && { use_pkg_config openssl openssl/ssl.h OPENSSL_init_ssl ||
                               use_pkg_config openssl openssl/ssl.h SSL_library_init ||
                               check_lib openssl/ssl.h SSL_library_init -lssl -lcrypto ||
                               check_lib openssl/ssl.h SSL_library_init -lssl32 -leay32 ||
                               check_lib openssl/ssl.h SSL_library_init -lssl -lcrypto -lws2_32 -lgdi32 ||
                               die "ERROR: openssl not found"; }
enabled qtkit_indev      && { check_header_objcc QTKit/QTKit.h || disable qtkit_indev; }

# libdc1394 check
if enabled libdc1394; then
    { require_pkg_config libdc1394-2 dc1394/dc1394.h dc1394_new &&
        enable libdc1394_2; } ||
    { check_lib libdc1394/dc1394_control.h dc1394_create_handle -ldc1394_control -lraw1394 &&
        enable libdc1394_1; } ||
    die "ERROR: No version of libdc1394 found "
fi

if enabled gcrypt; then
    GCRYPT_CONFIG="${cross_prefix}libgcrypt-config"
    if "${GCRYPT_CONFIG}" --version > /dev/null 2>&1; then
        gcrypt_cflags=$("${GCRYPT_CONFIG}" --cflags)
        gcrypt_libs=$("${GCRYPT_CONFIG}" --libs)
        check_func_headers gcrypt.h gcry_mpi_new $gcrypt_cflags $gcrypt_libs ||
            die "ERROR: gcrypt not found"
        add_cflags $gcrypt_cflags && add_extralibs $gcrypt_libs
    else
        require gcrypt gcrypt.h gcry_mpi_new -lgcrypt
    fi
fi

disabled sdl && disable sdl2
if ! disabled sdl2; then
    SDL2_CONFIG="${cross_prefix}sdl2-config"
    if check_pkg_config sdl2 SDL_events.h SDL_PollEvent; then
        check_cpp_condition SDL.h "(SDL_MAJOR_VERSION<<16 | SDL_MINOR_VERSION<<8 | SDL_PATCHLEVEL) >= 0x020001" $sdl2_cflags &&
        check_cpp_condition SDL.h "(SDL_MAJOR_VERSION<<16 | SDL_MINOR_VERSION<<8 | SDL_PATCHLEVEL) < 0x020100" $sdl2_cflags &&
        check_func SDL_Init $sdl2_libs $sdl2_cflags && enable sdl2
    else
      if "${SDL2_CONFIG}" --version > /dev/null 2>&1; then
        sdl2_cflags=$("${SDL2_CONFIG}" --cflags)
        sdl2_libs=$("${SDL2_CONFIG}" --libs)
        check_cpp_condition SDL.h "(SDL_MAJOR_VERSION<<16 | SDL_MINOR_VERSION<<8 | SDL_PATCHLEVEL) >= 0x020001" $sdl2_cflags &&
        check_cpp_condition SDL.h "(SDL_MAJOR_VERSION<<16 | SDL_MINOR_VERSION<<8 | SDL_PATCHLEVEL) < 0x020100" $sdl2_cflags &&
        check_func SDL_Init $sdl2_libs $sdl2_cflags && enable sdl2
      fi
    fi
    if test $target_os = "mingw32"; then
        sdl2_libs="$sdl2_libs -mconsole"
    fi
fi
enabled sdl2 && enable sdl && add_cflags $sdl2_cflags && add_extralibs $sdl2_libs

disabled securetransport || { check_func SecIdentityCreate "-Wl,-framework,CoreFoundation -Wl,-framework,Security" &&
    check_lib "Security/SecureTransport.h Security/Security.h" "SSLCreateContext SecItemImport" "-Wl,-framework,CoreFoundation -Wl,-framework,Security" &&
    enable securetransport; }

disabled schannel || { check_func_headers "windows.h security.h" InitializeSecurityContext -DSECURITY_WIN32 -lsecur32 &&
                       check_cpp_condition winerror.h "defined(SEC_I_CONTEXT_EXPIRED)" && enable schannel && add_extralibs -lsecur32; }

makeinfo --version > /dev/null 2>&1 && enable makeinfo  || disable makeinfo
enabled makeinfo \
    && [ 0$(makeinfo --version | grep "texinfo" | sed 's/.*texinfo[^0-9]*\([0-9]*\)\..*/\1/') -ge 5 ] \
    && enable makeinfo_html || disable makeinfo_html
disabled makeinfo_html && texi2html --help 2> /dev/null | grep -q 'init-file' && enable texi2html || disable texi2html
perl -v            > /dev/null 2>&1 && enable perl      || disable perl
pod2man --help     > /dev/null 2>&1 && enable pod2man   || disable pod2man
rsync --help 2> /dev/null | grep -q 'contimeout' && enable rsync_contimeout || disable rsync_contimeout

check_header linux/fb.h
check_header linux/videodev.h
check_header linux/videodev2.h
check_code cc linux/videodev2.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_safe struct_v4l2_frmivalenum_discrete

check_header sys/videoio.h
check_code cc sys/videoio.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_safe struct_v4l2_frmivalenum_discrete

check_func_headers "windows.h vfw.h" capCreateCaptureWindow "$vfwcap_indev_extralibs"
# check that WM_CAP_DRIVER_CONNECT is defined to the proper value
# w32api 3.12 had it defined wrong
check_cpp_condition vfw.h "WM_CAP_DRIVER_CONNECT > WM_USER" && enable vfwcap_defines

check_type "dshow.h" IBaseFilter

# check for ioctl_meteor.h, ioctl_bt848.h and alternatives
{ check_header dev/bktr/ioctl_meteor.h &&
  check_header dev/bktr/ioctl_bt848.h; } ||
{ check_header machine/ioctl_meteor.h &&
  check_header machine/ioctl_bt848.h; } ||
{ check_header dev/video/meteor/ioctl_meteor.h &&