| /* |
| Simple DirectMedia Layer |
| Copyright (C) 1997-2020 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; |
| } |
| switch (WaitForSingleObjectEx(sem->id, dwMilliseconds, FALSE)) { |
| 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: */ |