src/thread/dc/SDL_syssem.c

/*
    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 "SDL_config.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 configured with thread support");
    return (SDL_sem *) 0;
}

void
SDL_DestroySemaphore (SDL_sem * sem)
{
    return;
}

int
SDL_SemTryWait (SDL_sem * sem)
{
    SDL_SetError ("SDL not configured with thread support");
    return -1;
}

int
SDL_SemWaitTimeout (SDL_sem * sem, Uint32 timeout)
{
    SDL_SetError ("SDL not configured with thread support");
    return -1;
}

int
SDL_SemWait (SDL_sem * sem)
{
    SDL_SetError ("SDL not configured with thread support");
    return -1;
}

Uint32
SDL_SemValue (SDL_sem * sem)
{
    return 0;
}

int
SDL_SemPost (SDL_sem * sem)
{
    SDL_SetError ("SDL not configured with thread support");
    return -1;
}

#else

#include <kos/sem.h>

struct SDL_semaphore
{
    semaphore_t sem;
};

SDL_sem *
SDL_CreateSemaphore (Uint32 initial_value)
{
    return (SDL_sem *) sem_create (initial_value);
}

/* WARNING:
   You cannot call this function when another thread is using the semaphore.
*/
void
SDL_DestroySemaphore (SDL_sem * sem)
{
    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return;
    }

    sem_destroy (&sem->sem);
}

int
SDL_SemTryWait (SDL_sem * sem)
{
    int retval;

    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return -1;
    }

    retval = sem_trywait (&sem->sem);
    if (retval == 0)
        return 0;
    else
        return SDL_MUTEX_TIMEDOUT;

    return retval;
}

int
SDL_SemWaitTimeout (SDL_sem * sem, Uint32 timeout)
{
    int retval;

    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return -1;
    }

    /* A timeout of 0 is an easy case */
    if (timeout == 0) {
        return SDL_SemTryWait (sem);
    }

    retval = sem_wait_timed (&sem->sem, timeout);
    if (retval == -1)
        retval = SDL_MUTEX_TIMEDOUT;

    return retval;
}

int
SDL_SemWait (SDL_sem * sem)
{
    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return -1;
    }

    sem_wait (&sem->sem);
    return 0;
}

Uint32
SDL_SemValue (SDL_sem * sem)
{
    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return -1;
    }

    return sem_count (&sem->sem);
}

int
SDL_SemPost (SDL_sem * sem)
{
    if (!sem) {
        SDL_SetError ("Passed a NULL semaphore");
        return -1;
    }

    sem_signal (&sem->sem);
    return 0;
}

#endif /* SDL_THREADS_DISABLED */
/* vi: set ts=4 sw=4 expandtab: */