data.c revision 93282 
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
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: head/lib/libusbhid/data.c 84224 2001-09-30 22:30:55Z dillon $");
31
32#include <assert.h>
33#include <stdlib.h>
34#include "libusb.h"
35
36int
37hid_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	int data;
43	int i, end, offs;
44
45	buf = p;
46	hpos = h->pos;			/* bit position of data */
47	hsize = h->report_size;		/* bit length of data */
48
49	if (hsize == 0)
50		return (0);
51	offs = hpos / 8;
52	end = (hpos + hsize) / 8 - offs;
53	data = 0;
54	for (i = 0; i <= end; i++)
55		data |= buf[offs + i] << (i*8);
56	data >>= hpos % 8;
57	data &= (1 << hsize) - 1;
58	if (h->logical_minimum < 0) {
59		/* Need to sign extend */
60		hsize = sizeof data * 8 - hsize;
61		data = (data << hsize) >> hsize;
62	}
63	return (data);
64}
65
66void
67hid_set_data(void *p, const hid_item_t *h, int data)
68{
69	unsigned char *buf;
70	unsigned int hpos;
71	unsigned int hsize;
72	int i, end, offs, mask;
73
74	buf = p;
75	hpos = h->pos;			/* bit position of data */
76	hsize = h->report_size;		/* bit length of data */
77
78	if (hsize != 32) {
79		mask = (1 << hsize) - 1;
80		data &= mask;
81	} else
82		mask = ~0;
83
84	data <<= (hpos % 8);
85	mask <<= (hpos % 8);
86	mask = ~mask;
87
88	offs = hpos / 8;
89	end = (hpos + hsize) / 8 - offs;
90
91	for (i = 0; i <= end; i++)
92		buf[offs + i] = (buf[offs + i] & (mask >> (i*8))) |
93			((data >> (i*8)) & 0xff);
94}
95