summaryrefslogtreecommitdiff
path: root/lib/libusbhid/data.c
blob: 3fcf719e2cee6365000cf7c94937a4cc66e7398c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
/*	$OpenBSD: data.c,v 1.5 2012/07/12 10:17:43 yuo Exp $	*/
/*	$NetBSD: data.c,v 1.1 2001/12/28 17:45:26 augustss Exp $	*/

/*
 * Copyright (c) 1999 Lennart Augustsson <augustss@netbsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdlib.h>
#include "usbhid.h"

int
hid_get_data(const void *p, const hid_item_t *h)
{
	const uint8_t *buf;
	uint32_t hpos, hsize, data;
	int i, end, offs;

	buf = p;

	/* skip report ID byte */
	if (h->report_ID > 0)
		buf++;

	hpos = h->pos;		/* bit position of data */
	hsize = h->report_size;	/* bit length of data */

	if (hsize == 0)
		return (0);
	if (hsize > 32)
		hsize = 32;

	offs = hpos / 8;
	end = (hpos + hsize) / 8 - offs;
	data = 0;
	for (i = 0; i <= end; i++)
		data |= buf[offs + i] << (i*8);

	/* Correctly shift down data */
	data >>= hpos % 8;
	hsize = 32 - hsize;

	/* Mask and sign extend in one */
	if ((h->logical_minimum < 0) || (h->logical_maximum < 0))
		data = (int32_t)((int32_t)data << hsize) >> hsize;
	else
		data = (uint32_t)((uint32_t)data << hsize) >> hsize;

	return (data);
}

void
hid_set_data(void *p, const hid_item_t *h, int data)
{
	uint32_t *buf;
	uint32_t hpos, hsize;
	int i, end, offs, mask;

	buf = p;

	/* Set report ID byte */
	if (h->report_ID > 0)
		*buf++ = h->report_ID & 0xff;

	hpos = h->pos;		/* bit position of data */
	hsize = h->report_size;	/* bit length of data */

	if (hsize != 32) {
		mask = (1 << hsize) - 1;
		data &= mask;
	} else
		mask = ~0;

	data <<= (hpos % 8);
	mask <<= (hpos % 8);
	mask = ~mask;

	offs = hpos / 8;
	end = (hpos + hsize) / 8 - offs;

	for (i = 0; i <= end; i++)
		buf[offs + i] = (buf[offs + i] & (mask >> (i*8))) |
		    ((data >> (i*8)) & 0xff);
}