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filter.h

/*
 * Copyright (c) 1991-1993 Regents of the University of California.
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the Computer Systems
 *    Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 * @(#) $Header: filter.h,v 1.2 93/01/25 15:30:15 mccanne Exp $ (LBL)
 */

class Filter;
class FilterTap;

#ifndef vat_filter_h
#define vat_filter_h

#include "ss.h"
#include "audio.h"

/*
 * We do as much precomputation as possible for each filter tap.
 * The product field is a table of precomputed products of the filter
 * coefficient (which is not actually stored) with each of the possible
 * 256 ulaw encoded values.  The values are stored as linear 32 bit fixed 
 * point numbers (16 bits of fraction).  The tapno field gives the
 * power of 1/z.
 */
struct FilterTap {
      double mod;
      int tapno;
      int product[256];
};

class Filter {
    public:
      Filter(Audio *);
      ~Filter();
      void Create(double *, int, int);
      void Compute(SampleStream *, u_char *, int);
      void Train(int, int);
    private:
      int ntaps;
      Audio *audio;
      FilterTap *taps;
};

#endif

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