Mercurial > sdl-ios-xcode
diff src/thread/pthread/SDL_syssem.c @ 1361:19418e4422cb
New configure-based build system. Still work in progress, but much improved
author | Sam Lantinga <slouken@libsdl.org> |
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date | Thu, 16 Feb 2006 10:11:48 +0000 |
parents | |
children | d910939febfa |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/thread/pthread/SDL_syssem.c Thu Feb 16 10:11:48 2006 +0000 @@ -0,0 +1,174 @@ +/* + SDL - Simple DirectMedia Layer + Copyright (C) 1997-2006 Sam Lantinga + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + + Sam Lantinga + slouken@libsdl.org +*/ + +#include <pthread.h> +#include <semaphore.h> + +#include "SDL_thread.h" +#include "SDL_timer.h" + +/* Wrapper around POSIX 1003.1b semaphores */ + +#if MACOSX +#define USE_NAMED_SEMAPHORES 1 +#endif /* MACOSX */ + +struct SDL_semaphore { + sem_t *sem; +#if !USE_NAMED_SEMAPHORES + sem_t sem_data; +#endif +}; + +/* Create a semaphore, initialized with value */ +SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) +{ + SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem)); + if ( sem ) { +#if USE_NAMED_SEMAPHORES + static int semnum = 0; + char name[32]; + + SDL_snprintf(name, SDL_arraysize(name), "/SDL_sem-%d-%4.4d", getpid(), semnum++); + sem->sem = sem_open(name, O_CREAT, 0600, initial_value); + if ( sem->sem == (sem_t *)SEM_FAILED ) { + SDL_SetError("sem_open(%s) failed", name); + SDL_free(sem); + sem = NULL; + } else { + sem_unlink(name); + } +#else + if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) { + SDL_SetError("sem_init() failed"); + SDL_free(sem); + sem = NULL; + } else { + sem->sem = &sem->sem_data; + } +#endif /* USE_NAMED_SEMAPHORES */ + } else { + SDL_OutOfMemory(); + } + return sem; +} + +void SDL_DestroySemaphore(SDL_sem *sem) +{ + if ( sem ) { +#if USE_NAMED_SEMAPHORES + sem_close(sem->sem); +#else + sem_destroy(sem->sem); +#endif + SDL_free(sem); + } +} + +int SDL_SemTryWait(SDL_sem *sem) +{ + int retval; + + if ( ! sem ) { + SDL_SetError("Passed a NULL semaphore"); + return -1; + } + retval = SDL_MUTEX_TIMEDOUT; + if ( sem_trywait(sem->sem) == 0 ) { + retval = 0; + } + return retval; +} + +int SDL_SemWait(SDL_sem *sem) +{ + int retval; + + if ( ! sem ) { + SDL_SetError("Passed a NULL semaphore"); + return -1; + } + + retval = sem_wait(sem->sem); + if ( retval < 0 ) { + SDL_SetError("sem_wait() failed"); + } + return retval; +} + +int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) +{ + int retval; + + if ( ! sem ) { + SDL_SetError("Passed a NULL semaphore"); + return -1; + } + + /* Try the easy cases first */ + if ( timeout == 0 ) { + return SDL_SemTryWait(sem); + } + if ( timeout == SDL_MUTEX_MAXWAIT ) { + return SDL_SemWait(sem); + } + + /* Ack! We have to busy wait... */ + timeout += SDL_GetTicks(); + do { + retval = SDL_SemTryWait(sem); + if ( retval == 0 ) { + break; + } + SDL_Delay(1); + } while ( SDL_GetTicks() < timeout ); + + return retval; +} + +Uint32 SDL_SemValue(SDL_sem *sem) +{ + int ret = 0; + if ( sem ) { + sem_getvalue(sem->sem, &ret); + if ( ret < 0 ) { + ret = 0; + } + } + return (Uint32)ret; +} + +int SDL_SemPost(SDL_sem *sem) +{ + int retval; + + if ( ! sem ) { + SDL_SetError("Passed a NULL semaphore"); + return -1; + } + + retval = sem_post(sem->sem); + if ( retval < 0 ) { + SDL_SetError("sem_post() failed"); + } + return retval; +}