SDL 2.0
SDL_sysmutex.c File Reference
#include "../../SDL_internal.h"
#include "SDL_thread.h"
#include "SDL_systhread_c.h"
+ Include dependency graph for SDL_sysmutex.c:

Go to the source code of this file.

Data Structures

struct  SDL_mutex
 

Functions

SDL_mutexSDL_CreateMutex (void)
 
void SDL_DestroyMutex (SDL_mutex *mutex)
 
int SDL_LockMutex (SDL_mutex *mutex)
 
int SDL_TryLockMutex (SDL_mutex *mutex)
 
int SDL_mutexV (SDL_mutex *mutex)
 

Function Documentation

◆ SDL_CreateMutex()

SDL_mutex * SDL_CreateMutex ( void  )

Create a mutex, initialized unlocked.

Definition at line 38 of file SDL_sysmutex.c.

39{
41
42 /* Allocate mutex memory */
43 mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
44 if (mutex) {
45 /* Create the mutex semaphore, with initial value 1 */
47 mutex->recursive = 0;
48 mutex->owner = 0;
49 if (!mutex->sem) {
51 mutex = NULL;
52 }
53 } else {
55 }
56 return mutex;
57}
#define SDL_malloc
#define SDL_free
#define SDL_CreateSemaphore
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
#define NULL
Definition: begin_code.h:167
SDL_threadID owner
Definition: SDL_sysmutex.c:32
int recursive
Definition: SDL_sysmutex.c:31
SDL_sem * sem
Definition: SDL_sysmutex.c:33
static SDL_mutex * mutex
Definition: testlock.c:23

◆ SDL_DestroyMutex()

void SDL_DestroyMutex ( SDL_mutex mutex)

Destroy a mutex.

Definition at line 61 of file SDL_sysmutex.c.

62{
63 if (mutex) {
64 if (mutex->sem) {
66 }
68 }
69}
#define SDL_DestroySemaphore

◆ SDL_LockMutex()

int SDL_LockMutex ( SDL_mutex mutex)

Definition at line 73 of file SDL_sysmutex.c.

74{
75#if SDL_THREADS_DISABLED
76 return 0;
77#else
78 SDL_threadID this_thread;
79
80 if (mutex == NULL) {
81 return SDL_SetError("Passed a NULL mutex");
82 }
83
84 this_thread = SDL_ThreadID();
85 if (mutex->owner == this_thread) {
87 } else {
88 /* The order of operations is important.
89 We set the locking thread id after we obtain the lock
90 so unlocks from other threads will fail.
91 */
93 mutex->owner = this_thread;
94 mutex->recursive = 0;
95 }
96
97 return 0;
98#endif /* SDL_THREADS_DISABLED */
99}
#define SDL_SetError
#define SDL_SemWait
#define SDL_ThreadID
unsigned long SDL_threadID
Definition: SDL_thread.h:49

◆ SDL_mutexV()

int SDL_mutexV ( SDL_mutex mutex)

Definition at line 136 of file SDL_sysmutex.c.

137{
138#if SDL_THREADS_DISABLED
139 return 0;
140#else
141 if (mutex == NULL) {
142 return SDL_SetError("Passed a NULL mutex");
143 }
144
145 /* If we don't own the mutex, we can't unlock it */
146 if (SDL_ThreadID() != mutex->owner) {
147 return SDL_SetError("mutex not owned by this thread");
148 }
149
150 if (mutex->recursive) {
151 --mutex->recursive;
152 } else {
153 /* The order of operations is important.
154 First reset the owner so another thread doesn't lock
155 the mutex and set the ownership before we reset it,
156 then release the lock semaphore.
157 */
158 mutex->owner = 0;
160 }
161 return 0;
162#endif /* SDL_THREADS_DISABLED */
163}
#define SDL_SemPost

References mutex, NULL, SDL_mutex::owner, SDL_mutex::recursive, SDL_SemPost, SDL_SetError, SDL_ThreadID, and SDL_mutex::sem.

◆ SDL_TryLockMutex()

int SDL_TryLockMutex ( SDL_mutex mutex)

Try to lock the mutex

Returns
0, SDL_MUTEX_TIMEDOUT, or -1 on error

Definition at line 103 of file SDL_sysmutex.c.

104{
105#if SDL_THREADS_DISABLED
106 return 0;
107#else
108 int retval = 0;
109 SDL_threadID this_thread;
110
111 if (mutex == NULL) {
112 return SDL_SetError("Passed a NULL mutex");
113 }
114
115 this_thread = SDL_ThreadID();
116 if (mutex->owner == this_thread) {
117 ++mutex->recursive;
118 } else {
119 /* The order of operations is important.
120 We set the locking thread id after we obtain the lock
121 so unlocks from other threads will fail.
122 */
124 if (retval == 0) {
125 mutex->owner = this_thread;
126 mutex->recursive = 0;
127 }
128 }
129
130 return retval;
131#endif /* SDL_THREADS_DISABLED */
132}
SDL_bool retval