usb.core
Class Descriptor

java.lang.Object
  |
  +--usb.core.Descriptor

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

Configuration, DeviceDescriptor, Endpoint, Hub, Interface

public abstract class Descriptor

extends java.lang.Object

implements java.io.Serializable

This is a base class for entities with USB typed descriptors. It encapsulates raw descriptor data (byte arrays) and provides parsed access to that data. It is intended to be subclassed; subclasses will know how to parse the data after the first two bytes that this base class parses.

Descriptors are discussed in sections 9.5 and 9.6 of the USB 1.1 specification.

See Also:

Serialized Form

Field Summary

static byte	CLASS_APP_SPECIFIC Identifier for application-specific interfaces.
static byte	CLASS_AUDIO Identifier for audio class interfaces.
static byte	CLASS_COMM Identifier for communications control class interfaces.
static byte	CLASS_DATA Identifier for communications data class interfaces.
static byte	CLASS_HID Identifier for Human Interaction Device (HID) class interfaces.
static byte	CLASS_HUB Identifier for hub class interfaces.
static byte	CLASS_MASS_STORAGE Identifier for mass storage class interfaces.
static byte	CLASS_PRINTER Identifier for printer class interfaces.
static byte	CLASS_VENDOR_SPECIFIC Identifier for vendor-specific interfaces.
static byte	TYPE_CONFIGURATION Indicates a configuration descriptor
static byte	TYPE_DEVICE Indicates a device descriptor
static byte	TYPE_DEVICE_QUALIFIER Indicates a USB 2.0 "device qualifier"
static byte	TYPE_ENDPOINT Indicates an endpoint descriptor
static byte	TYPE_HID Indicates a hid class descriptor
static byte	TYPE_HUB Indicates a hub class descriptor
static byte	TYPE_INTERFACE Indicates an interface descriptor
static byte	TYPE_INTERFACE_POWER Indicates interface power consumption
static byte	TYPE_OTHER_SPEED Indicates a USB 2.0 "other speed configuration"
static byte	TYPE_PHYSICAL
static byte	TYPE_REPORT
static byte	TYPE_STRING Indicates a string descriptor

Constructor Summary

protected	Descriptor() Used when deserializing.
protected	Descriptor(byte[] raw) Creates and initializes a descriptor

Method Summary

java.lang.String	getBCD(int offset) Returns the two byte BCD string at the specified offset.
static java.lang.String	getClassName(int klass, java.lang.String zeroValue) Returns the name corresponding to an interface class code.
int	getDescriptorType() Returns the descriptor type.
java.lang.String	getDescriptorTypeName() Returns a name for the type of descriptor (such as "device")
abstract Device	getDevice() Returns the device with which this USB object is associated.
int	getLength() Returns the length of the descriptor.
int	getU16(int index) Returns a sixteen bit unsigned integer value, as encoded in the descriptor at the specified byte offset.
int	getU32(int index) Returns a thirty-two bit integer value, as encoded in the descriptor at the specified byte offset.
int	getU8(int index) Returns an eight bit unsigned integer value, as encoded in the descriptor at the specified byte offset.
Descriptor	nextDescriptor() Provides successive access to all the descriptors in a block such a complete configuration descriptor.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TYPE_DEVICE

public static final byte TYPE_DEVICE

Indicates a device descriptor

TYPE_CONFIGURATION

public static final byte TYPE_CONFIGURATION

Indicates a configuration descriptor

TYPE_STRING

public static final byte TYPE_STRING

Indicates a string descriptor

TYPE_INTERFACE

public static final byte TYPE_INTERFACE

Indicates an interface descriptor

TYPE_ENDPOINT

public static final byte TYPE_ENDPOINT

Indicates an endpoint descriptor

TYPE_DEVICE_QUALIFIER

public static final byte TYPE_DEVICE_QUALIFIER

Indicates a USB 2.0 "device qualifier"

TYPE_OTHER_SPEED

public static final byte TYPE_OTHER_SPEED

Indicates a USB 2.0 "other speed configuration"

TYPE_INTERFACE_POWER

public static final byte TYPE_INTERFACE_POWER

Indicates interface power consumption

TYPE_HID

public static final byte TYPE_HID

Indicates a hid class descriptor

TYPE_REPORT

public static final byte TYPE_REPORT

TYPE_PHYSICAL

public static final byte TYPE_PHYSICAL

TYPE_HUB

public static final byte TYPE_HUB

Indicates a hub class descriptor

CLASS_AUDIO

public static final byte CLASS_AUDIO

Identifier for audio class interfaces.

CLASS_COMM

public static final byte CLASS_COMM

Identifier for communications control class interfaces.

CLASS_HID

public static final byte CLASS_HID

Identifier for Human Interaction Device (HID) class interfaces.

CLASS_PRINTER

public static final byte CLASS_PRINTER

Identifier for printer class interfaces.

CLASS_MASS_STORAGE

public static final byte CLASS_MASS_STORAGE

Identifier for mass storage class interfaces.

CLASS_HUB

public static final byte CLASS_HUB

Identifier for hub class interfaces.

CLASS_DATA

public static final byte CLASS_DATA

Identifier for communications data class interfaces.

CLASS_APP_SPECIFIC

public static final byte CLASS_APP_SPECIFIC

Identifier for application-specific interfaces. Subclass codes are used to indicate facilities such as firmware update or an IrDA/USB bridge.

CLASS_VENDOR_SPECIFIC

public static final byte CLASS_VENDOR_SPECIFIC

Identifier for vendor-specific interfaces.

Constructor Detail

Descriptor

protected Descriptor()

Used when deserializing.

Descriptor

protected Descriptor(byte[] raw)

Creates and initializes a descriptor

Method Detail

getDevice

public abstract Device getDevice()

Returns the device with which this USB object is associated.

getLength

public final int getLength()

Returns the length of the descriptor.

getDescriptorType

public final int getDescriptorType()

Returns the descriptor type.

getDescriptorTypeName

public java.lang.String getDescriptorTypeName()

Returns a name for the type of descriptor (such as "device")

getClassName

public static java.lang.String getClassName(int klass,
                                            java.lang.String zeroValue)

Returns the name corresponding to an interface class code. Device class codes are not quite identical to these.

getU8

public final int getU8(int index)

Returns an eight bit unsigned integer value, as encoded in the descriptor at the specified byte offset.

getU16

public final int getU16(int index)

Returns a sixteen bit unsigned integer value, as encoded in the descriptor at the specified byte offset.

getU32

public final int getU32(int index)

Returns a thirty-two bit integer value, as encoded in the descriptor at the specified byte offset. Be careful with sign interpretation.

getBCD

public java.lang.String getBCD(int offset)

Returns the two byte BCD string at the specified offset.

nextDescriptor

public final Descriptor nextDescriptor()

Provides successive access to all the descriptors in a block such a complete configuration descriptor. This returns a "generic" descriptor. Use methods on configurations and interfaces to get Interface and Endpoint descriptor objects. Then if you use this method and see that the type of the resulting descriptor is neither TYPE_INTERFACE nor TYPE_ENDPOINT, you will know that you have some other kind of descriptor, such as a device-specific one.

Returns:

null when no more descriptors are available