SDL  2.0
SDL_syssem.c
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "../../SDL_internal.h"
22 
23 #if SDL_THREAD_WINDOWS
24 
25 /* Semaphore functions using the Win32 API */
26 
27 #include "../../core/windows/SDL_windows.h"
28 
29 #include "SDL_thread.h"
30 
31 struct SDL_semaphore
32 {
33  HANDLE id;
34  LONG count;
35 };
36 
37 
38 /* Create a semaphore */
39 SDL_sem *
40 SDL_CreateSemaphore(Uint32 initial_value)
41 {
42  SDL_sem *sem;
43 
44  /* Allocate sem memory */
45  sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
46  if (sem) {
47  /* Create the semaphore, with max value 32K */
48 #if __WINRT__
49  sem->id = CreateSemaphoreEx(NULL, initial_value, 32 * 1024, NULL, 0, SEMAPHORE_ALL_ACCESS);
50 #else
51  sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
52 #endif
53  sem->count = initial_value;
54  if (!sem->id) {
55  SDL_SetError("Couldn't create semaphore");
56  SDL_free(sem);
57  sem = NULL;
58  }
59  } else {
61  }
62  return (sem);
63 }
64 
65 /* Free the semaphore */
66 void
67 SDL_DestroySemaphore(SDL_sem * sem)
68 {
69  if (sem) {
70  if (sem->id) {
71  CloseHandle(sem->id);
72  sem->id = 0;
73  }
74  SDL_free(sem);
75  }
76 }
77 
78 int
79 SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
80 {
81  int retval;
82  DWORD dwMilliseconds;
83 
84  if (!sem) {
85  return SDL_SetError("Passed a NULL sem");
86  }
87 
88  if (timeout == SDL_MUTEX_MAXWAIT) {
89  dwMilliseconds = INFINITE;
90  } else {
91  dwMilliseconds = (DWORD) timeout;
92  }
93 #if __WINRT__
94  switch (WaitForSingleObjectEx(sem->id, dwMilliseconds, FALSE)) {
95 #else
96  switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
97 #endif
98  case WAIT_OBJECT_0:
99  InterlockedDecrement(&sem->count);
100  retval = 0;
101  break;
102  case WAIT_TIMEOUT:
103  retval = SDL_MUTEX_TIMEDOUT;
104  break;
105  default:
106  retval = SDL_SetError("WaitForSingleObject() failed");
107  break;
108  }
109  return retval;
110 }
111 
112 int
113 SDL_SemTryWait(SDL_sem * sem)
114 {
115  return SDL_SemWaitTimeout(sem, 0);
116 }
117 
118 int
119 SDL_SemWait(SDL_sem * sem)
120 {
122 }
123 
124 /* Returns the current count of the semaphore */
125 Uint32
126 SDL_SemValue(SDL_sem * sem)
127 {
128  if (!sem) {
129  SDL_SetError("Passed a NULL sem");
130  return 0;
131  }
132  return (Uint32)sem->count;
133 }
134 
135 int
136 SDL_SemPost(SDL_sem * sem)
137 {
138  if (!sem) {
139  return SDL_SetError("Passed a NULL sem");
140  }
141  /* Increase the counter in the first place, because
142  * after a successful release the semaphore may
143  * immediately get destroyed by another thread which
144  * is waiting for this semaphore.
145  */
146  InterlockedIncrement(&sem->count);
147  if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
148  InterlockedDecrement(&sem->count); /* restore */
149  return SDL_SetError("ReleaseSemaphore() failed");
150  }
151  return 0;
152 }
153 
154 #endif /* SDL_THREAD_WINDOWS */
155 
156 /* vi: set ts=4 sw=4 expandtab: */
GLuint id
uint32_t Uint32
An unsigned 32-bit integer type.
Definition: SDL_stdinc.h:169
int SDL_SemPost(SDL_sem *sem)
Definition: SDL_syssem.c:200
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
SDL_bool retval
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
Definition: SDL_syssem.c:150
int SDL_SemTryWait(SDL_sem *sem)
Definition: SDL_syssem.c:130
int SDL_SemWait(SDL_sem *sem)
Definition: SDL_syssem.c:180
void SDL_free(void *mem)
Uint32 count
Definition: SDL_syssem.c:78
#define NULL
Definition: begin_code.h:164
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
#define SDL_SetError
Uint32 SDL_SemValue(SDL_sem *sem)
Definition: SDL_syssem.c:186
GLbitfield GLuint64 timeout
#define SDL_malloc
#define FALSE
Definition: edid-parse.c:34
void SDL_DestroySemaphore(SDL_sem *sem)
Definition: SDL_syssem.c:111
SDL_sem * SDL_CreateSemaphore(Uint32 initial_value)
Definition: SDL_syssem.c:85