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);
libusb20_tr_open_stream
(struct
libusb20_transfer *xfer,
uint32_t max_buf_size,
uint32_t max_frame_count,
uint8_t ep_no,
uint16_t stream_id);
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_port_path
(struct
libusb20_device *pdev,
uint8_t *buf,
uint8_t bufsize);
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
interfaces 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 values 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 converted
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_open_stream
()
is identical to libusb20_tr_open
() except that a
stream ID can be specified for BULK endpoints having such a feature.
libusb20_tr_open
() can be used to open stream ID
zero.
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. Status 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 synchronously 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 asynchronous USB transfers. The callback
type is defined by libusb20_tr_callback_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 milliseconds.
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 associated 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 argument. 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 milliseconds.
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 describing the backend used.
libusb20_dev_get_port_path
()
retrieves the list of USB port numbers which the datastream for a given USB
device follows. The first port number is the Root HUB port number. Then
children port numbers follow. The Root HUB device itself has a port path
length of zero. Valid port numbers start at one and range until and
including 255. Typically there should not be more than 16 levels, due to
electrical and protocol limitations. This functions returns the number of
actual port levels upon success else a LIBUSB20_ERROR value is returned
which are always negative. If the actual number of port levels is greater
than the maximum specified, a LIBUSB20_ERROR value is returned.
libusb20_dev_get_info
()
retrieves the BSD specific usb_device_info structure 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
description 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-configure 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 success 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 userland 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 variable that will hold the
actual transfer length after the control transaction is complete.
timeout is the transaction timeout given in
milliseconds. 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 maximum 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 connected 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 milliamps 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 necessarily 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 template 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
HISTORY
Some parts of the libusb20
API derives
from the libusb project at sourceforge.