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 Libav.
8 *
9 * Libav 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 * Libav 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 Libav; 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 AVCODEC_W32PTHREADS_H
30#define AVCODEC_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
42typedef struct {
43    void *handle;
44    void *(*func)(void* arg);
45    void *arg;
46    void *ret;
47} pthread_t;
48
49/* the conditional variable api for windows 6.0+ uses critical sections and
50 * not mutexes */
51typedef CRITICAL_SECTION pthread_mutex_t;
52
53/* This is the CONDITIONAL_VARIABLE typedef for using Window's native
54 * conditional variables on kernels 6.0+.
55 * MinGW does not currently have this typedef. */
56typedef struct {
57    void *ptr;
58} pthread_cond_t;
59
60/* function pointers to conditional variable API on windows 6.0+ kernels */
61static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
62static void (WINAPI *cond_init)(pthread_cond_t *cond);
63static void (WINAPI *cond_signal)(pthread_cond_t *cond);
64static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
65                                DWORD milliseconds);
66
67static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
68{
69    pthread_t *h = arg;
70    h->ret = h->func(h->arg);
71    return 0;
72}
73
74static int pthread_create(pthread_t *thread, const void *unused_attr,
75                          void *(*start_routine)(void*), void *arg)
76{
77    thread->func   = start_routine;
78    thread->arg    = arg;
79    thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
80                                           0, NULL);
81    return !thread->handle;
82}
83
84static void pthread_join(pthread_t thread, void **value_ptr)
85{
86    DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
87    if (ret != WAIT_OBJECT_0)
88        return;
89    if (value_ptr)
90        *value_ptr = thread.ret;
91    CloseHandle(thread.handle);
92}
93
94static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
95{
96    InitializeCriticalSection(m);
97    return 0;
98}
99static inline int pthread_mutex_destroy(pthread_mutex_t *m)
100{
101    DeleteCriticalSection(m);
102    return 0;
103}
104static inline int pthread_mutex_lock(pthread_mutex_t *m)
105{
106    EnterCriticalSection(m);
107    return 0;
108}
109static inline int pthread_mutex_unlock(pthread_mutex_t *m)
110{
111    LeaveCriticalSection(m);
112    return 0;
113}
114
115/* for pre-Windows 6.0 platforms we need to define and use our own condition
116 * variable and api */
117typedef struct {
118    pthread_mutex_t mtx_broadcast;
119    pthread_mutex_t mtx_waiter_count;
120    volatile int waiter_count;
121    HANDLE semaphore;
122    HANDLE waiters_done;
123    volatile int is_broadcast;
124} win32_cond_t;
125
126static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
127{
128    win32_cond_t *win32_cond = NULL;
129    if (cond_init) {
130        cond_init(cond);
131        return;
132    }
133
134    /* non native condition variables */
135    win32_cond = av_mallocz(sizeof(win32_cond_t));
136    if (!win32_cond)
137        return;
138    cond->ptr = win32_cond;
139    win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
140    if (!win32_cond->semaphore)
141        return;
142    win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
143    if (!win32_cond->waiters_done)
144        return;
145
146    pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
147    pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
148}
149
150static void pthread_cond_destroy(pthread_cond_t *cond)
151{
152    win32_cond_t *win32_cond = cond->ptr;
153    /* native condition variables do not destroy */
154    if (cond_init)
155        return;
156
157    /* non native condition variables */
158    CloseHandle(win32_cond->semaphore);
159    CloseHandle(win32_cond->waiters_done);
160    pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
161    pthread_mutex_destroy(&win32_cond->mtx_broadcast);
162    av_freep(&win32_cond);
163    cond->ptr = NULL;
164}
165
166static void pthread_cond_broadcast(pthread_cond_t *cond)
167{
168    win32_cond_t *win32_cond = cond->ptr;
169    int have_waiter;
170
171    if (cond_broadcast) {
172        cond_broadcast(cond);
173        return;
174    }
175
176    /* non native condition variables */
177    pthread_mutex_lock(&win32_cond->mtx_broadcast);
178    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
179    have_waiter = 0;
180
181    if (win32_cond->waiter_count) {
182        win32_cond->is_broadcast = 1;
183        have_waiter = 1;
184    }
185
186    if (have_waiter) {
187        ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
188        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
189        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
190        ResetEvent(win32_cond->waiters_done);
191        win32_cond->is_broadcast = 0;
192    } else
193        pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
194    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
195}
196
197static void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
198{
199    win32_cond_t *win32_cond = cond->ptr;
200    int last_waiter;
201    if (cond_wait) {
202        cond_wait(cond, mutex, INFINITE);
203        return;
204    }
205
206    /* non native condition variables */
207    pthread_mutex_lock(&win32_cond->mtx_broadcast);
208    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
209    win32_cond->waiter_count++;
210    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
211    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
212
213    // unlock the external mutex
214    pthread_mutex_unlock(mutex);
215    WaitForSingleObject(win32_cond->semaphore, INFINITE);
216
217    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
218    win32_cond->waiter_count--;
219    last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
220    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
221
222    if (last_waiter)
223        SetEvent(win32_cond->waiters_done);
224
225    // lock the external mutex
226    return pthread_mutex_lock(mutex);
227}
228
229static void pthread_cond_signal(pthread_cond_t *cond)
230{
231    win32_cond_t *win32_cond = cond->ptr;
232    int have_waiter;
233    if (cond_signal) {
234        cond_signal(cond);
235        return;
236    }
237
238    pthread_mutex_lock(&win32_cond->mtx_broadcast);
239
240    /* non-native condition variables */
241    pthread_mutex_lock(&win32_cond->mtx_waiter_count);
242    have_waiter = win32_cond->waiter_count;
243    pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
244
245    if (have_waiter) {
246        ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
247        WaitForSingleObject(win32_cond->waiters_done, INFINITE);
248        ResetEvent(win32_cond->waiters_done);
249    }
250
251    pthread_mutex_unlock(&win32_cond->mtx_broadcast);
252}
253
254static void w32thread_init(void)
255{
256    HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
257    /* if one is available, then they should all be available */
258    cond_init      =
259        (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
260    cond_broadcast =
261        (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
262    cond_signal    =
263        (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
264    cond_wait      =
265        (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
266}
267
268#endif /* AVCODEC_W32PTHREADS_H */
269