1.\" $NetBSD: usb.3,v 1.13 2000/09/24 02:17:52 augustss Exp $ 2.\" 3.\" Copyright (c) 1999, 2001 Lennart Augustsson <augustss@NetBSD.org> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd December 29, 2001 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 usbhid.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" "int id" 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" "hid_kind_t k" "int id" 66.Ft int 67.Fn hid_locate "report_desc_t d" "u_int usage" "hid_kind_t k" "hid_item_t *h" "int id" 68.Ft "char *" 69.Fn hid_usage_page "int i" 70.Ft "char *" 71.Fn hid_usage_in_page "u_int u" 72.Ft int 73.Fn hid_parse_usage_page "const char *" 74.Ft "char *" 75.Fn hid_parse_usage_in_page "const char *" 76.Ft void 77.Fn hid_init "char *file" 78.Ft int 79.Fn hid_get_data "void *data" "hid_item_t *h" 80.Ft void 81.Fn hid_set_data "void *data" "hid_item_t *h" "u_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 way. 88The 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. 103Alternatively a data buffer containing the report descriptor can be 104passed into 105.Fn hid_use_report_desc . 106The data is copied into an internal structure. 107When the report descriptor 108is no longer needed it should be freed by calling 109.Fn hid_dispose_report_desc . 110The type 111.Vt report_desc_t 112is opaque and should be used when calling the parsing functions. 113If 114.Fn hid_dispose_report_desc 115fails it will return 116.Dv NULL . 117.Ss Descriptor Parsing Functions 118To parse the report descriptor the 119.Fn hid_start_parse 120function should be called with a report descriptor and a set that 121describes which items that are interesting. 122The set is obtained by OR-ing together values 123.Fa "(1 << k)" 124where 125.Fa k 126is an item of type 127.Vt hid_kind_t . 128The report ID (if present) is given by 129.Fa id . 130The function returns 131.Dv NULL 132if the initialization fails, otherwise an opaque value to be used 133in subsequent calls. 134After parsing the 135.Fn hid_end_parse 136function should be called to free internal data structures. 137.Pp 138To iterate through all the items in the report descriptor 139.Fn hid_get_item 140should be called while it returns a value greater than 0. 141When the report descriptor ends it will returns 0; a syntax 142error within the report descriptor will cause a return value less 143than 0. 144The struct pointed to by 145.Fa h 146will be filled with the relevant data for the item. 147The definition of 148.Vt hid_item_t 149can be found in 150.In usbhid.h 151and the meaning of the components in the USB HID documentation. 152.Pp 153Data should be read/written to the device in the size of 154the report. 155The size of a report (of a certain kind) can be computed by the 156.Fn hid_report_size 157function. 158If the report is prefixed by an ID byte it is given by 159.Fa id . 160.Pp 161To locate a single item the 162.Fn hid_locate 163function can be used. 164It should be given the usage code of 165the item and its kind and it will fill the item and return 166non-zero if the item was found. 167.Ss Name Translation Functions 168The function 169.Fn hid_usage_page 170will return the symbolic name of a usage page, and the function 171.Fn hid_usage_in_page 172will return the symbolic name of the usage within the page. 173Both these functions may return a pointer to static data. 174.Pp 175The functions 176.Fn hid_parse_usage_page 177and 178.Fn hid_parse_usage_in_page 179are the inverses of 180.Fn hid_usage_page 181and 182.Fn hid_usage_in_page . 183They take a usage string and return the number of the usage, or \-1 184if it cannot be found. 185.Pp 186Before any of these functions can be called the usage table 187must be parsed, this is done by calling 188.Fn hid_init 189with the name of the table. 190Passing 191.Dv NULL 192to this function will cause it to use the default table. 193.Ss Data Extraction Functions 194Given the data obtained from a HID device and an item in the 195report descriptor the 196.Fn hid_get_data 197function extracts the value of the item. 198Conversely 199.Fn hid_set_data 200can be used to put data into a report (which must be zeroed first). 201.Sh EXAMPLES 202Not yet. 203.Sh FILES 204.Bl -tag -width ".Pa /usr/share/misc/usb_hid_usages" 205.It Pa /usr/share/misc/usb_hid_usages 206The default HID usage table. 207.El 208.Sh BUGS 209This man page is woefully incomplete. 210.Sh SEE ALSO 211The 212.Tn USB 213specifications can be found at 214.Pa http://www.usb.org/developers/docs.html . 215.Pp 216.Xr uhid 4 , 217.Xr usb 4 218.Sh HISTORY 219The 220.Nm 221library first appeared in 222.Nx 1.5 . 223