1.\" $NetBSD: usb.3,v 1.13 2000/09/24 02:17:52 augustss Exp $ 2.\" 3.\" Copyright (c) 1999 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 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 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 123by OR-ing together values 124.Fa "(1 << k)" 125where 126.Fa k 127is an item of type 128.Vt hid_kind_t . 129The function returns 130.Dv NULL 131if the initialization fails, otherwise an opaque value to be used 132in subsequent calls. 133After parsing the 134.Fn hid_end_parse 135function should be called to free internal data structures. 136.Pp 137To iterate through all the items in the report descriptor 138.Fn hid_get_item 139should be called while it returns a value greater than 0. 140When the report descriptor ends it will returns 0; a syntax 141error within the report descriptor will cause a return value less 142than 0. 143The struct pointed to by 144.Fa h 145will be filled with the relevant data for the item. 146The definition of 147.Vt hid_item_t 148can be found in 149.Aq Pa libusbhid.h 150and the meaning of the components in the USB HID documentation. 151.Pp 152Data should be read/written to the device in the size of 153the report. 154The size of a report (of a certain kind) can be 155computed by the 156.Fn hid_report_size 157function. 158.Pp 159To locate a single item the 160.Fn hid_locate 161function can be used. 162It should be given the usage code of 163the item and its kind and it will fill the item and return 164non-zero if the item was found. 165.Ss Name Translation Functions 166The function 167.Fn hid_usage_page 168will return the symbolic name of a usage page, and the function 169.Fn hid_usage_in_page 170will return the symbolic name of the usage within the page. 171Both these functions may return a pointer to static data. 172.Pp 173The functions 174.Fn hid_parse_usage_page 175and 176.Fn hid_parse_usage_in_page 177are the inverses of 178.Fn hid_usage_page 179and 180.Fn hid_usage_in_page . 181They take a usage string and return the number of the usage, or \-1 182if it cannot be found. 183.Pp 184Before any of these functions can be called the usage table 185must be parsed, this is done by calling 186.Fn hid_init 187with the name of the table. 188Passing 189.Dv NULL 190to this function will cause it to use the default table. 191.Ss Data Extraction Functions 192Given the data obtained from a HID device and an item in the 193report descriptor the 194.Fn hid_get_data 195function extracts the value of the item. 196Conversely 197.Fn hid_set_data 198can be used to put data into a report (which must be zeroed first). 199.Sh EXAMPLES 200Not yet. 201.Sh FILES 202.Bl -tag -width ".Pa /usr/share/misc/usb_hid_usages" 203.It Pa /usr/share/misc/usb_hid_usages 204The default HID usage table. 205.El 206.Sh BUGS 207This man page is woefully incomplete. 208.Sh SEE ALSO 209The 210.Tn USB 211specifications can be found at 212.Pa http://www.usb.org/developers/docs.htm . 213.Pp 214.Xr uhid 4 , 215.Xr usb 4 216.Sh HISTORY 217The 218.Nm 219library first appeared in 220.Nx 1.5 . 221