/*
 * filters.h
 *
 * Description:  TTAv1 filter functions
 * Developed by: Alexander Djourik <sasha@iszf.irk.ru>
 *               Pavel Zhilin <pzh@iszf.irk.ru>
 *
 * Copyright (c) 1999-2004 Alexander Djourik. All rights reserved.
 *
 */

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * aint with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please see the file COPYING in this directory for full copyright
 * information.
 */

#ifndef FILTERS_H
#define FILTERS_H

///////// Filter Settings //////////
static const long flt_set[3] = {10, 9, 10};

static void
memshl (register long *pA, register long *pB) {
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA++ = *pB++;
        *pA   = *pB;
}

static void
hybrid_filter (fltst *fs, long *in) {
        register long *pA = fs->dl;
        register long *pB = fs->qm;
        register long *pM = fs->dx;
        register long sum = fs->round;

        if (!fs->error) {
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++;
                sum += *pA++ * *pB, pB++; pM += 8;
        } else if (fs->error < 0) {
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
                sum += *pA++ * (*pB -= *pM++), pB++;
        } else {
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
                sum += *pA++ * (*pB += *pM++), pB++;
        }

        *(pM-0) = ((*(pA-1) >> 30) | 1) << 2;
        *(pM-1) = ((*(pA-2) >> 30) | 1) << 1;
        *(pM-2) = ((*(pA-3) >> 30) | 1) << 1;
        *(pM-3) = ((*(pA-4) >> 30) | 1);

        fs->error = *in;
        *in += (sum >> fs->shift);
        *pA = *in;

        *(pA-1) = *(pA-0) - *(pA-1);
        *(pA-2) = *(pA-1) - *(pA-2);
        *(pA-3) = *(pA-2) - *(pA-3);

        memshl (fs->dl, fs->dl + 1);
        memshl (fs->dx, fs->dx + 1);
}

static void
filter_init (fltst *fs, long shift) {
        memset (fs, 0, sizeof(fltst));
        fs->shift = shift;
        fs->round = 1 << (shift - 1);
}

#endif  /* FILTERS_H */