/*      $NetBSD: data.c,v 1.9 2020/04/04 21:21:35 fox Exp $     */

/*
* Copyright (c) 1999 Lennart Augustsson <[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__RCSID("$NetBSD: data.c,v 1.9 2020/04/04 21:21:35 fox Exp $");

#include <assert.h>
#include <stdlib.h>
#include "usbhid.h"

int
hid_get_data(const void *p, const hid_item_t *h)
{
       const unsigned char *buf;
       unsigned int hpos;
       unsigned int hsize;
       uint32_t data;
       int i, end, offs;

       _DIAGASSERT(p != NULL);
       _DIAGASSERT(h != NULL);

       buf = p;
       hpos = h->pos;                  /* bit position of data */
       hsize = h->report_size;         /* bit length of data */

       if (hsize == 0)
               return (0);
       offs = hpos / 8;
       end = (hpos + hsize + 7) / 8 - offs;
       data = 0;
       for (i = 0; i < end; i++)
               data |= ((uint32_t)buf[offs + i]) << (i*8);
       data >>= hpos % 8;
       if (hsize < 32) {
               data &= (1 << hsize) - 1;
               if (h->logical_minimum < 0 && (data & (1<<(hsize-1)))) {
                       /* Need to sign extend */
                       data |= 0xffffffff & ~((1<<hsize)-1);
               }
       }
       return (int)(data);
}

void
hid_set_data(void *p, const hid_item_t *h, int data)
{
       unsigned char *buf;
       unsigned int hpos;
       unsigned int hsize;
       int i, end, offs, mask;

       _DIAGASSERT(p != NULL);
       _DIAGASSERT(h != NULL);

       buf = p;
       hpos = h->pos;                  /* bit position of data */
       hsize = h->report_size;         /* bit length of data */

       if (hsize != 32) {
               mask = (1 << hsize) - 1;
               data &= mask;
       } else
               mask = ~0;

       data = ((uint32_t)data) << (hpos % 8);
       mask = ((uint32_t)mask) << (hpos % 8);
       mask = ~mask;

       offs = hpos / 8;
       end = (hpos + hsize) / 8 - offs;

       for (i = 0; i < end; i++)
               buf[offs + i] = (buf[offs + i] & ((uint32_t)mask >> (i*8))) |
                       (((uint32_t)data >> (i*8)) & 0xff);
}