SDL  2.0
SDL_syssem.c
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2020 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
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  switch (WaitForSingleObjectEx(sem->id, dwMilliseconds, FALSE)) {
94  case WAIT_OBJECT_0:
95  InterlockedDecrement(&sem->count);
96  retval = 0;
97  break;
98  case WAIT_TIMEOUT:
100  break;
101  default:
102  retval = SDL_SetError("WaitForSingleObject() failed");
103  break;
104  }
105  return retval;
106 }
107 
108 int
109 SDL_SemTryWait(SDL_sem * sem)
110 {
111  return SDL_SemWaitTimeout(sem, 0);
112 }
113 
114 int
115 SDL_SemWait(SDL_sem * sem)
116 {
118 }
119 
120 /* Returns the current count of the semaphore */
121 Uint32
122 SDL_SemValue(SDL_sem * sem)
123 {
124  if (!sem) {
125  SDL_SetError("Passed a NULL sem");
126  return 0;
127  }
128  return (Uint32)sem->count;
129 }
130 
131 int
132 SDL_SemPost(SDL_sem * sem)
133 {
134  if (!sem) {
135  return SDL_SetError("Passed a NULL sem");
136  }
137  /* Increase the counter in the first place, because
138  * after a successful release the semaphore may
139  * immediately get destroyed by another thread which
140  * is waiting for this semaphore.
141  */
142  InterlockedIncrement(&sem->count);
143  if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
144  InterlockedDecrement(&sem->count); /* restore */
145  return SDL_SetError("ReleaseSemaphore() failed");
146  }
147  return 0;
148 }
149 
150 #endif /* SDL_THREAD_WINDOWS */
151 
152 /* vi: set ts=4 sw=4 expandtab: */
SDL_SemTryWait
int SDL_SemTryWait(SDL_sem *sem)
Definition: SDL_syssem.c:130
NULL
#define NULL
Definition: begin_code.h:167
timeout
GLbitfield GLuint64 timeout
Definition: SDL_opengl_glext.h:1486
sem
static SDL_sem * sem
Definition: testsem.c:23
SDL_CreateSemaphore
SDL_sem * SDL_CreateSemaphore(Uint32 initial_value)
Definition: SDL_syssem.c:85
SDL_SemWait
int SDL_SemWait(SDL_sem *sem)
Definition: SDL_syssem.c:180
Uint32
uint32_t Uint32
Definition: SDL_stdinc.h:203
SDL_MUTEX_TIMEDOUT
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
SDL_thread.h
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_free
#define SDL_free
Definition: SDL_dynapi_overrides.h:377
SDL_MUTEX_MAXWAIT
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
SDL_SemPost
int SDL_SemPost(SDL_sem *sem)
Definition: SDL_syssem.c:200
SDL_semaphore::count
Uint32 count
Definition: SDL_syssem.c:78
SDL_SemValue
Uint32 SDL_SemValue(SDL_sem *sem)
Definition: SDL_syssem.c:186
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
id
GLuint id
Definition: SDL_opengl_glext.h:531
SDL_SetError
#define SDL_SetError
Definition: SDL_dynapi_overrides.h:30
SDL_SemWaitTimeout
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
Definition: SDL_syssem.c:150
SDL_DestroySemaphore
void SDL_DestroySemaphore(SDL_sem *sem)
Definition: SDL_syssem.c:111
SDL_semaphore
Definition: SDL_syssem.c:77
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:374
FALSE
#define FALSE
Definition: edid-parse.c:34