data.c revision 61560 
1/*	$NetBSD: data.c,v 1.8 2000/04/02 11:10:53 augustss 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 * $FreeBSD: head/lib/libusbhid/data.c 61560 2000-06-11 18:19:14Z n_hibma $
29 */
30
31#include <assert.h>
32#include <stdlib.h>
33#include "libusb.h"
34
35int
36hid_get_data(const void *p, const hid_item_t *h)
37{
38	const unsigned char *buf;
39	unsigned int hpos;
40	unsigned int hsize;
41	int data;
42	int i, end, offs;
43
44	_DIAGASSERT(p != NULL);
45	_DIAGASSERT(h != NULL);
46
47	buf = p;
48	hpos = h->pos;			/* bit position of data */
49	hsize = h->report_size;		/* bit length of data */
50
51	if (hsize == 0)
52		return (0);
53	offs = hpos / 8;
54	end = (hpos + hsize) / 8 - offs;
55	data = 0;
56	for (i = 0; i <= end; i++)
57		data |= buf[offs + i] << (i*8);
58	data >>= hpos % 8;
59	data &= (1 << hsize) - 1;
60	if (h->logical_minimum < 0) {
61		/* Need to sign extend */
62		hsize = sizeof data * 8 - hsize;
63		data = (data << hsize) >> hsize;
64	}
65	return (data);
66}
67
68void
69hid_set_data(void *p, const hid_item_t *h, int data)
70{
71	unsigned char *buf;
72	unsigned int hpos;
73	unsigned int hsize;
74	int i, end, offs, mask;
75
76	_DIAGASSERT(p != NULL);
77	_DIAGASSERT(h != NULL);
78
79	buf = p;
80	hpos = h->pos;			/* bit position of data */
81	hsize = h->report_size;		/* bit length of data */
82
83	if (hsize != 32) {
84		mask = (1 << hsize) - 1;
85		data &= mask;
86	} else
87		mask = ~0;
88
89	data <<= (hpos % 8);
90	mask <<= (hpos % 8);
91	mask = ~mask;
92
93	offs = hpos / 8;
94	end = (hpos + hsize) / 8 - offs;
95
96	for (i = 0; i <= end; i++)
97		buf[offs + i] = (buf[offs + i] & (mask >> (i*8))) |
98			((data >> (i*8)) & 0xff);
99}
100