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);
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_get_stats(struct libusb20_device *pdev,
struct libusb20_device_stats *pstats);
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_get_stats() retrieves the device statistics into the
structure pointed to by the pstats argument. This function returns zero
on success else a LIBUSB20_ERROR value is returned.
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
libusb(3), usb(4), usbconfig(8), usbdump(8)
HISTORY
Some parts of the libusb20 API derives from the libusb project at
sourceforge.
FreeBSD 13.1-RELEASE-p6 December 27, 2019 FreeBSD 13.1-RELEASE-p6
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