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USBHID(3)              FreeBSD Library Functions Manual              USBHID(3)

NAME
     usbhid, hid_get_report_desc, hid_get_report_id, hid_use_report_desc,
     hid_dispose_report_desc, hid_start_parse, hid_end_parse, hid_get_item,
     hid_report_size, hid_locate, hid_usage_page, hid_usage_in_page, hid_init,
     hid_get_data, hid_set_data, hid_get_report, hid_set_report - USB HID
     access routines

LIBRARY
     USB Human Interface Devices Library (libusbhid, -lusbhid)

SYNOPSIS
     #include <usbhid.h>

     report_desc_t
     hid_get_report_desc(int file);

     int
     hid_get_report_id(int file);

     int
     hid_set_immed(int fd, int enable);

     report_desc_t
     hid_use_report_desc(unsigned char *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);

     const char *
     hid_usage_page(int i);

     const char *
     hid_usage_in_page(u_int u);

     int
     hid_parse_usage_page(const char *);

     int
     hid_parse_usage_in_page(const char *);

     void
     hid_init(const char *file);

     int
     hid_get_data(const void *data, const hid_item_t *h);

     void
     hid_set_data(void *buf, const hid_item_t *h, int data);

     int
     hid_get_report(int fd, enum hid_kind k, unsigned char *data,
         unsigned int size);

     int
     hid_set_report(int fd, enum hid_kind k, unsigned char *data,
         unsigned int size);

DESCRIPTION
     The usbhid library provides routines to extract data from USB Human
     Interface Devices.

   Introduction
     USB HID devices send and receive data layed out in a device dependent
     way.  The usbhid library contains routines to extract the report
     descriptor which contains the data layout information and then use this
     information.

     The routines can be divided into four parts: extraction of the
     descriptor, parsing of the descriptor, translating to/from symbolic
     names, and data manipulation.

   Synchronous HID operation
     Synchronous HID operation can be enabled or disabled by a call to
     hid_set_immed().  If the second argument is zero synchronous HID
     operation is disabled.  Else synchronous HID operation is enabled.  The
     function returns a negative value on failure.

     hid_get_report() and hid_set_report() functions allow to synchronously
     get and set specific report if device supports it.  For devices with
     multiple report IDs, wanted ID should be provided in the first byte of
     the buffer for both get and set.

   Descriptor Functions
     The report descriptor ID can be obtained by calling hid_get_report_id().
     A report descriptor can be obtained by calling hid_get_report_desc() 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.

   Descriptor Parsing Functions
     To parse the report descriptor the hid_start_parse() function should be
     called with a report descriptor, a set that describes which items that
     are interesting, and the desired report ID (or -1 to obtain items of all
     report IDs).  The set is obtained by OR-ing together values (1 __ k)
     where k is an item of type hid_kind_t.  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 returns 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.

   Name Translation Functions
     The function hid_usage_page() 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.

   Data Extraction Functions
     Given the data obtained from a HID device and an item in the report
     descriptor the hid_get_data() 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).

FILES
     /usr/share/misc/usb_hid_usages      The default HID usage table.

EXAMPLES
     Not yet.

SEE ALSO
     The USB specifications can be found at
     http://www.usb.org/developers/docs/.

     uhid(4), usb(4)

HISTORY
     The usbhid library first appeared in NetBSD 1.5.

BUGS
     This man page is woefully incomplete.

FreeBSD 11.0-PRERELEASE        January 27, 2009        FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | HISTORY | BUGS

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