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34 .Nm hid_get_report_desc ,
35 .Nm hid_use_report_desc ,
36 .Nm hid_dispose_report_desc ,
43 .Nm hid_usage_in_page ,
47 .Nd USB HID access routines
53 .Fn hid_get_report_desc "int file"
55 .Fn hid_use_report_desc "unsigned char *data" "unsigned int size"
57 .Fn hid_dispose_report_desc "report_desc_t d"
59 .Fn hid_start_parse "report_desc_t d" "int kindset" "int id"
61 .Fn hid_end_parse "hid_data_t s"
63 .Fn hid_get_item "hid_data_t s" "hid_item_t *h"
65 .Fn hid_report_size "report_desc_t d" "hid_kind_t k" "int id"
67 .Fn hid_locate "report_desc_t d" "u_int usage" "hid_kind_t k" "hid_item_t *h" "int id"
69 .Fn hid_usage_page "int i"
71 .Fn hid_usage_in_page "u_int u"
73 .Fn hid_parse_usage_page "const char *"
75 .Fn hid_parse_usage_in_page "const char *"
77 .Fn hid_init "const char *file"
79 .Fn hid_get_data "const void *data" "const hid_item_t *h"
81 .Fn hid_set_data "void *buf" "const hid_item_t *h" "int data"
85 library provides routines to extract data from USB Human Interface Devices.
87 USB HID devices send and receive data layed out in a device dependent way.
90 library contains routines to extract the
91 .Em "report descriptor"
92 which contains the data layout information and then use this information.
94 The routines can be divided into four parts: extraction of the descriptor,
95 parsing of the descriptor, translating to/from symbolic names, and
97 .Ss Descriptor Functions
98 A report descriptor can be obtained by calling
99 .Fn hid_get_report_desc
100 with a file descriptor obtained by opening a
103 Alternatively a data buffer containing the report descriptor can be
105 .Fn hid_use_report_desc .
106 The data is copied into an internal structure.
107 When the report descriptor
108 is no longer needed it should be freed by calling
109 .Fn hid_dispose_report_desc .
112 is opaque and should be used when calling the parsing functions.
114 .Fn hid_dispose_report_desc
117 .Ss Descriptor Parsing Functions
118 To parse the report descriptor the
120 function should be called with a report descriptor and a set that
121 describes which items that are interesting.
122 The set is obtained by OR-ing together values
128 The report ID (if present) is given by
132 if the initialization fails, otherwise an opaque value to be used
136 function should be called to free internal data structures.
138 To iterate through all the items in the report descriptor
140 should be called while it returns a value greater than 0.
141 When the report descriptor ends it will returns 0; a syntax
142 error within the report descriptor will cause a return value less
144 The struct pointed to by
146 will be filled with the relevant data for the item.
151 and the meaning of the components in the USB HID documentation.
153 Data should be read/written to the device in the size of
155 The size of a report (of a certain kind) can be computed by the
158 If the report is prefixed by an ID byte it is given by
161 To locate a single item the
163 function can be used.
164 It should be given the usage code of
165 the item and its kind and it will fill the item and return
166 non-zero if the item was found.
167 .Ss Name Translation Functions
170 will return the symbolic name of a usage page, and the function
171 .Fn hid_usage_in_page
172 will return the symbolic name of the usage within the page.
173 Both these functions may return a pointer to static data.
176 .Fn hid_parse_usage_page
178 .Fn hid_parse_usage_in_page
182 .Fn hid_usage_in_page .
183 They take a usage string and return the number of the usage, or \-1
184 if it cannot be found.
186 Before any of these functions can be called the usage table
187 must be parsed, this is done by calling
189 with the name of the table.
192 to this function will cause it to use the default table.
193 .Ss Data Extraction Functions
194 Given the data obtained from a HID device and an item in the
195 report descriptor the
197 function extracts the value of the item.
200 can be used to put data into a report (which must be zeroed first).
202 .Bl -tag -width ".Pa /usr/share/misc/usb_hid_usages"
203 .It Pa /usr/share/misc/usb_hid_usages
204 The default HID usage table.
211 specifications can be found at
212 .Pa http://www.usb.org/developers/docs/ .
219 library first appeared in
222 This man page is woefully incomplete.