lib/libusbhid/data.c

   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: src/lib/libusbhid/data.c,v 1.5.2.1 2002/04/03 15:54:00 joe Exp $
  29  * $DragonFly: src/lib/libusbhid/data.c,v 1.2 2003/06/17 04:26:51 dillon Exp $
  30  */
  31
  32 #include <assert.h>
  33 #include <stdlib.h>
  34 #include "libusbhid.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         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         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 }