lib/libusbhid/data.c

   1 /*      $NetBSD: data.c,v 1.4 2005/12/05 02:09:17 christos 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 __RCSID("$NetBSD: data.c,v 1.4 2005/12/05 02:09:17 christos 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         uint32_t 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 && (data & (1<<(hsize-1)))) {
  62                 /* Need to sign extend */
  63                 data |= 0xffffffff & ~((1<<hsize)-1);
  64         }
  65         return (int)(data);
  66 }
  67
  68 void
  69 hid_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] & ((uint32_t)mask >> (i*8))) |
  98                         (((uint32_t)data >> (i*8)) & 0xff);
  99 }