report_desc_t
hid_get_report_desc(int file)
report_desc_t
hid_use_report_desc(const uint8_t *data, unsigned int size)
void
hid_dispose_report_desc(report_desc_t d)
hid_data_t
hid_start_parse(report_desc_t d, int kindset, int id)
void
hid_end_parse(hid_data_t s)
int
hid_get_item(hid_data_t s, hid_item_t *h)
int
hid_report_size(report_desc_t d, hid_kind_t k, int id)
int
hid_locate(report_desc_t d, u_int usage, hid_kind_t k, hid_item_t *h, int id)
char *
hid_usage_page(int i)
char *
hid_usage_in_page(u_int u)
int
hid_parse_usage_page(const char *)
char *
hid_parse_usage_in_page(const char *)
void
hid_init(char *file)
int
hid_get_data(void *data, hid_item_t *h)
void
hid_set_data(void *data, hid_item_t *h, u_int data)
The routines can be divided into four parts: extraction of the descriptor, parsing of the descriptor, translating to/from symbolic names, and data manipulation.
)
with a file descriptor obtained by opening a
uhid(4)
device.
Alternatively a data buffer containing the report descriptor can be
passed into
hid_use_report_desc().
The data is copied into an internal structure.
When the report descriptor
is no longer needed it should be freed by calling
hid_dispose_report_desc().
The type
report_desc_t
is opaque and should be used when calling the parsing functions.
If
hid_dispose_report_desc()
fails it will return
NULL.
)
function should be called with a report descriptor and a set that
describes which items that are interesting.
The set is obtained by or-ing together values
(1 << k)
where
k
is an item of type
hid_kind_t.
The report ID (if present) is given by
id.
The function returns
NULL
if the initialization fails, otherwise an opaque value to be used
in subsequent calls.
After parsing the
hid_end_parse()
function should be called to free internal data structures.
To iterate through all the items in the report descriptor,
hid_get_item()
should be called while it returns a value greater than 0.
When the report descriptor ends it will return 0; a syntax
error within the report descriptor will cause a return value less
than 0.
The struct pointed to by
h
will be filled with the relevant data for the item.
The definition of
hid_item_t
can be found in
<usbhid.h>
and the meaning of the components in the USB HID documentation.
Data should be read/written to the device in the size of
the report.
The size of a report (of a certain kind) can be computed by the
hid_report_size()
function.
If the report is prefixed by an ID byte it is given by
id.
To locate a single item the
hid_locate()
function can be used.
It should be given the usage code of
the item and its kind and it will fill the item and return
non-zero if the item was found.
)
will return the symbolic name of a usage page, and the function
hid_usage_in_page()
will return the symbolic name of the usage within the page.
Both these functions may return a pointer to static data.
The functions
hid_parse_usage_page()
and
hid_parse_usage_in_page()
are the inverses of
hid_usage_page()
and
hid_usage_in_page().
They take a usage string and return the number of the usage, or -1
if it cannot be found.
Before any of these functions can be called the usage table
must be parsed, this is done by calling
hid_init()
with the name of the table.
Passing
NULL
to this function will cause it to use the default table.
)
function extracts the value of the item.
Conversely
hid_set_data()
can be used to put data into a report (which must be zeroed first).
/usr/share/misc/usb_hid_usages
The default HID usage table.
The
USB
specifications can be found at
http://www.usb.org/developers/docs.html.