winrt: multithreading support

_beginthreadex is for desktop only. CreateThread is available for windows store apps on windows (and phone) 8.1 and later. http://msdn.microsoft.com/en-us/library/ms682453%28VS.85%29.aspx

Signed-off-by: Matt Oliver <protogonoi@gmail.com>

compat/w32pthreads.h

@@ -82,8 +82,13 @@ static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
 {
     thread->func   = start_routine;
     thread->arg    = arg;
+#if HAVE_WINRT
+    thread->handle = (void*)CreateThread(NULL, 0, win32thread_worker, thread,
+                                           0, NULL);
+#else
     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
                                            0, NULL);
+#endif
     return !thread->handle;
 }
 

configure

@@ -1904,6 +1904,7 @@ HAVE_LIST="
     dos_paths
     dxva2api_cobj
     dxva2_lib
+    winrt
     libc_msvcrt
     libdc1394_1
     libdc1394_2
@@ -5236,9 +5237,15 @@ check_type "va/va.h" "VAPictureParameterBufferHEVC"
 
 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

libavutil/cpu.c

@@ -30,7 +30,7 @@
 #endif
 #include <sched.h>
 #endif
-#if HAVE_GETPROCESSAFFINITYMASK
+#if HAVE_GETPROCESSAFFINITYMASK || HAVE_WINRT
 #include <windows.h>
 #endif
 #if HAVE_SYSCTL
@@ -253,6 +253,9 @@ int av_cpu_count(void)
     static volatile int printed;
 
     int nb_cpus = 1;
+#if HAVE_WINRT
+    SYSTEM_INFO sysinfo;
+#endif
 #if HAVE_SCHED_GETAFFINITY && defined(CPU_COUNT)
     cpu_set_t cpuset;
 
@@ -274,6 +277,9 @@ int av_cpu_count(void)
     nb_cpus = sysconf(_SC_NPROC_ONLN);
 #elif HAVE_SYSCONF && defined(_SC_NPROCESSORS_ONLN)
     nb_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+#elif HAVE_WINRT
+    GetNativeSystemInfo(&sysinfo);
+    nb_cpus = sysinfo.dwNumberOfProcessors;
 #endif
 
     if (!printed) {