filter.h

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/*
 * filter.h
 *
 * Description:	 TTAv1 filter functions
 * Developed by: Alexander Djourik <[e-mail]>
 *               Pavel Zhilin <[e-mail]>
 *
 * Copyright (c) 2004 True Audio Software. 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.
 * 3. Neither the name of the True Audio Software nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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.
 */

#ifndef FILTER_H
#define FILTER_H

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

__inline void
memshl (register int *pA, register int *pB) {
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA++ = *pB++;
	*pA   = *pB;
}

__inline void
hybrid_filter (fltst *fs, int *in) {
	register int *pA = fs->dl;
	register int *pB = fs->qm;
	register int *pM = fs->dx;
	register int 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);
}

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

#endif	/* FILTER_H */