1/*
2 * Copyright (C) 2010-2011 x264 project
3 *
4 * Authors: Steven Walters <kemuri9@gmail.com>
5 *          Pegasys Inc. <http://www.pegasys-inc.com>
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24/**
25 * @file
26 * w32threads to pthreads wrapper
27 */
28
29#ifndef FFMPEG_COMPAT_W32PTHREADS_H
30#define FFMPEG_COMPAT_W32PTHREADS_H
31
32/* Build up a pthread-like API using underlying Windows API. Have only static
33 * methods so as to not conflict with a potentially linked in pthread-win32
34 * library.
35 * As most functions here are used without checking return values,
36 * only implement return values as necessary. */
37
38#define WIN32_LEAN_AND_MEAN
39#include <windows.h>
40#include <process.h>
41
42#include "libavutil/common.h"
43#include "libavutil/internal.h"
44#include "libavutil/mem.h"
45
46typedef struct pthread_t {
47    void *handle;
48    void *(*func)(void* arg);
49    void *arg;
50    void *ret;
51} pthread_t;
52
53/* the conditional variable api for windows 6.0+ uses critical sections and
54 * not mutexes */
55typedef CRITICAL_SECTION pthread_mutex_t;
56
57/* This is the CONDITIONAL_VARIABLE typedef for using Window's native
58 * conditional variables on kernels 6.0+.
59 * MinGW does not currently have this typedef. */
60typedef struct pthread_cond_t {
61    void *ptr;
62} pthread_cond_t;
63
64/* function pointers to conditional variable API on windows 6.0+ kernels */
65#if _WIN32_WINNT < 0x0600
66static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
67static void (WINAPI *cond_init)(pthread_cond_t *cond);
68static void (WINAPI *cond_signal)(pthread_cond_t *cond);
69static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
70                                DWORD milliseconds);
71#else
72#define cond_init      InitializeConditionVariable
73#define cond_broadcast WakeAllConditionVariable
74#define cond_signal    WakeConditionVariable
75#define cond_wait      SleepConditionVariableCS
76#endif
77
78static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
79{
80    pthread_t *h = arg;
81    h->ret = h->func(h->arg);
82    return 0;
83}
84
85static int pthread_create(pthread_t *thread, const void *unused_attr,
86                          void *(*start_routine)(void*), void *arg)
87{
88    thread->func   = start_routine;
89    thread->arg    = arg;
90    thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
91                                           0, NULL);
92    return !thread->handle;
93}
94
95static void pthread_join(pthread_t thread, void **value_ptr)
96{
97    DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
98    if (ret != WAIT_OBJECT_0)
99        return;
100    if (value_ptr)
101        *value_ptr = thread.ret;
102    CloseHandle(thread.handle);
103}
104
105static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
106{
107    InitializeCriticalSection(m);
108    return 0;
109}
110static inline int pthread_mutex_destroy(pthread_mutex_t *m)
111{
112    DeleteCriticalSection(m);
113    return 0;
114}
115static inline int pthread_mutex_lock(pthread_mutex_t *m)
116{
117    EnterCriticalSection(m);
118    return 0;
119}
120static inline int pthread_mutex_unlock(pthread_mutex_t *m)
121{
122    LeaveCriticalSection(m);
123    return 0;
124}
125
126/* for pre-Windows 6.0 platforms we need to define and use our own condition
127 * variable and api */
128typedef struct  win32_cond_t {
129    pthread_mutex_t mtx_broadcast;
130    pthread_mutex_t mtx_waiter_count;
131    volatile int waiter_count;
132    HANDLE semaphore;
133    HANDLE waiters_done;
134    volatile int is_broadcast;
135} win32_cond_t;
136
137static int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
138{
139    win32_cond_t *win32_cond = NULL;
140    if (cond_init) {
141        cond_init(cond);
142        return 0;
143    }
144
145    /* non native condition variables */
146    win32_cond = av_mallocz(sizeof(win32_cond_t));
147    if (!win32_cond)
148        return ENOMEM;
149    cond->ptr = win32_cond;
150    win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
151    if (!win32_cond->semaphore)
152        return ENOMEM;
153    win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
154    if (!win32_cond->waiters_done)
155        return ENOMEM;
156
157    pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
158    pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
159    return 0;
160}
161
162static void pthread_cond_destroy(pthread_cond_t *cond)
163{
164    win32_cond_t *win32_cond = cond->ptr;
165    /* native condition variables do not destroy */
166    if (cond_init)
167        return;
168
169    /* non native condition variables */
170    CloseHandle(win32_cond->semaphore);
171    CloseHandle(win32_cond->waiters_done);
172    pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
173    pthread_mutex_destroy(&win32_cond->mtx_broadcast);
174    av_freep(&win32_cond);
175    cond->ptr = NULL;
176}
177
178static void pthread_cond_broadcast(pthread_cond_t *cond)
179{
180    win32_cond_t *win32_cond = cond->ptr;
181    int have_waiter;
182
183    if (cond_broadcast) {
184        cond_broadcast(cond);
185        return;
186    }
187
188    /* non native condition variables */
189    pthread_mutex_lock(&win32_cond->mtx_broadcast);
190    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
191    have_waiter = 0;
192
193    if (win32_cond->waiter_count) {
194        win32_cond->is_broadcast = 1;
195        have_waiter = 1;
196    }
197
198    if (have_waiter) {
199        ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
200        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
201        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
202        ResetEvent(win32_cond->waiters_done);
203        win32_cond->is_broadcast = 0;
204    } else
205        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
206    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
207}
208
209static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
210{
211    win32_cond_t *win32_cond = cond->ptr;
212    int last_waiter;
213    if (cond_wait) {
214        cond_wait(cond, mutex, INFINITE);
215        return 0;
216    }
217
218    /* non native condition variables */
219    pthread_mutex_lock(&win32_cond->mtx_broadcast);
220    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
221    win32_cond->waiter_count++;
222    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
223    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
224
225    // unlock the external mutex
226    pthread_mutex_unlock(mutex);
227    WaitForSingleObject(win32_cond->semaphore, INFINITE);
228
229    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
230    win32_cond->waiter_count--;
231    last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
232    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
233
234    if (last_waiter)
235        SetEvent(win32_cond->waiters_done);
236
237    // lock the external mutex
238    return pthread_mutex_lock(mutex);
239}
240
241static void pthread_cond_signal(pthread_cond_t *cond)
242{
243    win32_cond_t *win32_cond = cond->ptr;
244    int have_waiter;
245    if (cond_signal) {
246        cond_signal(cond);
247        return;
248    }
249
250    pthread_mutex_lock(&win32_cond->mtx_broadcast);
251
252    /* non-native condition variables */
253    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
254    have_waiter = win32_cond->waiter_count;
255    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
256
257    if (have_waiter) {
258        ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
259        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
260        ResetEvent(win32_cond->waiters_done);
261    }
262
263    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
264}
265
266static void w32thread_init(void)
267{
268#if _WIN32_WINNT < 0x0600
269    HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
270    /* if one is available, then they should all be available */
271    cond_init      =
272        (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
273    cond_broadcast =
274        (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
275    cond_signal    =
276        (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
277    cond_wait      =
278        (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
279#endif
280
281}
282
283#endif /* FFMPEG_COMPAT_W32PTHREADS_H */
284