1.\" $NetBSD: usb.3,v 1.13 2000/09/24 02:17:52 augustss Exp $ 2.\" $FreeBSD$ 3.\" 4.\" Copyright (c) 1999 Lennart Augustsson <augustss@netbsd.org> 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd May 11, 1999 29.Dt USB 3 30.Os 31.Sh NAME 32.Nm usb , 33.Nm hid_get_report_desc , 34.Nm hid_use_report_desc , 35.Nm hid_dispose_report_desc , 36.Nm hid_start_parse , 37.Nm hid_end_parse , 38.Nm hid_get_item , 39.Nm hid_report_size , 40.Nm hid_locate , 41.Nm hid_usage_page , 42.Nm hid_usage_in_page , 43.Nm hid_init , 44.Nm hid_get_data , 45.Nm hid_set_data 46.Nd USB HID access routines 47.Sh LIBRARY 48.Lb libusb 49.Sh SYNOPSIS 50.In libusbhid.h 51.Ft report_desc_t 52.Fn hid_get_report_desc "int file" 53.Ft report_desc_t 54.Fn hid_use_report_desc "unsigned char *data" "unsigned int size" 55.Ft void 56.Fn hid_dispose_report_desc "report_desc_t d" 57.Ft hid_data_t 58.Fn hid_start_parse "report_desc_t d" "int kindset" 59.Ft void 60.Fn hid_end_parse "hid_data_t s" 61.Ft int 62.Fn hid_get_item "hid_data_t s" "hid_item_t *h" 63.Ft int 64.Fn hid_report_size "report_desc_t d" "unsigned int id" "hid_kind_t k" 65.Ft int 66.Fn hid_locate "report_desc_t d" "unsigned int usage" "hid_kind_t k" "hid_item_t *h" 67.Ft const char * 68.Fn hid_usage_page "int i" 69.Ft const char * 70.Fn hid_usage_in_page "unsigned int u" 71.Ft int 72.Fn hid_parse_usage_page "const char *name" 73.Ft int 74.Fn hid_parse_usage_in_page "const char *name" 75.Ft void 76.Fn hid_init "const char *file" 77.Ft int 78.Fn hid_get_data "const void *data" "const hid_item_t *h" 79.Ft void 80.Fn hid_set_data "void *p" "const hid_item_t *h" "int data" 81.Sh DESCRIPTION 82The 83.Nm 84library provides routines to extract data from USB Human Interface Devices. 85.Ss INTRODUCTION 86USB HID devices send and receive data layed out in a device dependent 87way. The 88.Nm 89library contains routines to extract the 90.Em report descriptor 91which contains the data layout information and then use this information. 92.Pp 93The routines can be divided into four parts: extraction of the descriptor, 94parsing of the descriptor, translating to/from symbolic names, and 95data manipulation. 96.Ss DESCRIPTOR FUNCTIONS 97A report descriptor can be obtained by calling 98.Fn hid_get_report_desc 99with a file descriptor obtained by opening a 100.Xr uhid 4 101device. Alternatively a data buffer containing the report descriptor can be 102passed into 103.Fn hid_use_report_desc . 104The data is copied into an internal structure. When the report descriptor 105is no longer needed it should be freed by calling 106.Fn hid_dispose_report_desc . 107The type 108.Fa report_desc_t 109is opaque and should be used when calling the parsing functions. 110If 111.Fn hid_dispose_report_desc 112fails it will return 113.Fa NULL . 114.Ss DESCRIPTOR PARSING FUNCTIONS 115To parse the report descriptor the 116.Fn hid_start_parse 117function should be called with a report descriptor and a set that 118describes which items that are interesting. The set is obtained 119by or-ing together values 120.Fa "(1 << k)" 121where 122.Fa k 123is an item of type 124.Fa hid_kind_t . 125The function returns 126.Fa NULL 127if the initialization fails, otherwise an opaque value to be used 128in subsequent calls. 129After parsing the 130.Fn hid_end_parse 131function should be called to free internal data structures. 132.Pp 133To iterate through all the items in the report descriptor 134.Fn hid_get_item 135should be called while it returns a value greater than 0. 136When the report descriptor ends it will returns 0; a syntax 137error within the report descriptor will cause a return value less 138than 0. 139The struct pointed to by 140.Fa h 141will be filled with the relevant data for the item. 142The definition of 143.Fa hid_item_t 144can be found in 145.Pa <libusbhid.h> 146and the meaning of the components in the USB HID documentation. 147.Pp 148Data should be read/written to the device in the size of 149the report. The size of a report (of a certain kind) can be 150computed by the 151.Fn hid_report_size 152function. 153.Pp 154To locate a single item the 155.Fn hid_locate 156function can be used. It should be given the usage code of 157the item and its kind and it will fill the item and return 158non-zero if the item was found. 159.Pp 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). 193.Sh EXAMPLES 194Not yet. 195.Sh FILES 196.Pa /usr/share/misc/usb_hid_usages 197The default HID usage table. 198.Sh BUGS 199This man page is woefully incomplete. 200.Sh SEE ALSO 201The 202.Tn USB 203specifications can be found at 204.Dv http://www.usb.org/developers/docs.htm . 205.Pp 206.Xr uhid 4 , 207.Xr usb 4 208.Sh HISTORY 209The 210.Nm 211library first appeared in 212.Nx 1.5 . 213