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data.c revision 1.1 
      1 /*	$NetBSD: data.c,v 1.1 2001/12/28 17:45:26 augustss 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 <assert.h>
     30 #include <stdlib.h>
     31 #include "usbhid.h"
     32 
     33 int
     34 hid_get_data(const void *p, const hid_item_t *h)
     35 {
     36 	const unsigned char *buf;
     37 	unsigned int hpos;
     38 	unsigned int hsize;
     39 	int data;
     40 	int i, end, offs;
     41 
     42 	_DIAGASSERT(p != NULL);
     43 	_DIAGASSERT(h != NULL);
     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 
     66 void
     67 hid_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 	_DIAGASSERT(p != NULL);
     75 	_DIAGASSERT(h != NULL);
     76 
     77 	buf = p;
     78 	hpos = h->pos;			/* bit position of data */
     79 	hsize = h->report_size;		/* bit length of data */
     80 
     81 	if (hsize != 32) {
     82 		mask = (1 << hsize) - 1;
     83 		data &= mask;
     84 	} else
     85 		mask = ~0;
     86 
     87 	data <<= (hpos % 8);
     88 	mask <<= (hpos % 8);
     89 	mask = ~mask;
     90 
     91 	offs = hpos / 8;
     92 	end = (hpos + hsize) / 8 - offs;
     93 
     94 	for (i = 0; i <= end; i++)
     95 		buf[offs + i] = (buf[offs + i] & (mask >> (i*8))) |
     96 			((data >> (i*8)) & 0xff);
     97 }
     98