SDL  2.0
SDL_sysmutex.c
Go to the documentation of this file.
1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 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 /* Mutex functions using the Win32 API */
26 
27 #include "../../core/windows/SDL_windows.h"
28 
29 #include "SDL_mutex.h"
30 
31 
32 struct SDL_mutex
33 {
34  CRITICAL_SECTION cs;
35 };
36 
37 /* Create a mutex */
38 SDL_mutex *
39 SDL_CreateMutex(void)
40 {
42 
43  /* Allocate mutex memory */
44  mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
45  if (mutex) {
46  /* Initialize */
47  /* On SMP systems, a non-zero spin count generally helps performance */
48 #if __WINRT__
49  InitializeCriticalSectionEx(&mutex->cs, 2000, 0);
50 #else
51  InitializeCriticalSectionAndSpinCount(&mutex->cs, 2000);
52 #endif
53  } else {
55  }
56  return (mutex);
57 }
58 
59 /* Free the mutex */
60 void
62 {
63  if (mutex) {
64  DeleteCriticalSection(&mutex->cs);
65  SDL_free(mutex);
66  }
67 }
68 
69 /* Lock the mutex */
70 int
71 SDL_LockMutex(SDL_mutex * mutex)
72 {
73  if (mutex == NULL) {
74  return SDL_SetError("Passed a NULL mutex");
75  }
76 
77  EnterCriticalSection(&mutex->cs);
78  return (0);
79 }
80 
81 /* TryLock the mutex */
82 int
84 {
85  int retval = 0;
86  if (mutex == NULL) {
87  return SDL_SetError("Passed a NULL mutex");
88  }
89 
90  if (TryEnterCriticalSection(&mutex->cs) == 0) {
91  retval = SDL_MUTEX_TIMEDOUT;
92  }
93  return retval;
94 }
95 
96 /* Unlock the mutex */
97 int
99 {
100  if (mutex == NULL) {
101  return SDL_SetError("Passed a NULL mutex");
102  }
103 
104  LeaveCriticalSection(&mutex->cs);
105  return (0);
106 }
107 
108 #endif /* SDL_THREAD_WINDOWS */
109 
110 /* vi: set ts=4 sw=4 expandtab: */
int SDL_TryLockMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:103
int SDL_LockMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:73
static SDL_mutex * mutex
Definition: testlock.c:23
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
SDL_bool retval
void SDL_DestroyMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:61
#define SDL_free
int SDL_UnlockMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:159
SDL_mutex * SDL_CreateMutex(void)
Definition: SDL_sysmutex.c:38
#define NULL
Definition: begin_code.h:164
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
#define SDL_SetError
#define SDL_malloc