/*      $OpenBSD: data.c,v 1.8 2014/06/04 12:13:30 mpi Exp $    */
/*      $NetBSD: data.c,v 1.1 2001/12/28 17:45:26 augustss Exp $        */

/*
 * Copyright (c) 1999 Lennart Augustsson <augustss@netbsd.org>
 * 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 <stdlib.h>
#include "usbhid.h"

int32_t
hid_get_data(const void *p, const hid_item_t *h)
{
        const uint8_t *buf;
        uint32_t hpos;
        uint32_t hsize;
        uint32_t data;
        int i, end, offs;

        buf = p;

#if 0
        /* Skip report ID byte. */
        if (h->report_ID > 0)
                buf++;
#endif

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

        /* Range check and limit */
        if (hsize == 0)
                return (0);
        if (hsize > 32)
                hsize = 32;

        offs = hpos / 8;
        end = (hpos + hsize) / 8 - offs;
        data = 0;
        for (i = 0; i <= end; i++)
                data |= buf[offs + i] << (i*8);

        /* Correctly shift down data */
        data >>= hpos % 8;
        hsize = 32 - hsize;

        /* Mask and sign extend in one */
        if ((h->logical_minimum < 0) || (h->logical_maximum < 0))
                data = (int32_t)((int32_t)data << hsize) >> hsize;
        else
                data = (uint32_t)((uint32_t)data << hsize) >> hsize;

        return (data);
}

void
hid_set_data(void *p, const hid_item_t *h, int32_t data)
{
        uint8_t *buf;
        uint32_t hpos;
        uint32_t hsize;
        uint32_t mask;
        int i;
        int end;
        int offs;

        buf = p;

#if 0
        /* Set report ID byte. */
        if (h->report_ID > 0)
                *buf++ = h->report_ID & 0xff;
#endif

        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 <<= (hpos % 8);
        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] & (mask >> (i*8))) |
                    ((data >> (i*8)) & 0xff);
}