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LIBUSB20(3)	       FreeBSD Library Functions Manual		   LIBUSB20(3)

NAME
     libusb20 -- USB access library

LIBRARY
     USB access	library	(libusb	-lusb)

SYNOPSIS
     #include <libusb20.h>

     int
     libusb20_tr_close(struct libusb20_transfer	*xfer);

     int
     libusb20_tr_open(struct libusb20_transfer *xfer, uint32_t max_buf_size,
	 uint32_t max_frame_count, uint8_t ep_no);

     struct libusb20_transfer*
     libusb20_tr_get_pointer(struct libusb20_device *pdev, uint16_t tr_index);

     uint16_t
     libusb20_tr_get_time_complete(struct libusb20_transfer *xfer);

     uint32_t
     libusb20_tr_get_actual_frames(struct libusb20_transfer *xfer);

     uint32_t
     libusb20_tr_get_actual_length(struct libusb20_transfer *xfer);

     uint32_t
     libusb20_tr_get_max_frames(struct libusb20_transfer *xfer);

     uint32_t
     libusb20_tr_get_max_packet_length(struct libusb20_transfer	*xfer);

     uint32_t
     libusb20_tr_get_max_total_length(struct libusb20_transfer *xfer);

     uint8_t
     libusb20_tr_get_status(struct libusb20_transfer *xfer);

     uint8_t
     libusb20_tr_pending(struct	libusb20_transfer *xfer);

     void
     libusb20_tr_callback_wrapper(struct libusb20_transfer *xfer);

     void
     libusb20_tr_clear_stall_sync(struct libusb20_transfer *xfer);

     void
     libusb20_tr_drain(struct libusb20_transfer	*xfer);

     void
     libusb20_tr_set_buffer(struct libusb20_transfer *xfer, void *buffer,
	 uint16_t fr_index);

     void
     libusb20_tr_set_callback(struct libusb20_transfer *xfer,
	 libusb20_tr_callback_t	*cb);

     void
     libusb20_tr_set_flags(struct libusb20_transfer *xfer, uint8_t flags);

     uint32_t
     libusb20_tr_get_length(struct libusb20_transfer *xfer,
	 uint16_t fr_index);

     void
     libusb20_tr_set_length(struct libusb20_transfer *xfer, uint32_t length,
	 uint16_t fr_index);

     void
     libusb20_tr_set_priv_sc0(struct libusb20_transfer *xfer, void *sc0);

     void
     libusb20_tr_set_priv_sc1(struct libusb20_transfer *xfer, void *sc1);

     void
     libusb20_tr_set_timeout(struct libusb20_transfer *xfer,
	 uint32_t timeout);

     void
     libusb20_tr_set_total_frames(struct libusb20_transfer *xfer,
	 uint32_t nframes);

     void
     libusb20_tr_setup_bulk(struct libusb20_transfer *xfer, void *pbuf,
	 uint32_t length, uint32_t timeout);

     void
     libusb20_tr_setup_control(struct libusb20_transfer	*xfer, void *psetup,
	 void *pbuf, uint32_t timeout);

     void
     libusb20_tr_setup_intr(struct libusb20_transfer *xfer, void *pbuf,
	 uint32_t length, uint32_t timeout);

     void
     libusb20_tr_setup_isoc(struct libusb20_transfer *xfer, void *pbuf,
	 uint32_t length, uint61_t fr_index);

     uint8_t
     libusb20_tr_bulk_intr_sync(struct libusb20_transfer *xfer,	void *pbuf,
	 uint32_t length, uint32_t *pactlen, uint32_t timeout);

     void
     libusb20_tr_start(struct libusb20_transfer	*xfer);

     void
     libusb20_tr_stop(struct libusb20_transfer *xfer);

     void
     libusb20_tr_submit(struct libusb20_transfer *xfer);

     void *
     libusb20_tr_get_priv_sc0(struct libusb20_transfer *xfer);

     void *
     libusb20_tr_get_priv_sc1(struct libusb20_transfer *xfer);

     const char	*
     libusb20_dev_get_backend_name(struct libusb20_device *);

     int
     libusb20_dev_get_info(struct libusb20_device *pdev,
	 struct	usb_device_info	*pinfo);

     int
     libusb20_dev_get_iface_desc(struct	libusb20_device	*pdev,
	 uint8_t iface_index, char *buf, uint8_t len);

     const char	*
     libusb20_dev_get_desc(struct libusb20_device *pdev);

     int
     libusb20_dev_close(struct libusb20_device *pdev);

     int
     libusb20_dev_detach_kernel_driver(struct libusb20_device *pdev,
	 uint8_t iface_index);

     int
     libusb20_dev_set_config_index(struct libusb20_device *pdev,
	 uint8_t configIndex);

     int
     libusb20_dev_get_debug(struct libusb20_device *pdev);

     int
     libusb20_dev_get_fd(struct	libusb20_device	*pdev);

     int
     libusb20_dev_kernel_driver_active(struct libusb20_device *pdev,
	 uint8_t iface_index);

     int
     libusb20_dev_open(struct libusb20_device *pdev, uint16_t transfer_max);

     int
     libusb20_dev_process(struct libusb20_device *pdev);

     int
     libusb20_dev_request_sync(struct libusb20_device *pdev,
	 struct	LIBUSB20_CONTROL_SETUP_DECODED *setup, void *data,
	 uint16_t *pactlen, uint32_t timeout, uint8_t flags);

     int
     libusb20_dev_req_string_sync(struct libusb20_device *pdev,	uint8_t	index,
	 uint16_t langid, void *ptr, uint16_t len);

     int
     libusb20_dev_req_string_simple_sync(struct	libusb20_device	*pdev,
	 uint8_t index,	void *ptr, uint16_t len);

     int
     libusb20_dev_reset(struct libusb20_device *pdev);

     int
     libusb20_dev_check_connected(struct libusb20_device *pdev);

     int
     libusb20_dev_set_power_mode(struct	libusb20_device	*pdev,
	 uint8_t power_mode);

     uint8_t
     libusb20_dev_get_power_mode(struct	libusb20_device	*pdev);

     uint16_t
     libusb20_dev_get_power_usage(struct libusb20_device *pdev);

     int
     libusb20_dev_set_alt_index(struct libusb20_device *pdev,
	 uint8_t iface_index, uint8_t alt_index);

     struct LIBUSB20_DEVICE_DESC_DECODED *
     libusb20_dev_get_device_desc(struct libusb20_device *pdev);

     struct libusb20_config *
     libusb20_dev_alloc_config(struct libusb20_device *pdev,
	 uint8_t config_index);

     struct libusb20_device *
     libusb20_dev_alloc(void);

     uint8_t
     libusb20_dev_get_address(struct libusb20_device *pdev);

     uint8_t
     libusb20_dev_get_parent_address(struct libusb20_device *pdev);

     uint8_t
     libusb20_dev_get_parent_port(struct libusb20_device *pdev);

     uint8_t
     libusb20_dev_get_bus_number(struct	libusb20_device	*pdev);

     uint8_t
     libusb20_dev_get_mode(struct libusb20_device *pdev);

     uint8_t
     libusb20_dev_get_speed(struct libusb20_device *pdev);

     uint8_t
     libusb20_dev_get_config_index(struct libusb20_device *pdev);

     void
     libusb20_dev_free(struct libusb20_device *pdev);

     void
     libusb20_dev_set_debug(struct libusb20_device *pdev, int debug);

     void
     libusb20_dev_wait_process(struct libusb20_device *pdev, int timeout);

     int
     libusb20_be_get_template(struct libusb20_backend *pbe, int	*ptemp);

     int
     libusb20_be_set_template(struct libusb20_backend *pbe, int	temp);

     int
     libusb20_be_get_dev_quirk(struct libusb20_backend *pber, uint16_t index,
	 struct	libusb20_quirk *pq);

     int
     libusb20_be_get_quirk_name(struct libusb20_backend	*pbe, uint16_t index,
	 struct	libusb20_quirk *pq);

     int
     libusb20_be_add_dev_quirk(struct libusb20_backend *pbe,
	 struct	libusb20_quirk *pq);

     int
     libusb20_be_remove_dev_quirk(struct libusb20_backend *pbe,
	 struct	libusb20_quirk *pq);

     struct libusb20_backend *
     libusb20_be_alloc_default(void);

     struct libusb20_backend *
     libusb20_be_alloc_freebsd(void);

     struct libusb20_backend *
     libusb20_be_alloc_linux(void);

     struct libusb20_device *
     libusb20_be_device_foreach(struct libusb20_backend	*pbe,
	 struct	libusb20_device	*pdev);

     void
     libusb20_be_dequeue_device(struct libusb20_backend	*pbe,
	 struct	libusb20_device	*pdev);

     void
     libusb20_be_enqueue_device(struct libusb20_backend	*pbe,
	 struct	libusb20_device	*pdev);

     void
     libusb20_be_free(struct libusb20_backend *pbe);

     uint8_t
     libusb20_me_get_1(const struct libusb20_me_struct *me, uint16_t off);

     uint16_t
     libusb20_me_get_2(const struct libusb20_me_struct *me, uint16_t off);

     uint16_t
     libusb20_me_encode(void *pdata, uint16_t len, const void *pdecoded);

     uint16_t
     libusb20_me_decode(const void *pdata, uint16_t len, void *pdecoded);

     const uint8_t *
     libusb20_desc_foreach(const struct	libusb20_me_struct *me,
	 const uint8_t *pdesc);

     const char	*
     libusb20_strerror(int code);

     const char	*
     libusb20_error_name(int code);

DESCRIPTION
     The libusb20 library implements functions to be able to easily access and
     control USB through the USB file system interface.	 The libusb20 inter-
     faces are specific	to the FreeBSD usb stack and are not available on
     other operating systems, portable applications should consider using
     libusb(3).

USB TRANSFER OPERATIONS
     libusb20_tr_close() will release all kernel resources associated with an
     USB xfer.	This function returns zero upon	success.  Non-zero return val-
     ues indicate a LIBUSB20_ERROR value.

     libusb20_tr_open()	will allocate kernel buffer resources according	to
     max_buf_size and max_frame_count associated with an USB pxfer and bind
     the transfer to the specified ep_no.  max_buf_size	is the minimum buffer
     size which	the data transport layer has to	support.  If max_buf_size is
     zero, the libusb20	library	will use wMaxPacketSize	to compute the buffer
     size.  This can be	useful for isochronous transfers.  The actual buffer
     size can be greater than max_buf_size and is returned by
     libusb20_tr_get_max_total_length().  If max_frame_count is	OR'ed with
     LIBUSB20_MAX_FRAME_PRE_SCALE the remaining	part of	the argument is	con-
     verted from milliseconds into the actual number of	frames rounded up,
     when this function	returns.  This flag is only valid for ISOCHRONOUS
     transfers and has no effect for other transfer types.  The	actual number
     of	frames setup is	found by calling libusb20_tr_get_max_frames().	This
     function returns zero upon	success.  Non-zero return values indicate a
     LIBUSB20_ERROR value.

     libusb20_tr_get_pointer() will return a pointer to	the allocated USB
     transfer according	to the pdev and	tr_index arguments.  This function
     returns NULL in case of failure.

     libusb20_tr_get_time_complete() will return the completion	time of	an USB
     transfer in millisecond units. This function is most useful for
     isochronous USB transfers when doing echo cancelling.

     libusb20_tr_get_actual_frames() will return the actual number of USB
     frames after an USB transfer completed. A value of	zero means that	no
     data was transferred.

     libusb20_tr_get_actual_length() will return the sum of the	actual length
     for all transferred USB frames for	the given USB transfer.

     libusb20_tr_get_max_frames() will return the maximum number of USB	frames
     that were allocated when an USB transfer was setup	for the	given USB
     transfer.

     libusb20_tr_get_max_packet_length() will return the maximum packet	length
     in	bytes associated with the given	USB transfer.  The packet length can
     be	used round up buffer sizes so that short USB packets are avoided for
     proxy buffers.

     libusb20_tr_get_max_total_length()	will return the	maximum	value for the
     data length sum of	all USB	frames associated with an USB transfer.	 In
     case of control transfers the value returned does not include the length
     of	the SETUP packet, 8 bytes, which is part of frame zero.	 The returned
     value of this function is always aligned to the maximum packet size,
     wMaxPacketSize, of	the endpoint which the USB transfer is bound to.

     libusb20_tr_get_status() will return the status of	an USB transfer.  Sta-
     tus values	are defined by a set of	LIBUSB20_TRANSFER_XXX enums.

     libusb20_tr_pending() will	return non-zero	if the given USB transfer is
     pending for completion.  Else this	function returns zero.

     libusb20_tr_callback_wrapper() This is an internal	function used to wrap
     asynchronous USB callbacks.

     libusb20_tr_clear_stall_sync() This is an internal	function used to syn-
     chronously	clear the stall	on the given USB transfer.  Please see the USB
     specification for more information	on stall clearing.  If the given USB
     transfer is pending when this function is called, the USB transfer	will
     complete with an error after that this function has been called.

     libusb20_tr_drain() will stop the given USB transfer and will not return
     until the USB transfer has	been stopped in	hardware.

     libusb20_tr_set_buffer() is used to set the buffer	pointer	for the	given
     USB transfer and fr_index.	 Typically the frame index is zero.

     libusb20_tr_set_callback()	is used	to set the USB callback	for asynchro-
     nous USB transfers.  The callback type is defined by libusb20_tr_call-
     back_t.

     libusb20_tr_set_flags() is	used to	set various USB	flags for the given
     USB transfer.

     LIBUSB20_TRANSFER_SINGLE_SHORT_NOT_OK
		   Report a short frame	as error.

     LIBUSB20_TRANSFER_MULTI_SHORT_NOT_OK
		   Multiple short frames are not allowed.

     LIBUSB20_TRANSFER_FORCE_SHORT
		   All transmitted frames are short terminated.

     LIBUSB20_TRANSFER_DO_CLEAR_STALL
		   Will	do a clear-stall before	starting the transfer.

     libusb20_tr_get_length() returns the length of the	given USB frame	by
     index.  After an USB transfer is complete the USB frame length will get
     updated to	the actual transferred length.

     libusb20_tr_set_length() sets the length of the given USB frame by	index.

     libusb20_tr_set_priv_sc0()	sets private driver pointer number zero.

     libusb20_tr_set_priv_sc1()	sets private driver pointer number one.

     libusb20_tr_set_timeout() sets the	timeout	for the	given USB transfer.  A
     timeout value of zero means no timeout.  The timeout is given in mil-
     liseconds.

     libusb20_tr_set_total_frames() sets the total number of frames that
     should be executed	when the USB transfer is submitted.  The total number
     of	USB frames must	be less	than the maximum number	of USB frames associ-
     ated with the given USB transfer.

     libusb20_tr_setup_bulk() is a helper function for setting up a single
     frame USB BULK transfer.

     libusb20_tr_setup_control() is a helper function for setting up a single
     or	dual frame USB CONTROL transfer	depending on the control transfer
     length.

     libusb20_tr_setup_intr() is a helper function for setting up a single
     frame USB INTERRUPT transfer.

     libusb20_tr_setup_isoc() is a helper function for setting up a multi
     frame USB ISOCHRONOUS transfer.

     libusb20_tr_bulk_intr_sync() will perform a synchronous BULK or INTERRUPT
     transfer having length given by the length	argument and buffer pointer
     given by the pbuf argument	on the USB transfer given by the xfer argu-
     ment.  If the pactlen argument is non-NULL	the actual transfer length
     will be stored at the given pointer destination.  If the timeout argument
     is	non-zero the transfer will timeout after the given value in millisec-
     onds.  This function does not change the transfer flags, like short
     packet not	ok.  This function returns zero	on success else	a
     LIBUSB20_TRANSFER_XXX value is returned.

     libusb20_tr_start() will get the USB transfer started, if not already
     started.  This function will not get the transfer queued in hardware.
     This function is non-blocking.

     libusb20_tr_stop()	will get the USB transfer stopped, if not already
     stopped.  This function is	non-blocking, which means that the actual stop
     can happen	after the return of this function.

     libusb20_tr_submit() will get the USB transfer queued in hardware.

     libusb20_tr_get_priv_sc0()	returns	private	driver pointer number zero
     associated	with an	USB transfer.

     libusb20_tr_get_priv_sc1()	returns	private	driver pointer number one
     associated	with an	USB transfer.

USB DEVICE OPERATIONS
     libusb20_dev_get_backend_name() returns a zero terminated string describ-
     ing the backend used.

     libusb20_dev_get_info() retrieves the BSD specific	usb_device_info	struc-
     ture into the memory location given by pinfo.  The	USB device given by
     pdev must be opened before	this function will succeed.  This function
     returns zero on success else a LIBUSB20_ERROR value is returned.

     libusb20_dev_get_iface_desc() retrieves the kernel	interface description
     for the given USB iface_index.  The format	of the USB interface descrip-
     tion is: "drivername<unit>: <description>"	The description	string is
     always zero terminated.  A	zero length string is written in case no
     driver is attached	to the given interface.	 The USB device	given by pdev
     must be opened before this	function will succeed.	This function returns
     zero on success else a LIBUSB20_ERROR value is returned.

     libusb20_dev_get_desc() returns a zero terminated string describing the
     given USB device.	The format of the string is: "drivername<unit>:
     <description>"

     libusb20_dev_close() will close the given USB device.  This function
     returns zero on success else a LIBUSB20_ERROR value is returned.

     libusb20_dev_detach_kernel_driver() will try to detach the	kernel driver
     for the USB interface given by iface_index.  This function	returns	zero
     on	success	else a LIBUSB20_ERROR value is returned.

     libusb20_dev_set_config_index() will try to set the configuration index
     on	an USB device.	The first configuration	index is zero.	The un-config-
     ure index is 255.	This function returns zero on success else a
     LIBUSB20_ERROR value is returned.

     libusb20_dev_get_debug() returns the debug	level of an USB	device.

     libusb20_dev_get_fd() returns the file descriptor of the given USB
     device.  A	negative value is returned when	no file	descriptor is present.
     The file descriptor can be	used for polling purposes.

     libusb20_dev_kernel_driver_active() returns zero if a kernel driver is
     active on the given USB interface.	 Else a	LIBUSB20_ERROR value is
     returned.

     libusb20_dev_open() opens an USB device so	that setting up	USB transfers
     becomes possible.	The number of USB transfers can	be zero	which means
     only control transfers are	allowed.  This function	returns	zero on	suc-
     cess else a LIBUSB20_ERROR	value is returned.  A return value of
     LIBUSB20_ERROR_BUSY means that the	device is already opened.

     libusb20_dev_process() is called to sync kernel USB transfers with	user-
     land USB transfers.  This function	returns	zero on	success	else a
     LIBUSB20_ERROR value is returned typically	indicating that	the given USB
     device has	been detached.

     libusb20_dev_request_sync() will perform a	synchronous control request on
     the given USB device.  Before this	call will succeed the USB device must
     be	opened.	 setup is a pointer to a decoded and host endian SETUP packet.
     data is a pointer to a data transfer buffer associated with the control
     transaction. This argument	can be NULL.  pactlen is a pointer to a	vari-
     able that will hold the actual transfer length after the control transac-
     tion is complete.	timeout	is the transaction timeout given in millisec-
     onds.  A timeout of zero means no timeout.	 flags is used to specify
     transaction flags,	for example LIBUSB20_TRANSFER_SINGLE_SHORT_NOT_OK.
     This function returns zero	on success else	a LIBUSB20_ERROR value is
     returned.

     libusb20_dev_req_string_sync() will synchronously request an USB string
     by	language ID and	string index into the given buffer limited by a	maxi-
     mum length.  This function	returns	zero on	success	else a LIBUSB20_ERROR
     value is returned.

     libusb20_dev_req_string_simple_sync() will	synchronously request an USB
     string using the default language ID and convert the string into ASCII
     before storing the	string into the	given buffer limited by	a maximum
     length which includes the terminating zero.  This function	returns	zero
     on	success	else a LIBUSB20_ERROR value is returned.

     libusb20_dev_reset() will try to BUS reset	the given USB device and
     restore the last set USB configuration.  This function returns zero on
     success else a LIBUSB20_ERROR value is returned.

     libusb20_dev_check_connected() will check if an opened USB	device is
     still connected.  This function returns zero if the device	is still con-
     nected else a LIBUSB20_ERROR value	is returned.

     libusb20_dev_set_power_mode() sets	the power mode of the USB device.
     Valid power modes:

     LIBUSB20_POWER_OFF

     LIBUSB20_POWER_ON

     LIBUSB20_POWER_SAVE

     LIBUSB20_POWER_SUSPEND

     LIBUSB20_POWER_RESUME
     This function returns zero	on success else	a LIBUSB20_ERROR value is
     returned.

     libusb20_dev_get_power_mode() returns the currently selected power	mode
     for the given USB device.

     libusb20_dev_get_power_usage() returns the	reported power usage in	mil-
     liamps for	the given USB device.  A power usage of	zero typically means
     that the device is	self powered.

     libusb20_dev_set_alt_index() will try to set the given alternate index
     for the given USB interface index.	 This function returns zero on success
     else a LIBUSB20_ERROR value is returned.

     libusb20_dev_get_device_desc() returns a pointer to the decoded and host
     endian version of the device descriptor.  The USB device need not be
     opened when calling this function.

     libusb20_dev_alloc_config() will read out and decode the USB config
     descriptor	for the	given USB device and config index. This	function
     returns a pointer to the decoded configuration which must eventually be
     passed to free(). NULL is returned	in case	of failure.

     libusb20_dev_alloc() is an	internal function to allocate a	new USB
     device.

     libusb20_dev_get_address()	returns	the internal and not necessarily the
     real hardware address of the given	USB device.  Valid addresses start at
     one.

     libusb20_dev_get_parent_address() returns the internal and	not necessar-
     ily the real hardware address of the given	parent USB HUB device.	This
     value is zero for the root	HUB which usually has a	device address equal
     to	one.  Valid addresses start at one.

     libusb20_dev_get_parent_port() returns the	port number on the parent USB
     HUB device.  This value is	zero for the root HUB which usually has	a
     device address equal to one.  Valid port numbers start at one.

     libusb20_dev_get_bus_number() returns the internal	bus number which the
     given USB device belongs to.  Valid bus numbers start at zero.

     libusb20_dev_get_mode() returns the current operation mode	of the USB
     entity.  Valid return values are:

     LIBUSB20_MODE_HOST

     LIBUSB20_MODE_DEVICE

     libusb20_dev_get_speed() returns the current speed	of the given USB
     device.

     LIBUSB20_SPEED_UNKNOWN

     LIBUSB20_SPEED_LOW

     LIBUSB20_SPEED_FULL

     LIBUSB20_SPEED_HIGH

     LIBUSB20_SPEED_VARIABLE

     LIBUSB20_SPEED_SUPER

     libusb20_dev_get_config_index() returns the currently selected config
     index for the given USB device.

     libusb20_dev_free() will free the given USB device	and all	associated USB
     transfers.

     libusb20_dev_set_debug() will set the debug level for the given USB
     device.

     libusb20_dev_wait_process() will wait until a pending USB transfer	has
     completed on the given USB	device.	 A timeout value can be	specified
     which is passed on	to the poll(2) function.

USB BACKEND OPERATIONS
     libusb20_be_get_template()	will return the	currently selected global USB
     device side mode template into the	integer	pointer	ptemp.	This function
     returns zero on success else a LIBUSB20_ERROR value is returned.

     libusb20_be_set_template()	will set the global USB	device side mode tem-
     plate to temp.  The new template is not activated until after the next
     USB enumeration.  The template number decides how the USB device will
     present itself to the USB Host, like Mass Storage Device, USB Ethernet
     Device. Also see the usb2_template(4) module.  This function returns zero
     on	success	else a LIBUSB20_ERROR value is returned.

     libusb20_be_get_dev_quirk() will return the device	quirk according	to
     index into	the libusb20_quirk structure pointed to	by pq.	This function
     returns zero on success else a LIBUSB20_ERROR value is returned.  If the
     given quirk does not exist	LIBUSB20_ERROR_NOT_FOUND is returned.

     libusb20_be_get_quirk_name() will return the quirk	name according to
     index into	the libusb20_quirk structure pointed to	by pq.	This function
     returns zero on success else a LIBUSB20_ERROR value is returned.  If the
     given quirk does not exist	LIBUSB20_ERROR_NOT_FOUND is returned.

     libusb20_be_add_dev_quirk() will add the libusb20_quirk structure pointed
     to	by the pq argument into	the device quirk list.	This function returns
     zero on success else a LIBUSB20_ERROR value is returned.  If the given
     quirk cannot be added LIBUSB20_ERROR_NO_MEM is returned.

     libusb20_be_remove_dev_quirk() will remove	the quirk matching the
     libusb20_quirk structure pointed to by the	pq argument from the device
     quirk list.  This function	returns	zero on	success	else a LIBUSB20_ERROR
     value is returned.	 If the	given quirk does not exist
     LIBUSB20_ERROR_NOT_FOUND is returned.

     libusb20_be_alloc_default() libusb20_be_alloc_freebsd()
     libusb20_be_alloc_linux() These functions are used	to allocate a specific
     USB backend or the	operating system default USB backend. Allocating a
     backend is	a way to scan for currently present USB	devices.

     libusb20_be_device_foreach() is used to iterate USB devices present in a
     USB backend.  The starting	value of pdev is NULL.	This function returns
     the next USB device in the	list.  If NULL is returned the end of the USB
     device list has been reached.

     libusb20_be_dequeue_device() will dequeue the given USB device pointer
     from the backend USB device list.	Dequeued USB devices will not be freed
     when the backend is freed.

     libusb20_be_enqueue_device() will enqueue the given USB device pointer in
     the backend USB device list.  Enqueued USB	devices	will get freed when
     the backend is freed.

     libusb20_be_free()	will free the given backend and	all USB	devices	in its
     device list.

USB DESCRIPTOR PARSING
     libusb20_me_get_1(pie, offset) This function will return a	byte at	the
     given byte	offset of a message entity.  This function is safe against
     invalid offsets.

     libusb20_me_get_2(pie, offset) This function will return a	little endian
     16-bit value at the given byte offset of a	message	entity.	 This function
     is	safe against invalid offsets.

     libusb20_me_encode(pbuf, len, pdecoded) This function will	encode a so-
     called *DECODED structure into binary format.  The	total encoded length
     that will fit in the given	buffer is returned.  If	the buffer pointer is
     NULL no data will be written to the buffer	location.

     libusb20_me_decode(pbuf, len, pdecoded) This function will	decode a
     binary structure into a so-called *DECODED	structure.  The	total decoded
     length is returned.  The buffer pointer cannot be NULL.

USB DEBUGGING
     const char	* libusb20_strerror(int	code) Get the ASCII representation of
     the error given by	the code argument.  This function does not return
     NULL.

     const char	* libusb20_error_name(int code)	Get the	ASCII representation
     of	the error enum given by	the code argument.  This function does not
     return NULL.

FILES
     /dev/usb

SEE ALSO
     usb(4), libusb(3),	usbconfig(8), usbdump(8)

HISTORY
     Some parts	of the libusb20	API derives from the libusb project at source-
     forge.

FreeBSD	9.3		       February	14, 2013		   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | USB TRANSFER OPERATIONS | USB DEVICE OPERATIONS | USB BACKEND OPERATIONS | USB DESCRIPTOR PARSING | USB DEBUGGING | FILES | SEE ALSO | HISTORY

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