src/thread/win32/SDL_syssem.c
author Ryan C. Gordon <icculus@icculus.org>
Sun, 10 Jan 2010 05:06:03 +0000
changeset 3623 9a73fecd9181
parent 3071 6f3308d4b6cd
child 3697 f7b03b6838cb
permissions -rw-r--r--
Reverted r5460 ... this was merged from 1.2, but was later reverted there.

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 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"

/* Semaphore functions using the Win32 API */

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#include "SDL_thread.h"
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
#include "win_ce_semaphore.h"
#endif


struct SDL_semaphore
{
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    SYNCHHANDLE id;
#else
    HANDLE id;
#endif
    Uint32 volatile 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 defined(_WIN32_WCE) && (_WIN32_WCE < 300)
        sem->id = CreateSemaphoreCE(NULL, initial_value, 32 * 1024, NULL);
#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) {
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
            CloseSynchHandle(sem->id);
#else
            CloseHandle(sem->id);
#endif
            sem->id = 0;
        }
        SDL_free(sem);
    }
}

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

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

    if (timeout == SDL_MUTEX_MAXWAIT) {
        dwMilliseconds = INFINITE;
    } else {
        dwMilliseconds = (DWORD) timeout;
    }
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    switch (WaitForSemaphoreCE(sem->id, dwMilliseconds)) {
#else
    switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
#endif
    case WAIT_OBJECT_0:
        InterlockedDecrement(&sem->count);
        retval = 0;
        break;
    case WAIT_TIMEOUT:
        retval = SDL_MUTEX_TIMEDOUT;
        break;
    default:
        SDL_SetError("WaitForSingleObject() failed");
        retval = -1;
        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 sem->count;
}

int
SDL_SemPost(SDL_sem * sem)
{
    if (!sem) {
        SDL_SetError("Passed a NULL sem");
        return -1;
    }
    /* 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 defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    if (ReleaseSemaphoreCE(sem->id, 1, NULL) == FALSE) {
#else
    if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
#endif
        InterlockedDecrement(&sem->count);      /* restore */
        SDL_SetError("ReleaseSemaphore() failed");
        return -1;
    }
    return 0;
}

/* vi: set ts=4 sw=4 expandtab: */