xnu-792.12.6.tar.gz

[apple/xnu.git] / iokit / Kernel / IOSyncer.cpp

/*
 * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code 
 * as defined in and that are subject to the Apple Public Source License 
 * Version 2.0 (the 'License'). You may not use this file except in 
 * compliance with the License.  The rights granted to you under the 
 * License may not be used to create, or enable the creation or 
 * redistribution of, unlawful or unlicensed copies of an Apple operating 
 * system, or to circumvent, violate, or enable the circumvention or 
 * violation of, any terms of an Apple operating system software license 
 * agreement.
 *
 * Please obtain a copy of the License at 
 * http://www.opensource.apple.com/apsl/ and read it before using this 
 * file.
 *
 * The Original Code and all software distributed under the License are 
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 
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/* IOSyncer.cpp created by wgulland on 2000-02-02 */

#include <IOKit/IOLib.h>
#include <IOKit/IOSyncer.h>

OSDefineMetaClassAndStructors(IOSyncer, OSObject)

IOSyncer * IOSyncer::create(bool twoRetains)
{
    IOSyncer * me = new IOSyncer;

    if (me && !me->init(twoRetains)) {
        me->release();
        return 0;
    }

    return me;
}

bool IOSyncer::init(bool twoRetains)
{
    if (!OSObject::init())
        return false;

    if (!(guardLock = IOSimpleLockAlloc()) )
        return false;
	
    IOSimpleLockInit(guardLock);

    if(twoRetains)
	retain();

    fResult = kIOReturnSuccess;

    reinit();

    return true;
}

void IOSyncer::reinit()
{
    IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);
    threadMustStop = true;
    IOSimpleLockUnlockEnableInterrupt(guardLock, is);
}

void IOSyncer::free()
{
    // just in case a thread is blocked here:
    privateSignal();

    if (guardLock != NULL)
       IOSimpleLockFree(guardLock);

    OSObject::free();
}

IOReturn IOSyncer::wait(bool autoRelease)
{
    IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);

    if (threadMustStop) {
	assert_wait((void *) &threadMustStop, false);
    	IOSimpleLockUnlockEnableInterrupt(guardLock, is);
        thread_block(THREAD_CONTINUE_NULL);
    }
    else
        IOSimpleLockUnlockEnableInterrupt(guardLock, is);

    IOReturn result = fResult;	// Pick up before auto deleting!

    if(autoRelease)
	release();

    return result;
}

void IOSyncer::signal(IOReturn res, bool autoRelease)
{
    fResult = res;
    privateSignal();
    if(autoRelease)
	release();
}

void IOSyncer::privateSignal()
{
    if (threadMustStop) {
         IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);
         threadMustStop = false;
         thread_wakeup_one((void *) &threadMustStop);
         IOSimpleLockUnlockEnableInterrupt(guardLock, is);
    }
}