Atlas - SDL_syssem.c
Home / ext / SDL2 / src / thread / windows
Lines: 1 | Size: 3734 bytes
[Download] [Show on GitHub] [Search similar files] [Raw] [Raw (proxy)] 
[FILE BEGIN]
1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <[email protected]>
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/* Semaphore functions using the Win32 API */
26
27#include "../../core/windows/SDL_windows.h"
28
29#include "SDL_thread.h"
30
31struct SDL_semaphore
32{
33    HANDLE id;
34    LONG count;
35};
36
37
38/* Create a semaphore */
39SDL_sem *
40SDL_CreateSemaphore(Uint32 initial_value)
41{
42    SDL_sem *sem;
43
44    /* Allocate sem memory */
45    sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
46    if (sem) {
47        /* Create the semaphore, with max value 32K */
48#if __WINRT__
49        sem->id = CreateSemaphoreEx(NULL, initial_value, 32 * 1024, NULL, 0, SEMAPHORE_ALL_ACCESS);
50#else
51        sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
52#endif
53        sem->count = initial_value;
54        if (!sem->id) {
55            SDL_SetError("Couldn't create semaphore");
56            SDL_free(sem);
57            sem = NULL;
58        }
59    } else {
60        SDL_OutOfMemory();
61    }
62    return (sem);
63}
64
65/* Free the semaphore */
66void
67SDL_DestroySemaphore(SDL_sem * sem)
68{
69    if (sem) {
70        if (sem->id) {
71            CloseHandle(sem->id);
72            sem->id = 0;
73        }
74        SDL_free(sem);
75    }
76}
77
78int
79SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
80{
81    int retval;
82    DWORD dwMilliseconds;
83
84    if (!sem) {
85        return SDL_SetError("Passed a NULL sem");
86    }
87
88    if (timeout == SDL_MUTEX_MAXWAIT) {
89        dwMilliseconds = INFINITE;
90    } else {
91        dwMilliseconds = (DWORD) timeout;
92    }
93    switch (WaitForSingleObjectEx(sem->id, dwMilliseconds, FALSE)) {
94    case WAIT_OBJECT_0:
95        InterlockedDecrement(&sem->count);
96        retval = 0;
97        break;
98    case WAIT_TIMEOUT:
99        retval = SDL_MUTEX_TIMEDOUT;
100        break;
101    default:
102        retval = SDL_SetError("WaitForSingleObject() failed");
103        break;
104    }
105    return retval;
106}
107
108int
109SDL_SemTryWait(SDL_sem * sem)
110{
111    return SDL_SemWaitTimeout(sem, 0);
112}
113
114int
115SDL_SemWait(SDL_sem * sem)
116{
117    return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
118}
119
120/* Returns the current count of the semaphore */
121Uint32
122SDL_SemValue(SDL_sem * sem)
123{
124    if (!sem) {
125        SDL_SetError("Passed a NULL sem");
126        return 0;
127    }
128    return (Uint32)sem->count;
129}
130
131int
132SDL_SemPost(SDL_sem * sem)
133{
134    if (!sem) {
135        return SDL_SetError("Passed a NULL sem");
136    }
137    /* Increase the counter in the first place, because
138     * after a successful release the semaphore may
139     * immediately get destroyed by another thread which
140     * is waiting for this semaphore.
141     */
142    InterlockedIncrement(&sem->count);
143    if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
144        InterlockedDecrement(&sem->count);      /* restore */
145        return SDL_SetError("ReleaseSemaphore() failed");
146    }
147    return 0;
148}
149
150#endif /* SDL_THREAD_WINDOWS */
151
152/* vi: set ts=4 sw=4 expandtab: */
153
[FILE END]
(C) 2025 0x4248
(C) 2025 4248 Media and 4248 Systems, All part of 0x4248
See LICENCE files for more information. Not all files are by 0x4248 always check Licencing.