1 /*        $NetBSD: data.c,v 1.9 2020/04/04 21:21:35 fox Exp $         */
2 
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 
29 #include <sys/cdefs.h>
30 __RCSID("$NetBSD: data.c,v 1.9 2020/04/04 21:21:35 fox Exp $");
31 
32 #include <assert.h>
33 #include <stdlib.h>
34 #include "usbhid.h"
35 
36 int
hid_get_data(const void * p,const hid_item_t * h)37 hid_get_data(const void *p, const hid_item_t *h)
38 {
39           const unsigned char *buf;
40           unsigned int hpos;
41           unsigned int hsize;
42           uint32_t data;
43           int i, end, offs;
44 
45           _DIAGASSERT(p != NULL);
46           _DIAGASSERT(h != NULL);
47 
48           buf = p;
49           hpos = h->pos;                          /* bit position of data */
50           hsize = h->report_size;                 /* bit length of data */
51 
52           if (hsize == 0)
53                     return (0);
54           offs = hpos / 8;
55           end = (hpos + hsize + 7) / 8 - offs;
56           data = 0;
57           for (i = 0; i < end; i++)
58                     data |= ((uint32_t)buf[offs + i]) << (i*8);
59           data >>= hpos % 8;
60           if (hsize < 32) {
61                     data &= (1 << hsize) - 1;
62                     if (h->logical_minimum < 0 && (data & (1<<(hsize-1)))) {
63                               /* Need to sign extend */
64                               data |= 0xffffffff & ~((1<<hsize)-1);
65                     }
66           }
67           return (int)(data);
68 }
69 
70 void
hid_set_data(void * p,const hid_item_t * h,int data)71 hid_set_data(void *p, const hid_item_t *h, int data)
72 {
73           unsigned char *buf;
74           unsigned int hpos;
75           unsigned int hsize;
76           int i, end, offs, mask;
77 
78           _DIAGASSERT(p != NULL);
79           _DIAGASSERT(h != NULL);
80 
81           buf = p;
82           hpos = h->pos;                          /* bit position of data */
83           hsize = h->report_size;                 /* bit length of data */
84 
85           if (hsize != 32) {
86                     mask = (1 << hsize) - 1;
87                     data &= mask;
88           } else
89                     mask = ~0;
90 
91           data = ((uint32_t)data) << (hpos % 8);
92           mask = ((uint32_t)mask) << (hpos % 8);
93           mask = ~mask;
94 
95           offs = hpos / 8;
96           end = (hpos + hsize) / 8 - offs;
97 
98           for (i = 0; i < end; i++)
99                     buf[offs + i] = (buf[offs + i] & ((uint32_t)mask >> (i*8))) |
100                               (((uint32_t)data >> (i*8)) & 0xff);
101 }
102