SDL
2.0
SDL_syssem.c
Go to the documentation of this file.
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/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "../../SDL_internal.h"
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#if SDL_THREAD_WINDOWS
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/* Semaphore functions using the Win32 API */
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#include "../../core/windows/SDL_windows.h"
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#include "
SDL_thread.h
"
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struct
SDL_semaphore
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{
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HANDLE
id
;
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LONG
count
;
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};
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/* Create a semaphore */
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SDL_sem *
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SDL_CreateSemaphore
(
Uint32
initial_value)
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{
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SDL_sem *
sem
;
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/* Allocate sem memory */
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sem
= (SDL_sem *)
SDL_malloc
(
sizeof
(*
sem
));
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if
(
sem
) {
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/* Create the semaphore, with max value 32K */
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#if __WINRT__
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sem
->id = CreateSemaphoreEx(
NULL
, initial_value, 32 * 1024,
NULL
, 0, SEMAPHORE_ALL_ACCESS);
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#else
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sem
->id = CreateSemaphore(
NULL
, initial_value, 32 * 1024,
NULL
);
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#endif
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sem
->count = initial_value;
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if
(!
sem
->id) {
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SDL_SetError
(
"Couldn't create semaphore"
);
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SDL_free
(
sem
);
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sem
=
NULL
;
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}
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}
else
{
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SDL_OutOfMemory
();
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}
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return
(
sem
);
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}
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/* Free the semaphore */
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void
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SDL_DestroySemaphore
(SDL_sem *
sem
)
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{
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if
(
sem
) {
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if
(
sem
->id) {
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CloseHandle(
sem
->id);
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sem
->id = 0;
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}
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SDL_free
(
sem
);
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}
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}
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int
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SDL_SemWaitTimeout
(SDL_sem *
sem
,
Uint32
timeout
)
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{
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int
retval
;
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DWORD dwMilliseconds;
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if
(!
sem
) {
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return
SDL_SetError
(
"Passed a NULL sem"
);
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}
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if
(
timeout
==
SDL_MUTEX_MAXWAIT
) {
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dwMilliseconds = INFINITE;
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}
else
{
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dwMilliseconds = (DWORD)
timeout
;
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}
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switch
(WaitForSingleObjectEx(
sem
->id, dwMilliseconds,
FALSE
)) {
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case
WAIT_OBJECT_0:
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InterlockedDecrement(&
sem
->count);
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retval
= 0;
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break
;
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case
WAIT_TIMEOUT:
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retval
=
SDL_MUTEX_TIMEDOUT
;
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break
;
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default
:
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retval
=
SDL_SetError
(
"WaitForSingleObject() failed"
);
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break
;
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}
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return
retval
;
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}
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int
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SDL_SemTryWait
(SDL_sem *
sem
)
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{
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return
SDL_SemWaitTimeout
(
sem
, 0);
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}
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int
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SDL_SemWait
(SDL_sem *
sem
)
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{
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return
SDL_SemWaitTimeout
(
sem
,
SDL_MUTEX_MAXWAIT
);
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}
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/* Returns the current count of the semaphore */
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Uint32
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SDL_SemValue
(SDL_sem *
sem
)
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{
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if
(!
sem
) {
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SDL_SetError
(
"Passed a NULL sem"
);
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return
0;
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}
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return
(
Uint32
)
sem
->count;
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}
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int
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SDL_SemPost
(SDL_sem *
sem
)
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{
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if
(!
sem
) {
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return
SDL_SetError
(
"Passed a NULL sem"
);
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}
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/* Increase the counter in the first place, because
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* after a successful release the semaphore may
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* immediately get destroyed by another thread which
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* is waiting for this semaphore.
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*/
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InterlockedIncrement(&
sem
->count);
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if
(ReleaseSemaphore(
sem
->id, 1,
NULL
) ==
FALSE
) {
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InterlockedDecrement(&
sem
->count);
/* restore */
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return
SDL_SetError
(
"ReleaseSemaphore() failed"
);
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}
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return
0;
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}
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#endif
/* SDL_THREAD_WINDOWS */
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/* vi: set ts=4 sw=4 expandtab: */
Uint32
uint32_t Uint32
Definition:
SDL_stdinc.h:203
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:1483
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
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:528
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:76
SDL_malloc
#define SDL_malloc
Definition:
SDL_dynapi_overrides.h:374
FALSE
#define FALSE
Definition:
edid-parse.c:34
src
thread
windows
SDL_syssem.c
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