225 lines
6.5 KiB
Groff
225 lines
6.5 KiB
Groff
.\" $NetBSD: usbhid.3,v 1.13 2010/05/12 18:37:56 plunky Exp $
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.\"
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.\" Copyright (c) 1999, 2001 Lennart Augustsson <augustss@NetBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd May 12, 2010
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.Dt USBHID 3
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.Os
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.Sh NAME
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.Nm usbhid ,
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.Nm hid_get_report_desc ,
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.Nm hid_use_report_desc ,
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.Nm hid_dispose_report_desc ,
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.Nm hid_start_parse ,
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.Nm hid_end_parse ,
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.Nm hid_get_item ,
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.Nm hid_report_size ,
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.Nm hid_locate ,
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.Nm hid_usage_page ,
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.Nm hid_usage_in_page ,
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.Nm hid_init ,
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.Nm hid_get_data ,
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.Nm hid_set_data
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.Nd USB HID access routines
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.Sh LIBRARY
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.Lb libusbhid
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.Sh SYNOPSIS
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.In usbhid.h
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.Ft report_desc_t
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.Fn hid_get_report_desc "int file"
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.Ft report_desc_t
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.Fn hid_use_report_desc "const uint8_t *data" "unsigned int size"
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.Ft void
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.Fn hid_dispose_report_desc "report_desc_t d"
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.Ft hid_data_t
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.Fn hid_start_parse "report_desc_t d" "int kindset" "int id"
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.Ft void
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.Fn hid_end_parse "hid_data_t s"
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.Ft int
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.Fn hid_get_item "hid_data_t s" "hid_item_t *h"
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.Ft int
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.Fn hid_report_size "report_desc_t d" "hid_kind_t k" "int id"
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.Ft int
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.Fn hid_locate "report_desc_t d" "u_int usage" "hid_kind_t k" "hid_item_t *h" "int id"
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.Ft char *
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.Fn hid_usage_page "int i"
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.Ft char *
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.Fn hid_usage_in_page "u_int u"
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.Ft int
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.Fn hid_parse_usage_page "const char *"
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.Ft char *
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.Fn hid_parse_usage_in_page "const char *"
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.Ft void
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.Fn hid_init "const char *file"
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.Ft int
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.Fn hid_get_data "const void *data" "const hid_item_t *h"
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.Ft void
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.Fn hid_set_data "void *data" "const hid_item_t *h" "u_int data"
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.Sh DESCRIPTION
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The
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.Nm
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library provides routines to extract data from USB Human Interface Devices.
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.Ss INTRODUCTION
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USB HID devices send and receive data laid out in a device dependent way.
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The
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.Nm
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library contains routines to extract the
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.Em report descriptor
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which contains the data layout information and then use this information.
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.Pp
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The routines can be divided into four parts: extraction of the descriptor,
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parsing of the descriptor, translating to/from symbolic names, and
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data manipulation.
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.Ss DESCRIPTOR FUNCTIONS
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A report descriptor can be obtained by calling
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.Fn hid_get_report_desc
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with a file descriptor obtained by opening a
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.Xr uhid 4
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device.
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Alternatively a data buffer containing the report descriptor can be
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passed into
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.Fn hid_use_report_desc .
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The data is copied into an internal structure.
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When the report descriptor
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is no longer needed it should be freed by calling
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.Fn hid_dispose_report_desc .
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The type
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.Fa report_desc_t
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is opaque and should be used when calling the parsing functions.
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If
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.Fn hid_dispose_report_desc
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fails it will return
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.Fa NULL .
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.Ss DESCRIPTOR PARSING FUNCTIONS
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To parse the report descriptor the
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.Fn hid_start_parse
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function should be called with a report descriptor and a set that
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describes which items that are interesting.
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The set is obtained by or-ing together values
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.Fa "(1 \*[Lt]\*[Lt] k)"
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where
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.Fa k
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is an item of type
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.Fa hid_kind_t .
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The report ID (if present) is given by
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.Fa id .
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The function returns
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.Fa NULL
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if the initialization fails, otherwise an opaque value to be used
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in subsequent calls.
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After parsing the
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.Fn hid_end_parse
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function should be called to free internal data structures.
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.Pp
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To iterate through all the items in the report descriptor,
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.Fn hid_get_item
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should be called while it returns a value greater than 0.
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When the report descriptor ends it will return 0; a syntax
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error within the report descriptor will cause a return value less
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than 0.
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The struct pointed to by
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.Fa h
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will be filled with the relevant data for the item.
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The definition of
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.Fa hid_item_t
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can be found in
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.In usbhid.h
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and the meaning of the components in the USB HID documentation.
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.Pp
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Data should be read/written to the device in the size of
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the report.
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The size of a report (of a certain kind) can be computed by the
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.Fn hid_report_size
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function.
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If the report is prefixed by an ID byte it is given by
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.Fa id .
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.Pp
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To locate a single item the
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.Fn hid_locate
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function can be used.
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It should be given the usage code of
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the item and its kind and it will fill the item and return
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non-zero if the item was found.
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.Ss NAME TRANSLATION FUNCTIONS
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The function
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.Fn hid_usage_page
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will return the symbolic name of a usage page, and the function
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.Fn hid_usage_in_page
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will return the symbolic name of the usage within the page.
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Both these functions may return a pointer to static data.
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.Pp
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The functions
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.Fn hid_parse_usage_page
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and
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.Fn hid_parse_usage_in_page
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are the inverses of
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.Fn hid_usage_page
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and
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.Fn hid_usage_in_page .
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They take a usage string and return the number of the usage, or -1
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if it cannot be found.
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.Pp
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Before any of these functions can be called the usage table
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must be parsed, this is done by calling
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.Fn hid_init
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with the name of the table.
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Passing
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.Fa NULL
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to this function will cause it to use the default table.
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.Ss DATA EXTRACTION FUNCTIONS
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Given the data obtained from a HID device and an item in the
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report descriptor the
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.Fn hid_get_data
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function extracts the value of the item.
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Conversely
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.Fn hid_set_data
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can be used to put data into a report (which must be zeroed first).
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.Sh FILES
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.Pa /usr/share/misc/usb_hid_usages
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The default HID usage table.
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.\" .Sh EXAMPLES
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.Sh SEE ALSO
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.Xr uhid 4 ,
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.Xr usb 4
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.Pp
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The
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.Tn USB
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specifications can be found at
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.Dv http://www.usb.org/developers/docs.html .
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.Sh HISTORY
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The
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.Nm
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library first appeared in
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.Nx 1.5
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as
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.Nm usb
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library
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and was renamed to
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.Nm
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for
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.Nx 1.6 .
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.Sh BUGS
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This man page is woefully incomplete.
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