SDL_syssem.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "../../SDL_internal.h"
#if SDL_THREAD_WINDOWS
/* Semaphore functions using the Win32 API */
#include "../../core/windows/SDL_windows.h"
#include "SDL_thread.h"
struct SDL_semaphore
{
HANDLE id;
LONG count;
};
/* Create a semaphore */
SDL_sem *
SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem;
/* Allocate sem memory */
sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
if (sem) {
/* Create the semaphore, with max value 32K */
#if __WINRT__
sem->id = CreateSemaphoreEx(NULL, initial_value, 32 * 1024, NULL, 0, SEMAPHORE_ALL_ACCESS);
#else
sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
#endif
sem->count = initial_value;
if (!sem->id) {
SDL_SetError("Couldn't create semaphore");
SDL_free(sem);
sem = NULL;
}
} else {
SDL_OutOfMemory();
}
return (sem);
}
/* Free the semaphore */
void
SDL_DestroySemaphore(SDL_sem * sem)
{
if (sem) {
if (sem->id) {
CloseHandle(sem->id);
sem->id = 0;
}
SDL_free(sem);
}
}
int
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
{
int retval;
DWORD dwMilliseconds;
if (!sem) {
return SDL_SetError("Passed a NULL sem");
}
if (timeout == SDL_MUTEX_MAXWAIT) {
dwMilliseconds = INFINITE;
} else {
dwMilliseconds = (DWORD) timeout;
}
#if __WINRT__
switch (WaitForSingleObjectEx(sem->id, dwMilliseconds, FALSE)) {
#else
switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
#endif
case WAIT_OBJECT_0:
InterlockedDecrement(&sem->count);
retval = 0;
break;
case WAIT_TIMEOUT:
retval = SDL_MUTEX_TIMEDOUT;
break;
default:
retval = SDL_SetError("WaitForSingleObject() failed");
break;
}
return retval;
}
int
SDL_SemTryWait(SDL_sem * sem)
{
return SDL_SemWaitTimeout(sem, 0);
}
int
SDL_SemWait(SDL_sem * sem)
{
return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
}
/* Returns the current count of the semaphore */
Uint32
SDL_SemValue(SDL_sem * sem)
{
if (!sem) {
SDL_SetError("Passed a NULL sem");
return 0;
}
return (Uint32)sem->count;
}
int
SDL_SemPost(SDL_sem * sem)
{
if (!sem) {
return SDL_SetError("Passed a NULL sem");
}
/* Increase the counter in the first place, because
* after a successful release the semaphore may
* immediately get destroyed by another thread which
* is waiting for this semaphore.
*/
InterlockedIncrement(&sem->count);
if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
InterlockedDecrement(&sem->count); /* restore */
return SDL_SetError("ReleaseSemaphore() failed");
}
return 0;
}
#endif /* SDL_THREAD_WINDOWS */
/* vi: set ts=4 sw=4 expandtab: */
id
GLuint id
Definition: SDL_opengl_glext.h:528
Uint32
uint32_t Uint32
An unsigned 32-bit integer type.
Definition: SDL_stdinc.h:157
SDL_SemPost
int SDL_SemPost(SDL_sem *sem)
Definition: SDL_syssem.c:200
SDL_MUTEX_TIMEDOUT
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
SDL_thread.h
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_MUTEX_MAXWAIT
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
SDL_SemWaitTimeout
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
Definition: SDL_syssem.c:150
SDL_SemTryWait
int SDL_SemTryWait(SDL_sem *sem)
Definition: SDL_syssem.c:130
SDL_SemWait
int SDL_SemWait(SDL_sem *sem)
Definition: SDL_syssem.c:180
SDL_free
void SDL_free(void *mem)
SDL_semaphore
Definition: SDL_syssem.c:76
SDL_semaphore::count
Uint32 count
Definition: SDL_syssem.c:78
NULL
#define NULL
Definition: begin_code.h:143
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_SetError
#define SDL_SetError
Definition: SDL_dynapi_overrides.h:36
SDL_SemValue
Uint32 SDL_SemValue(SDL_sem *sem)
Definition: SDL_syssem.c:186
timeout
GLbitfield GLuint64 timeout
Definition: SDL_opengl_glext.h:1483
SDL_semaphore::sem
sem_t sem
Definition: SDL_syssem.c:44
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:380
FALSE
#define FALSE
Definition: edid-parse.c:32
SDL_DestroySemaphore
void SDL_DestroySemaphore(SDL_sem *sem)
Definition: SDL_syssem.c:111
SDL_CreateSemaphore
SDL_sem * SDL_CreateSemaphore(Uint32 initial_value)
Definition: SDL_syssem.c:85