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data.c revision 1.2 
      1 /*	$NetBSD: data.c,v 1.2 2003/03/08 07:45:57 lukem Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1999 Lennart Augustsson <augustss (at) 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 1.2 2003/03/08 07:45:57 lukem Exp $");
     31 
     32 #include <assert.h>
     33 #include <stdlib.h>
     34 #include "usbhid.h"
     35 
     36 int
     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 	int 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) / 8 - offs;
     56 	data = 0;
     57 	for (i = 0; i <= end; i++)
     58 		data |= buf[offs + i] << (i*8);
     59 	data >>= hpos % 8;
     60 	data &= (1 << hsize) - 1;
     61 	if (h->logical_minimum < 0) {
     62 		/* Need to sign extend */
     63 		hsize = sizeof data * 8 - hsize;
     64 		data = (data << hsize) >> hsize;
     65 	}
     66 	return (data);
     67 }
     68 
     69 void
     70 hid_set_data(void *p, const hid_item_t *h, int data)
     71 {
     72 	unsigned char *buf;
     73 	unsigned int hpos;
     74 	unsigned int hsize;
     75 	int i, end, offs, mask;
     76 
     77 	_DIAGASSERT(p != NULL);
     78 	_DIAGASSERT(h != NULL);
     79 
     80 	buf = p;
     81 	hpos = h->pos;			/* bit position of data */
     82 	hsize = h->report_size;		/* bit length of data */
     83 
     84 	if (hsize != 32) {
     85 		mask = (1 << hsize) - 1;
     86 		data &= mask;
     87 	} else
     88 		mask = ~0;
     89 
     90 	data <<= (hpos % 8);
     91 	mask <<= (hpos % 8);
     92 	mask = ~mask;
     93 
     94 	offs = hpos / 8;
     95 	end = (hpos + hsize) / 8 - offs;
     96 
     97 	for (i = 0; i <= end; i++)
     98 		buf[offs + i] = (buf[offs + i] & (mask >> (i*8))) |
     99 			((data >> (i*8)) & 0xff);
    100 }
    101