/*
 * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_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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 */

#ifndef _IOSUBMEMORYDESCRIPTOR_H
#define _IOSUBMEMORYDESCRIPTOR_H

#include <IOKit/IOMemoryDescriptor.h>

/*! @class IOSubMemoryDescriptor : public IOMemoryDescriptor
    @abstract The IOSubMemoryDescriptor object describes a memory area made up of a portion of another IOMemoryDescriptor.
    @discussion The IOSubMemoryDescriptor object represents a subrange of memory, specified as a portion of another IOMemoryDescriptor. */

class IOSubMemoryDescriptor : public IOMemoryDescriptor
{
    OSDeclareDefaultStructors(IOSubMemoryDescriptor);

protected:
    IOMemoryDescriptor * _parent;
    IOByteCount 	 _start;

    virtual void free();

public:
/*! @function withSubRange
    @abstract Create an IOMemoryDescriptor to describe a subrange of an existing descriptor.
    @discussion  This method creates and initializes an IOMemoryDescriptor for memory consisting of a subrange of the specified memory descriptor. The parent memory descriptor is retained by the new descriptor.
    @param of The parent IOMemoryDescriptor of which a subrange is to be used for the new descriptor, which will be retained by the subrange IOMemoryDescriptor.
    @param offset A byte offset into the parent memory descriptor's memory.
    @param length The length of the subrange.
    @param options
        kIOMemoryDirectionMask (options:direction)	This nibble indicates the I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures. 
    @result The created IOMemoryDescriptor on success, to be released by the caller, or zero on failure. */

    static IOSubMemoryDescriptor *	withSubRange(IOMemoryDescriptor *of,
					     IOByteCount offset,
					     IOByteCount length,
					     IOOptionBits options);

    /*
     * Initialize or reinitialize an IOSubMemoryDescriptor to describe
     * a subrange of an existing descriptor.
     *
     * An IOSubMemoryDescriptor can be re-used by calling initSubRange
     * again on an existing instance -- note that this behavior is not
     * commonly supported in other IOKit classes, although it is here.
     */
    virtual bool initSubRange( IOMemoryDescriptor * parent,
				IOByteCount offset, IOByteCount length,
				IODirection withDirection );

    /*
     * IOMemoryDescriptor required methods
     */

    virtual addr64_t getPhysicalSegment( IOByteCount   offset,
                                         IOByteCount * length,
                                         IOOptionBits  options = 0 );

    virtual IOReturn prepare(IODirection forDirection = kIODirectionNone);

    virtual IOReturn complete(IODirection forDirection = kIODirectionNone);

#ifdef __LP64__
    virtual
#endif /* __LP64__ */
    IOReturn redirect( task_t safeTask, bool redirect );

    virtual IOReturn setPurgeable( IOOptionBits newState,
                                    IOOptionBits * oldState );

    // support map() on kIOMemoryTypeVirtual without prepare()
    virtual IOMemoryMap * 	makeMapping(
	IOMemoryDescriptor *	owner,
	task_t			intoTask,
	IOVirtualAddress	atAddress,
	IOOptionBits		options,
	IOByteCount		offset,
	IOByteCount		length );

	virtual uint64_t getPreparationID( void );

};

#endif /* !_IOSUBMEMORYDESCRIPTOR_H */