/*
  * Copyright (C) 2010-2011 x264 project
  *
  * Authors: Steven Walters <kemuri9@gmail.com>
  *          Pegasys Inc. <http://www.pegasys-inc.com>
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * w32threads to pthreads wrapper
  */
 

 #ifndef FFMPEG_COMPAT_W32PTHREADS_H
 #define FFMPEG_COMPAT_W32PTHREADS_H

 
 /* Build up a pthread-like API using underlying Windows API. Have only static
  * methods so as to not conflict with a potentially linked in pthread-win32
  * library.
  * As most functions here are used without checking return values,
  * only implement return values as necessary. */
 
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <process.h>
 

 #include "libavutil/attributes.h"

 #include "libavutil/common.h"

 #include "libavutil/internal.h"
 #include "libavutil/mem.h"

 typedef struct pthread_t {

     void *handle;
     void *(*func)(void* arg);
     void *arg;
     void *ret;
 } pthread_t;
 
 /* the conditional variable api for windows 6.0+ uses critical sections and
  * not mutexes */
 typedef CRITICAL_SECTION pthread_mutex_t;
 
 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
  * conditional variables on kernels 6.0+.
  * MinGW does not currently have this typedef. */

 typedef struct pthread_cond_t {

     void *ptr;
 } pthread_cond_t;
 
 /* function pointers to conditional variable API on windows 6.0+ kernels */

 #if _WIN32_WINNT < 0x0600

 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);

 #else
 #define cond_init      InitializeConditionVariable
 #define cond_broadcast WakeAllConditionVariable
 #define cond_signal    WakeConditionVariable
 #define cond_wait      SleepConditionVariableCS

 
 #define CreateEvent(a, reset, init, name)                   \
     CreateEventEx(a, name,                                  \
                   (reset ? CREATE_EVENT_MANUAL_RESET : 0) | \
                   (init ? CREATE_EVENT_INITIAL_SET : 0),    \
                   EVENT_ALL_ACCESS)
 // CreateSemaphoreExA seems to be desktop-only, but as long as we don't
 // use named semaphores, it doesn't matter if we use the W version.
 #define CreateSemaphore(a, b, c, d) \
     CreateSemaphoreExW(a, b, c, d, 0, SEMAPHORE_ALL_ACCESS)
 #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)

 {
     pthread_t *h = arg;
     h->ret = h->func(h->arg);
     return 0;
 }
 

 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
                                     void *(*start_routine)(void*), void *arg)

 {
     thread->func   = start_routine;
     thread->arg    = arg;
     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
                                            0, NULL);
     return !thread->handle;
 }
 

 static av_unused void pthread_join(pthread_t thread, void **value_ptr)

 {
     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
     if (ret != WAIT_OBJECT_0)
         return;
     if (value_ptr)
         *value_ptr = thread.ret;
     CloseHandle(thread.handle);
 }
 

 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 {
     InitializeCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 {
     DeleteCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 {
     EnterCriticalSection(m);
     return 0;
 }
 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 {
     LeaveCriticalSection(m);
     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;
 

 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)

 {
     win32_cond_t *win32_cond = NULL;

     if (cond_init) {

         cond_init(cond);

         return 0;

     }
 
     /* non native condition variables */
     win32_cond = 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 void pthread_cond_destroy(pthread_cond_t *cond)

 {
     win32_cond_t *win32_cond = cond->ptr;
     /* native condition variables do not destroy */

     if (cond_init)

         return;
 
     /* 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;
 }
 

 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)

 {
     win32_cond_t *win32_cond = cond->ptr;

     int have_waiter;
 

     if (cond_broadcast) {

         cond_broadcast(cond);
         return;
     }
 
     /* 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);

 }
 

 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)

 {
     win32_cond_t *win32_cond = 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 void pthread_cond_signal(pthread_cond_t *cond)

 {
     win32_cond_t *win32_cond = cond->ptr;

     int have_waiter;

     if (cond_signal) {

         cond_signal(cond);
         return;
     }
 

     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);

 }
 

 static av_unused void w32thread_init(void)

 {

 #if _WIN32_WINNT < 0x0600

     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
     /* if one is available, then they should all be available */
     cond_init      =
         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
     cond_broadcast =
         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
     cond_signal    =
         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
     cond_wait      =
         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");

 #endif
 

 }
 

 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */