| /* |
| Simple DirectMedia Layer |
| Copyright (C) 1997-2021 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" |
| |
| /* An implementation of semaphores using mutexes and condition variables */ |
| |
| #include "SDL_timer.h" |
| #include "SDL_thread.h" |
| #include "SDL_systhread_c.h" |
| |
| |
| #if SDL_THREADS_DISABLED |
| |
| SDL_sem * |
| SDL_CreateSemaphore(Uint32 initial_value) |
| { |
| SDL_SetError("SDL not built with thread support"); |
| return (SDL_sem *) 0; |
| } |
| |
| void |
| SDL_DestroySemaphore(SDL_sem * sem) |
| { |
| } |
| |
| int |
| SDL_SemTryWait(SDL_sem * sem) |
| { |
| return SDL_SetError("SDL not built with thread support"); |
| } |
| |
| int |
| SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout) |
| { |
| return SDL_SetError("SDL not built with thread support"); |
| } |
| |
| int |
| SDL_SemWait(SDL_sem * sem) |
| { |
| return SDL_SetError("SDL not built with thread support"); |
| } |
| |
| Uint32 |
| SDL_SemValue(SDL_sem * sem) |
| { |
| return 0; |
| } |
| |
| int |
| SDL_SemPost(SDL_sem * sem) |
| { |
| return SDL_SetError("SDL not built with thread support"); |
| } |
| |
| #else |
| |
| struct SDL_semaphore |
| { |
| Uint32 count; |
| Uint32 waiters_count; |
| SDL_mutex *count_lock; |
| SDL_cond *count_nonzero; |
| }; |
| |
| SDL_sem * |
| SDL_CreateSemaphore(Uint32 initial_value) |
| { |
| SDL_sem *sem; |
| |
| sem = (SDL_sem *) SDL_malloc(sizeof(*sem)); |
| if (!sem) { |
| SDL_OutOfMemory(); |
| return NULL; |
| } |
| sem->count = initial_value; |
| sem->waiters_count = 0; |
| |
| sem->count_lock = SDL_CreateMutex(); |
| sem->count_nonzero = SDL_CreateCond(); |
| if (!sem->count_lock || !sem->count_nonzero) { |
| SDL_DestroySemaphore(sem); |
| return NULL; |
| } |
| |
| return sem; |
| } |
| |
| /* WARNING: |
| You cannot call this function when another thread is using the semaphore. |
| */ |
| void |
| SDL_DestroySemaphore(SDL_sem * sem) |
| { |
| if (sem) { |
| sem->count = 0xFFFFFFFF; |
| while (sem->waiters_count > 0) { |
| SDL_CondSignal(sem->count_nonzero); |
| SDL_Delay(10); |
| } |
| SDL_DestroyCond(sem->count_nonzero); |
| if (sem->count_lock) { |
| SDL_LockMutex(sem->count_lock); |
| SDL_UnlockMutex(sem->count_lock); |
| SDL_DestroyMutex(sem->count_lock); |
| } |
| SDL_free(sem); |
| } |
| } |
| |
| int |
| SDL_SemTryWait(SDL_sem * sem) |
| { |
| int retval; |
| |
| if (!sem) { |
| return SDL_SetError("Passed a NULL semaphore"); |
| } |
| |
| retval = SDL_MUTEX_TIMEDOUT; |
| SDL_LockMutex(sem->count_lock); |
| if (sem->count > 0) { |
| --sem->count; |
| retval = 0; |
| } |
| SDL_UnlockMutex(sem->count_lock); |
| |
| return retval; |
| } |
| |
| int |
| SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout) |
| { |
| int retval; |
| |
| if (!sem) { |
| return SDL_SetError("Passed a NULL semaphore"); |
| } |
| |
| /* A timeout of 0 is an easy case */ |
| if (timeout == 0) { |
| return SDL_SemTryWait(sem); |
| } |
| |
| SDL_LockMutex(sem->count_lock); |
| ++sem->waiters_count; |
| retval = 0; |
| while ((sem->count == 0) && (retval != SDL_MUTEX_TIMEDOUT)) { |
| retval = SDL_CondWaitTimeout(sem->count_nonzero, |
| sem->count_lock, timeout); |
| } |
| --sem->waiters_count; |
| if (retval == 0) { |
| --sem->count; |
| } |
| SDL_UnlockMutex(sem->count_lock); |
| |
| return retval; |
| } |
| |
| int |
| SDL_SemWait(SDL_sem * sem) |
| { |
| return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT); |
| } |
| |
| Uint32 |
| SDL_SemValue(SDL_sem * sem) |
| { |
| Uint32 value; |
| |
| value = 0; |
| if (sem) { |
| SDL_LockMutex(sem->count_lock); |
| value = sem->count; |
| SDL_UnlockMutex(sem->count_lock); |
| } |
| return value; |
| } |
| |
| int |
| SDL_SemPost(SDL_sem * sem) |
| { |
| if (!sem) { |
| return SDL_SetError("Passed a NULL semaphore"); |
| } |
| |
| SDL_LockMutex(sem->count_lock); |
| if (sem->waiters_count > 0) { |
| SDL_CondSignal(sem->count_nonzero); |
| } |
| ++sem->count; |
| SDL_UnlockMutex(sem->count_lock); |
| |
| return 0; |
| } |
| |
| #endif /* SDL_THREADS_DISABLED */ |
| /* vi: set ts=4 sw=4 expandtab: */ |