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1.\" $NetBSD: usb.3,v 1.13 2000/09/24 02:17:52 augustss Exp $
2.\" $FreeBSD: src/lib/libusbhid/usbhid.3,v 1.11.2.1 2002/04/03 15:54:00 joe Exp $
44cb301e 3.\" $DragonFly: src/lib/libusbhid/usbhid.3,v 1.5 2006/05/26 19:39:38 swildner Exp $
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4.\"
5.\" Copyright (c) 1999 Lennart Augustsson <augustss@netbsd.org>
6.\" All rights reserved.
7.\"
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9.\" modification, are permitted provided that the following conditions
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28.\"
29.Dd May 11, 1999
30.Dt USBHID 3
31.Os
32.Sh NAME
33.Nm usbhid ,
34.Nm hid_get_report_desc ,
35.Nm hid_use_report_desc ,
36.Nm hid_dispose_report_desc ,
37.Nm hid_start_parse ,
38.Nm hid_end_parse ,
39.Nm hid_get_item ,
40.Nm hid_report_size ,
41.Nm hid_locate ,
42.Nm hid_usage_page ,
43.Nm hid_usage_in_page ,
44.Nm hid_init ,
45.Nm hid_get_data ,
46.Nm hid_set_data
47.Nd USB HID access routines
48.Sh LIBRARY
49.Lb libusbhid
50.Sh SYNOPSIS
51.In libusbhid.h
52.Ft report_desc_t
53.Fn hid_get_report_desc "int file"
54.Ft report_desc_t
55.Fn hid_use_report_desc "unsigned char *data" "unsigned int size"
56.Ft void
57.Fn hid_dispose_report_desc "report_desc_t d"
58.Ft hid_data_t
59.Fn hid_start_parse "report_desc_t d" "int kindset"
60.Ft void
61.Fn hid_end_parse "hid_data_t s"
62.Ft int
63.Fn hid_get_item "hid_data_t s" "hid_item_t *h"
64.Ft int
65.Fn hid_report_size "report_desc_t d" "unsigned int id" "hid_kind_t k"
66.Ft int
67.Fn hid_locate "report_desc_t d" "unsigned int usage" "hid_kind_t k" "hid_item_t *h"
68.Ft const char *
69.Fn hid_usage_page "int i"
70.Ft const char *
71.Fn hid_usage_in_page "unsigned int u"
72.Ft int
73.Fn hid_parse_usage_page "const char *name"
74.Ft int
75.Fn hid_parse_usage_in_page "const char *name"
76.Ft void
77.Fn hid_init "const char *file"
78.Ft int
79.Fn hid_get_data "const void *data" "const hid_item_t *h"
80.Ft void
81.Fn hid_set_data "void *p" "const hid_item_t *h" "int data"
82.Sh DESCRIPTION
83The
84.Nm
85library provides routines to extract data from USB Human Interface Devices.
86.Ss INTRODUCTION
87USB HID devices send and receive data layed out in a device dependent
88way. The
89.Nm
90library contains routines to extract the
91.Em report descriptor
92which contains the data layout information and then use this information.
93.Pp
94The routines can be divided into four parts: extraction of the descriptor,
95parsing of the descriptor, translating to/from symbolic names, and
96data manipulation.
97.Ss DESCRIPTOR FUNCTIONS
98A report descriptor can be obtained by calling
99.Fn hid_get_report_desc
100with a file descriptor obtained by opening a
101.Xr uhid 4
102device. Alternatively a data buffer containing the report descriptor can be
103passed into
104.Fn hid_use_report_desc .
105The data is copied into an internal structure. When the report descriptor
106is no longer needed it should be freed by calling
107.Fn hid_dispose_report_desc .
108The type
109.Fa report_desc_t
110is opaque and should be used when calling the parsing functions.
111If
112.Fn hid_dispose_report_desc
113fails it will return
114.Fa NULL .
115.Ss DESCRIPTOR PARSING FUNCTIONS
116To parse the report descriptor the
117.Fn hid_start_parse
118function should be called with a report descriptor and a set that
119describes which items that are interesting. The set is obtained
120by or-ing together values
121.Fa "(1 << k)"
122where
123.Fa k
124is an item of type
125.Fa hid_kind_t .
126The function returns
127.Fa NULL
128if the initialization fails, otherwise an opaque value to be used
129in subsequent calls.
130After parsing the
131.Fn hid_end_parse
132function should be called to free internal data structures.
133.Pp
134To iterate through all the items in the report descriptor
135.Fn hid_get_item
136should be called while it returns a value greater than 0.
137When the report descriptor ends it will returns 0; a syntax
138error within the report descriptor will cause a return value less
139than 0.
140The struct pointed to by
141.Fa h
142will be filled with the relevant data for the item.
143The definition of
144.Fa hid_item_t
145can be found in
44cb301e 146.In libusbhid.h
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147and the meaning of the components in the USB HID documentation.
148.Pp
149Data should be read/written to the device in the size of
150the report. The size of a report (of a certain kind) can be
151computed by the
152.Fn hid_report_size
153function.
154.Pp
155To locate a single item the
156.Fn hid_locate
157function can be used. It should be given the usage code of
158the item and its kind and it will fill the item and return
159non-zero if the item was found.
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160.Ss NAME TRANSLATION FUNCTIONS
161The function
162.Fn hid_usage_page
163will return the symbolic name of a usage page, and the function
164.Fn hid_usage_in_page
165will return the symbolic name of the usage within the page.
166Both these functions may return a pointer to static data.
167.Pp
168The functions
169.Fn hid_parse_usage_page
170and
171.Fn hid_parse_usage_in_page
172are the inverses of
173.Fn hid_usage_page
174and
175.Fn hid_usage_in_page .
176They take a usage string and return the number of the usage, or -1
177if it cannot be found.
178.Pp
179Before any of these functions can be called the usage table
180must be parsed, this is done by calling
181.Fn hid_init
182with the name of the table. Passing
183.Fa NULL
184to this function will cause it to use the default table.
185.Ss DATA EXTRACTION FUNCTIONS
186Given the data obtained from a HID device and an item in the
187report descriptor the
188.Fn hid_get_data
189function extracts the value of the item.
190Conversely
191.Fn hid_set_data
192can be used to put data into a report (which must be zeroed first).
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193.Sh FILES
194.Pa /usr/share/misc/usb_hid_usages
195The default HID usage table.
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196.Sh EXAMPLES
197Not yet.
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198.Sh SEE ALSO
199The
200.Tn USB
201specifications can be found at
202.Dv http://www.usb.org/developers/docs.htm .
203.Pp
204.Xr uhid 4 ,
205.Xr usb 4
206.Sh HISTORY
207The
208.Nm
209library first appeared in
210.Nx 1.5 .
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211.Sh BUGS
212This man page is woefully incomplete.