[apple/xnu.git] / iokit / IOKit / IOBufferMemoryDescriptor.h

/*
 * 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,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#ifndef _IOBUFFERMEMORYDESCRIPTOR_H
#define _IOBUFFERMEMORYDESCRIPTOR_H

#include <IOKit/IOMemoryDescriptor.h>

enum {
    kIOMemoryPhysicallyContiguous	= 0x00000010,
    kIOMemoryPageable	      		= 0x00000020,
    kIOMemoryPurgeable	      		= 0x00000040,
    kIOMemorySharingTypeMask		= 0x000f0000,
    kIOMemoryUnshared			= 0x00000000,
    kIOMemoryKernelUserShared		= 0x00010000,
    // shared IOMemoryDescriptor options for IOBufferMemoryDescriptor:
    kIOBufferDescriptorMemoryFlags	= kIOMemoryDirectionMask 
#ifdef XNU_KERNEL_PRIVATE
					| kIOMemoryAutoPrepare
#endif
					| kIOMemoryThreadSafe
};

#define _IOBUFFERMEMORYDESCRIPTOR_INTASKWITHOPTIONS_	1
/*!
    @class IOBufferMemoryDescriptor
    @abstract Provides a simple memory descriptor that allocates its own buffer memory.
*/

class IOBufferMemoryDescriptor : public IOGeneralMemoryDescriptor
{
    OSDeclareDefaultStructors(IOBufferMemoryDescriptor);

private:
/*! @struct ExpansionData
    @discussion This structure will be used to expand the capablilties of this class in the future.
    */    
    struct ExpansionData {
	IOMemoryMap *   map;
    };

/*! @var reserved
    Reserved for future use.  (Internal use only)  */
    ExpansionData * reserved;

protected:
    void *               _buffer;
    vm_size_t            _capacity;
    vm_offset_t		 _alignment;
    IOOptionBits	 _options;
private:
    uintptr_t		 _internalReserved;
    unsigned             _internalFlags;

private:
#ifndef __LP64__
    virtual bool initWithOptions(
                               IOOptionBits options,
                               vm_size_t    capacity,
                               vm_offset_t  alignment,
			       task_t	    inTask) APPLE_KEXT_DEPRECATED; /* use withOptions() instead */
#endif /* !__LP64__ */

    virtual bool initWithPhysicalMask(
				task_t		  inTask,
				IOOptionBits      options,
				mach_vm_size_t    capacity,
				mach_vm_address_t alignment,
				mach_vm_address_t physicalMask);

#ifdef __LP64__
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 0);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 1);
#else /* !__LP64__ */
    OSMetaClassDeclareReservedUsed(IOBufferMemoryDescriptor, 0);
    OSMetaClassDeclareReservedUsed(IOBufferMemoryDescriptor, 1);
#endif /* !__LP64__ */
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 2);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 3);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 4);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 5);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 6);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 7);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 8);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 9);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 10);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 11);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 12);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 13);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 14);
    OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 15);

protected:
    virtual void free();

public:

    /*
     * withOptions:
     *
     * Returns a new IOBufferMemoryDescriptor with a buffer large enough to
     * hold capacity bytes.  The descriptor's length is initially set to the
     * capacity.
     */
#ifndef __LP64__
    virtual bool initWithOptions(   IOOptionBits options,
                                    vm_size_t    capacity,
                                    vm_offset_t  alignment) APPLE_KEXT_DEPRECATED; /* use withOptions() instead */
#endif /* !__LP64__ */

    static IOBufferMemoryDescriptor * withOptions(  IOOptionBits options,
                                                    vm_size_t    capacity,
                                                    vm_offset_t  alignment = 1);

/*! @function inTaskWithOptions
    @abstract Creates a memory buffer with memory descriptor for that buffer. 
    @discussion Added in Mac OS X 10.2, this method allocates a memory buffer with a given size and alignment in the task's address space specified, and returns a memory descriptor instance representing the memory. It is recommended that memory allocated for I/O or sharing via mapping be created via IOBufferMemoryDescriptor. Options passed with the request specify the kind of memory to be allocated - pageablity and sharing are specified with option bits. This function may block and so should not be called from interrupt level or while a simple lock is held.
    @param inTask The task the buffer will be allocated in.
    @param options Options for the allocation:<br>
    kIODirectionOut, kIODirectionIn - set the direction of the I/O transfer.<br>
    kIOMemoryPhysicallyContiguous - pass to request memory be physically contiguous. This option is heavily discouraged. The request may fail if memory is fragmented, may cause large amounts of paging activity, and may take a very long time to execute.<br>
    kIOMemoryPageable - pass to request memory be non-wired - the default for kernel allocated memory is wired.<br>
    kIOMemoryPurgeable - pass to request memory that may later have its purgeable state set with IOMemoryDescriptor::setPurgeable. Only supported for kIOMemoryPageable allocations.<br>
    kIOMemoryKernelUserShared - pass to request memory that will be mapped into both the kernel and client applications.
    @param capacity The number of bytes to allocate.
    @param alignment The minimum required alignment of the buffer in bytes - 1 is the default for no required alignment. For example, pass 256 to get memory allocated at an address with bits 0-7 zero.
    @result Returns an instance of class IOBufferMemoryDescriptor to be released by the caller, which will free the memory desriptor and associated buffer. */

    static IOBufferMemoryDescriptor * inTaskWithOptions(
					    task_t       inTask,
                                            IOOptionBits options,
                                            vm_size_t    capacity,
                                            vm_offset_t  alignment = 1);

/*! @function inTaskWithPhysicalMask
    @abstract Creates a memory buffer with memory descriptor for that buffer. 
    @discussion Added in Mac OS X 10.5, this method allocates a memory buffer with a given size and alignment in the task's address space specified, and returns a memory descriptor instance representing the memory. It is recommended that memory allocated for I/O or sharing via mapping be created via IOBufferMemoryDescriptor. Options passed with the request specify the kind of memory to be allocated - pageablity and sharing are specified with option bits. This function may block and so should not be called from interrupt level or while a simple lock is held.
    @param inTask The task the buffer will be mapped in. Pass NULL to create memory unmapped in any task (eg. for use as a DMA buffer).
    @param options Options for the allocation:<br>
    kIODirectionOut, kIODirectionIn - set the direction of the I/O transfer.<br>
    kIOMemoryPhysicallyContiguous - pass to request memory be physically contiguous. This option is heavily discouraged. The request may fail if memory is fragmented, may cause large amounts of paging activity, and may take a very long time to execute.<br>
    kIOMemoryKernelUserShared - pass to request memory that will be mapped into both the kernel and client applications.
    @param capacity The number of bytes to allocate.
    @param mask The buffer will be allocated with pages such that physical addresses will only have bits set present in physicalMask. For example, pass 0x00000000FFFFFFFFULL for a buffer to be accessed by hardware that has 32 address bits.
    @result Returns an instance of class IOBufferMemoryDescriptor to be released by the caller, which will free the memory desriptor and associated buffer. */

    static IOBufferMemoryDescriptor * inTaskWithPhysicalMask(
					    task_t	      inTask,
                                            IOOptionBits      options,
                                            mach_vm_size_t    capacity,
                                            mach_vm_address_t physicalMask);

    /*
     * withCapacity:
     *
     * Returns a new IOBufferMemoryDescriptor with a buffer large enough to
     * hold capacity bytes.  The descriptor's length is initially set to the
     * capacity.
     */
    static IOBufferMemoryDescriptor * withCapacity(
                                     vm_size_t    capacity,
                                     IODirection  withDirection,
                                     bool         withContiguousMemory = false);
#ifndef __LP64__
    virtual bool initWithBytes(const void * bytes,
                               vm_size_t    withLength,
                               IODirection  withDirection,
                               bool         withContiguousMemory = false) APPLE_KEXT_DEPRECATED; /* use withBytes() instead */
#endif /* !__LP64__ */

    /*
     * withBytes:
     *
     * Returns a new IOBufferMemoryDescriptor preloaded with bytes (copied).
     * The descriptor's length and capacity are set to the input buffer's size.
     */
    static IOBufferMemoryDescriptor * withBytes(
                                     const void * bytes,
                                     vm_size_t    withLength,
                                     IODirection  withDirection,
                                     bool         withContiguousMemory = false);

    /*
     * setLength:
     *
     * Change the buffer length of the memory descriptor.  When a new buffer
     * is created, the initial length of the buffer is set to be the same as
     * the capacity.  The length can be adjusted via setLength for a shorter
     * transfer (there is no need to create more buffer descriptors when you
     * can reuse an existing one, even for different transfer sizes).   Note
     * that the specified length must not exceed the capacity of the buffer.
     */
    virtual void setLength(vm_size_t length);

    /*
     * setDirection:
     *
     * Change the direction of the transfer.  This method allows one to redirect
     * the descriptor's transfer direction.  This eliminates the need to destroy
     * and create new buffers when different transfer directions are needed.
     */
    virtual void setDirection(IODirection direction);

    /*
     * getCapacity:
     *
     * Get the buffer capacity
     */
    virtual vm_size_t getCapacity() const;

    /*
     * getBytesNoCopy:
     *
     * Return the virtual address of the beginning of the buffer
     */
    virtual void *getBytesNoCopy();

    /*
     * getBytesNoCopy:
     *
     * Return the virtual address of an offset from the beginning of the buffer
     */
    virtual void *getBytesNoCopy(vm_size_t start, vm_size_t withLength);

    /*
     * appendBytes:
     *
     * Add some data to the end of the buffer.  This method automatically
     * maintains the memory descriptor buffer length.  Note that appendBytes
     * will not copy past the end of the memory descriptor's current capacity.
     */
    virtual bool appendBytes(const void *bytes, vm_size_t withLength);

#ifndef __LP64__
    virtual void * getVirtualSegment(IOByteCount offset,
					IOByteCount * length) APPLE_KEXT_DEPRECATED; /* use getBytesNoCopy() instead */
#endif /* !__LP64__ */
};

#endif /* !_IOBUFFERMEMORYDESCRIPTOR_H */
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
	3	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	#ifndef _IOBUFFERMEMORYDESCRIPTOR_H
	29	#define _IOBUFFERMEMORYDESCRIPTOR_H
	30
	31	#include <IOKit/IOMemoryDescriptor.h>
	32
	33	enum {
1c79356b A	34	kIOMemoryPhysicallyContiguous = 0x00000010,
1c79356b A	35	kIOMemoryPageable = 0x00000020,
91447636	36	kIOMemoryPurgeable = 0x00000040,
1c79356b A	37	kIOMemorySharingTypeMask = 0x000f0000,
1c79356b A	38	kIOMemoryUnshared = 0x00000000,
c910b4d9 A	39	kIOMemoryKernelUserShared = 0x00010000,
	40	// shared IOMemoryDescriptor options for IOBufferMemoryDescriptor:
	41	kIOBufferDescriptorMemoryFlags = kIOMemoryDirectionMask
	42	#ifdef XNU_KERNEL_PRIVATE
	43	\| kIOMemoryAutoPrepare
	44	#endif
	45	\| kIOMemoryThreadSafe
1c79356b A	46	};
1c79356b A	47
9bccf70c	48	#define _IOBUFFERMEMORYDESCRIPTOR_INTASKWITHOPTIONS_ 1
91447636 A	49	/*!
	50	@class IOBufferMemoryDescriptor
	51	@abstract Provides a simple memory descriptor that allocates its own buffer memory.
	52	*/
1c79356b A	53
	54	class IOBufferMemoryDescriptor : public IOGeneralMemoryDescriptor
	55	{
	56	OSDeclareDefaultStructors(IOBufferMemoryDescriptor);
	57
2d21ac55	58	private:
1c79356b A	59	/*! @struct ExpansionData
	60	@discussion This structure will be used to expand the capablilties of this class in the future.
	61	*/
9bccf70c	62	struct ExpansionData {
2d21ac55	63	IOMemoryMap * map;
9bccf70c	64	};
1c79356b A	65
	66	/*! @var reserved
	67	Reserved for future use. (Internal use only) */
	68	ExpansionData * reserved;
	69
	70	protected:
	71	void * _buffer;
	72	vm_size_t _capacity;
	73	vm_offset_t _alignment;
	74	IOOptionBits _options;
b0d623f7 A	75	private:
	76	uintptr_t _internalReserved;
	77	unsigned _internalFlags;
1c79356b A	78
1c79356b A	79	private:
b0d623f7	80	#ifndef __LP64__
9bccf70c A	81	virtual bool initWithOptions(
	82	IOOptionBits options,
	83	vm_size_t capacity,
	84	vm_offset_t alignment,
b0d623f7 A	85	task_t inTask) APPLE_KEXT_DEPRECATED; /* use withOptions() instead */
b0d623f7 A	86	#endif /* !__LP64__ */
0c530ab8	87
0c530ab8 A	88	virtual bool initWithPhysicalMask(
	89	task_t inTask,
	90	IOOptionBits options,
	91	mach_vm_size_t capacity,
	92	mach_vm_address_t alignment,
	93	mach_vm_address_t physicalMask);
2d21ac55	94
b0d623f7 A	95	#ifdef __LP64__
	96	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 0);
	97	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 1);
	98	#else /* !__LP64__ */
2d21ac55	99	OSMetaClassDeclareReservedUsed(IOBufferMemoryDescriptor, 0);
0c530ab8	100	OSMetaClassDeclareReservedUsed(IOBufferMemoryDescriptor, 1);
b0d623f7	101	#endif /* !__LP64__ */
1c79356b A	102	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 2);
	103	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 3);
	104	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 4);
	105	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 5);
	106	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 6);
	107	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 7);
	108	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 8);
	109	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 9);
	110	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 10);
	111	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 11);
	112	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 12);
	113	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 13);
	114	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 14);
	115	OSMetaClassDeclareReservedUnused(IOBufferMemoryDescriptor, 15);
	116
	117	protected:
	118	virtual void free();
	119
1c79356b A	120	public:
	121
	122	/*
	123	* withOptions:
	124	*
	125	* Returns a new IOBufferMemoryDescriptor with a buffer large enough to
	126	* hold capacity bytes. The descriptor's length is initially set to the
	127	* capacity.
	128	*/
b0d623f7	129	#ifndef __LP64__
1c79356b A	130	virtual bool initWithOptions( IOOptionBits options,
1c79356b A	131	vm_size_t capacity,
b0d623f7 A	132	vm_offset_t alignment) APPLE_KEXT_DEPRECATED; /* use withOptions() instead */
b0d623f7 A	133	#endif /* !__LP64__ */
1c79356b A	134
	135	static IOBufferMemoryDescriptor * withOptions( IOOptionBits options,
	136	vm_size_t capacity,
	137	vm_offset_t alignment = 1);
	138
9bccf70c	139	/*! @function inTaskWithOptions
91447636 A	140	@abstract Creates a memory buffer with memory descriptor for that buffer.
91447636 A	141	@discussion Added in Mac OS X 10.2, this method allocates a memory buffer with a given size and alignment in the task's address space specified, and returns a memory descriptor instance representing the memory. It is recommended that memory allocated for I/O or sharing via mapping be created via IOBufferMemoryDescriptor. Options passed with the request specify the kind of memory to be allocated - pageablity and sharing are specified with option bits. This function may block and so should not be called from interrupt level or while a simple lock is held.
9bccf70c	142	@param inTask The task the buffer will be allocated in.
91447636	143	@param options Options for the allocation:<br>
0c530ab8	144	kIODirectionOut, kIODirectionIn - set the direction of the I/O transfer.<br>
91447636 A	145	kIOMemoryPhysicallyContiguous - pass to request memory be physically contiguous. This option is heavily discouraged. The request may fail if memory is fragmented, may cause large amounts of paging activity, and may take a very long time to execute.<br>
	146	kIOMemoryPageable - pass to request memory be non-wired - the default for kernel allocated memory is wired.<br>
	147	kIOMemoryPurgeable - pass to request memory that may later have its purgeable state set with IOMemoryDescriptor::setPurgeable. Only supported for kIOMemoryPageable allocations.<br>
9bccf70c A	148	kIOMemoryKernelUserShared - pass to request memory that will be mapped into both the kernel and client applications.
	149	@param capacity The number of bytes to allocate.
	150	@param alignment The minimum required alignment of the buffer in bytes - 1 is the default for no required alignment. For example, pass 256 to get memory allocated at an address with bits 0-7 zero.
91447636	151	@result Returns an instance of class IOBufferMemoryDescriptor to be released by the caller, which will free the memory desriptor and associated buffer. */
9bccf70c A	152
	153	static IOBufferMemoryDescriptor * inTaskWithOptions(
	154	task_t inTask,
	155	IOOptionBits options,
	156	vm_size_t capacity,
	157	vm_offset_t alignment = 1);
	158
0c530ab8 A	159	/*! @function inTaskWithPhysicalMask
	160	@abstract Creates a memory buffer with memory descriptor for that buffer.
	161	@discussion Added in Mac OS X 10.5, this method allocates a memory buffer with a given size and alignment in the task's address space specified, and returns a memory descriptor instance representing the memory. It is recommended that memory allocated for I/O or sharing via mapping be created via IOBufferMemoryDescriptor. Options passed with the request specify the kind of memory to be allocated - pageablity and sharing are specified with option bits. This function may block and so should not be called from interrupt level or while a simple lock is held.
	162	@param inTask The task the buffer will be mapped in. Pass NULL to create memory unmapped in any task (eg. for use as a DMA buffer).
	163	@param options Options for the allocation:<br>
	164	kIODirectionOut, kIODirectionIn - set the direction of the I/O transfer.<br>
	165	kIOMemoryPhysicallyContiguous - pass to request memory be physically contiguous. This option is heavily discouraged. The request may fail if memory is fragmented, may cause large amounts of paging activity, and may take a very long time to execute.<br>
	166	kIOMemoryKernelUserShared - pass to request memory that will be mapped into both the kernel and client applications.
	167	@param capacity The number of bytes to allocate.
	168	@param mask The buffer will be allocated with pages such that physical addresses will only have bits set present in physicalMask. For example, pass 0x00000000FFFFFFFFULL for a buffer to be accessed by hardware that has 32 address bits.
	169	@result Returns an instance of class IOBufferMemoryDescriptor to be released by the caller, which will free the memory desriptor and associated buffer. */
	170
	171	static IOBufferMemoryDescriptor * inTaskWithPhysicalMask(
	172	task_t inTask,
	173	IOOptionBits options,
	174	mach_vm_size_t capacity,
	175	mach_vm_address_t physicalMask);
0c530ab8	176
1c79356b A	177	/*
	178	* withCapacity:
	179	*
	180	* Returns a new IOBufferMemoryDescriptor with a buffer large enough to
	181	* hold capacity bytes. The descriptor's length is initially set to the
	182	* capacity.
	183	*/
	184	static IOBufferMemoryDescriptor * withCapacity(
	185	vm_size_t capacity,
	186	IODirection withDirection,
	187	bool withContiguousMemory = false);
b0d623f7	188	#ifndef __LP64__
1c79356b A	189	virtual bool initWithBytes(const void * bytes,
	190	vm_size_t withLength,
	191	IODirection withDirection,
b0d623f7 A	192	bool withContiguousMemory = false) APPLE_KEXT_DEPRECATED; /* use withBytes() instead */
b0d623f7 A	193	#endif /* !__LP64__ */
1c79356b A	194
	195	/*
	196	* withBytes:
	197	*
	198	* Returns a new IOBufferMemoryDescriptor preloaded with bytes (copied).
	199	* The descriptor's length and capacity are set to the input buffer's size.
	200	*/
	201	static IOBufferMemoryDescriptor * withBytes(
	202	const void * bytes,
	203	vm_size_t withLength,
	204	IODirection withDirection,
	205	bool withContiguousMemory = false);
	206
	207	/*
	208	* setLength:
	209	*
	210	* Change the buffer length of the memory descriptor. When a new buffer
	211	* is created, the initial length of the buffer is set to be the same as
	212	* the capacity. The length can be adjusted via setLength for a shorter
	213	* transfer (there is no need to create more buffer descriptors when you
	214	* can reuse an existing one, even for different transfer sizes). Note
	215	* that the specified length must not exceed the capacity of the buffer.
	216	*/
	217	virtual void setLength(vm_size_t length);
	218
	219	/*
	220	* setDirection:
	221	*
	222	* Change the direction of the transfer. This method allows one to redirect
	223	* the descriptor's transfer direction. This eliminates the need to destroy
	224	* and create new buffers when different transfer directions are needed.
	225	*/
	226	virtual void setDirection(IODirection direction);
	227
	228	/*
	229	* getCapacity:
	230	*
	231	* Get the buffer capacity
	232	*/
	233	virtual vm_size_t getCapacity() const;
	234
	235	/*
	236	* getBytesNoCopy:
	237	*
	238	* Return the virtual address of the beginning of the buffer
	239	*/
	240	virtual void *getBytesNoCopy();
	241
	242	/*
	243	* getBytesNoCopy:
	244	*
	245	* Return the virtual address of an offset from the beginning of the buffer
	246	*/
	247	virtual void *getBytesNoCopy(vm_size_t start, vm_size_t withLength);
	248
	249	/*
	250	* appendBytes:
	251	*
	252	* Add some data to the end of the buffer. This method automatically
	253	* maintains the memory descriptor buffer length. Note that appendBytes
	254	* will not copy past the end of the memory descriptor's current capacity.
	255	*/
	256	virtual bool appendBytes(const void *bytes, vm_size_t withLength);
0c530ab8	257
b0d623f7 A	258	#ifndef __LP64__
	259	virtual void * getVirtualSegment(IOByteCount offset,
	260	IOByteCount * length) APPLE_KEXT_DEPRECATED; /* use getBytesNoCopy() instead */
	261	#endif /* !__LP64__ */
1c79356b A	262	};
	263
	264	#endif /* !_IOBUFFERMEMORYDESCRIPTOR_H */