1 files changed, 263 insertions, 10 deletions

diff --git a/media/ffvpx/compat/w32pthreads.h b/media/ffvpx/compat/w32pthreads.h
index 21acfd2ba..eeead6051 100644
--- a/media/ffvpx/compat/w32pthreads.h
+++ b/media/ffvpx/compat/w32pthreads.h
@@ -39,6 +39,11 @@
 #include <windows.h>
 #include <process.h>
 
+#if _WIN32_WINNT < 0x0600 && defined(__MINGW32__)
+#undef MemoryBarrier
+#define MemoryBarrier __sync_synchronize
+#endif
+
 #include "libavutil/attributes.h"
 #include "libavutil/common.h"
 #include "libavutil/internal.h"
@@ -51,15 +56,24 @@ typedef struct pthread_t {
     void *ret;
 } pthread_t;
 
-/* use light weight mutex/condition variable API for Windows Vista and later */
-typedef SRWLOCK pthread_mutex_t;
-typedef CONDITION_VARIABLE pthread_cond_t;
+/* the conditional variable api for windows 6.0+ uses critical sections and
+ * not mutexes */
+typedef CRITICAL_SECTION pthread_mutex_t;
 
-#define PTHREAD_MUTEX_INITIALIZER SRWLOCK_INIT
-#define PTHREAD_COND_INITIALIZER CONDITION_VARIABLE_INIT
+/* This is the CONDITION_VARIABLE typedef for using Windows' native
+ * conditional variables on kernels 6.0+. */
+#if HAVE_CONDITION_VARIABLE_PTR
+typedef CONDITION_VARIABLE pthread_cond_t;
+#else
+typedef struct pthread_cond_t {
+    void *Ptr;
+} pthread_cond_t;
+#endif
 
+#if _WIN32_WINNT >= 0x0600
 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
+#endif
 
 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
 {
@@ -100,25 +114,26 @@ static av_unused int pthread_join(pthread_t thread, void **value_ptr)
 
 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 {
-    InitializeSRWLock(m);
+    InitializeCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 {
-    /* Unlocked SWR locks use no resources */
+    DeleteCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 {
-    AcquireSRWLockExclusive(m);
+    EnterCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 {
-    ReleaseSRWLockExclusive(m);
+    LeaveCriticalSection(m);
     return 0;
 }
 
+#if _WIN32_WINNT >= 0x0600
 typedef INIT_ONCE pthread_once_t;
 #define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
 
@@ -152,7 +167,7 @@ static inline int pthread_cond_broadcast(pthread_cond_t *cond)
 
 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 {
-    SleepConditionVariableSRW(cond, mutex, INFINITE, 0);
+    SleepConditionVariableCS(cond, mutex, INFINITE);
     return 0;
 }
 
@@ -162,4 +177,242 @@ static inline int pthread_cond_signal(pthread_cond_t *cond)
     return 0;
 }
 
+#else // _WIN32_WINNT < 0x0600
+
+/* atomic init state of dynamically loaded functions */
+static LONG w32thread_init_state = 0;
+static av_unused void w32thread_init(void);
+
+/* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
+ * compatible to the one used in the native API */
+
+typedef union pthread_once_t  {
+    void * Ptr;    ///< For the Windows 6.0+ native functions
+    LONG state;    ///< For the pre-Windows 6.0 compat code
+} pthread_once_t;
+
+#define PTHREAD_ONCE_INIT {0}
+
+/* function pointers to init once API on windows 6.0+ kernels */
+static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
+static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
+
+/* pre-Windows 6.0 compat using a spin-lock */
+static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
+{
+    switch (InterlockedCompareExchange(state, 1, 0)) {
+    /* Initial run */
+    case 0:
+        init_routine();
+        InterlockedExchange(state, 2);
+        break;
+    /* Another thread is running init */
+    case 1:
+        while (1) {
+            MemoryBarrier();
+            if (*state == 2)
+                break;
+            Sleep(0);
+        }
+        break;
+    /* Initialization complete */
+    case 2:
+        break;
+    }
+}
+
+static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
+{
+    w32thread_once_fallback(&w32thread_init_state, w32thread_init);
+
+    /* Use native functions on Windows 6.0+ */
+    if (initonce_begin && initonce_complete) {
+        BOOL pending = FALSE;
+        initonce_begin(once_control, 0, &pending, NULL);
+        if (pending)
+            init_routine();
+        initonce_complete(once_control, 0, NULL);
+        return 0;
+    }
+
+    w32thread_once_fallback(&once_control->state, init_routine);
+    return 0;
+}
+
+/* for pre-Windows 6.0 platforms we need to define and use our own condition
+ * variable and api */
+
+typedef struct  win32_cond_t {
+    pthread_mutex_t mtx_broadcast;
+    pthread_mutex_t mtx_waiter_count;
+    volatile int waiter_count;
+    HANDLE semaphore;
+    HANDLE waiters_done;
+    volatile int is_broadcast;
+} win32_cond_t;
+
+/* function pointers to conditional variable API on windows 6.0+ kernels */
+static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
+static void (WINAPI *cond_init)(pthread_cond_t *cond);
+static void (WINAPI *cond_signal)(pthread_cond_t *cond);
+static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
+                                DWORD milliseconds);
+
+static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
+{
+    win32_cond_t *win32_cond = NULL;
+
+    w32thread_once_fallback(&w32thread_init_state, w32thread_init);
+
+    if (cond_init) {
+        cond_init(cond);
+        return 0;
+    }
+
+    /* non native condition variables */
+    win32_cond = (win32_cond_t*)av_mallocz(sizeof(win32_cond_t));
+    if (!win32_cond)
+        return ENOMEM;
+    cond->Ptr = win32_cond;
+    win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
+    if (!win32_cond->semaphore)
+        return ENOMEM;
+    win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
+    if (!win32_cond->waiters_done)
+        return ENOMEM;
+
+    pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
+    pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
+    return 0;
+}
+
+static av_unused int pthread_cond_destroy(pthread_cond_t *cond)
+{
+    win32_cond_t *win32_cond = (win32_cond_t*)cond->Ptr;
+    /* native condition variables do not destroy */
+    if (cond_init)
+        return 0;
+
+    /* non native condition variables */
+    CloseHandle(win32_cond->semaphore);
+    CloseHandle(win32_cond->waiters_done);
+    pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
+    pthread_mutex_destroy(&win32_cond->mtx_broadcast);
+    av_freep(&win32_cond);
+    cond->Ptr = NULL;
+    return 0;
+}
+
+static av_unused int pthread_cond_broadcast(pthread_cond_t *cond)
+{
+    win32_cond_t *win32_cond = (win32_cond_t*)cond->Ptr;
+    int have_waiter;
+
+    if (cond_broadcast) {
+        cond_broadcast(cond);
+        return 0;
+    }
+
+    /* non native condition variables */
+    pthread_mutex_lock(&win32_cond->mtx_broadcast);
+    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
+    have_waiter = 0;
+
+    if (win32_cond->waiter_count) {
+        win32_cond->is_broadcast = 1;
+        have_waiter = 1;
+    }
+
+    if (have_waiter) {
+        ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
+        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
+        ResetEvent(win32_cond->waiters_done);
+        win32_cond->is_broadcast = 0;
+    } else
+        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
+    return 0;
+}
+
+static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
+{
+    win32_cond_t *win32_cond = (win32_cond_t*)cond->Ptr;
+    int last_waiter;
+    if (cond_wait) {
+        cond_wait(cond, mutex, INFINITE);
+        return 0;
+    }
+
+    /* non native condition variables */
+    pthread_mutex_lock(&win32_cond->mtx_broadcast);
+    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
+    win32_cond->waiter_count++;
+    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
+
+    // unlock the external mutex
+    pthread_mutex_unlock(mutex);
+    WaitForSingleObject(win32_cond->semaphore, INFINITE);
+
+    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
+    win32_cond->waiter_count--;
+    last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
+    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+
+    if (last_waiter)
+        SetEvent(win32_cond->waiters_done);
+
+    // lock the external mutex
+    return pthread_mutex_lock(mutex);
+}
+
+static av_unused int pthread_cond_signal(pthread_cond_t *cond)
+{
+    win32_cond_t *win32_cond = (win32_cond_t*)cond->Ptr;
+    int have_waiter;
+    if (cond_signal) {
+        cond_signal(cond);
+        return 0;
+    }
+
+    pthread_mutex_lock(&win32_cond->mtx_broadcast);
+
+    /* non-native condition variables */
+    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
+    have_waiter = win32_cond->waiter_count;
+    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+
+    if (have_waiter) {
+        ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
+        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
+        ResetEvent(win32_cond->waiters_done);
+    }
+
+    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
+    return 0;
+}
+#endif
+
+static av_unused void w32thread_init(void)
+{
+#if _WIN32_WINNT < 0x0600
+    HMODULE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
+    /* if one is available, then they should all be available */
+    cond_init      = (void (WINAPI*)(pthread_cond_t *))
+        GetProcAddress(kernel_dll, "InitializeConditionVariable");
+    cond_broadcast = (void (WINAPI*)(pthread_cond_t *))
+        GetProcAddress(kernel_dll, "WakeAllConditionVariable");
+    cond_signal    = (void (WINAPI*)(pthread_cond_t *))
+        GetProcAddress(kernel_dll, "WakeConditionVariable");
+    cond_wait      = (BOOL (WINAPI*)(pthread_cond_t *, pthread_mutex_t *, DWORD))
+        GetProcAddress(kernel_dll, "SleepConditionVariableCS");
+    initonce_begin = (BOOL (WINAPI*)(pthread_once_t *, DWORD, BOOL *, void **))
+        GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
+    initonce_complete = (BOOL (WINAPI*)(pthread_once_t *, DWORD, void *))
+        GetProcAddress(kernel_dll, "InitOnceComplete");
+#endif
+
+}
+
 #endif /* COMPAT_W32PTHREADS_H */