Hash :
b48e54aa
Author :
Date :
2015-01-26T22:00:29
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148
/*
Simple DirectMedia Layer
Copyright (C) 1997-2014 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 */
sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
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;
}
switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
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: */