/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1992-2001 by Sun Microsystems, Inc.
 * All rights reserved.
 */

#ifndef _MULTIMEDIA_FIR_H
#define _MULTIMEDIA_FIR_H

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Finite Impulse Response (FIR) filter object
 *
 * For every input sample, the FIR filter generates an output sample:
 * output =     coef[0] * input +
 *              coef[1] * state[order - 1] +
 *              coef[2] * state[order - 2] +
 *              ...
 *              coef[order] * state[0]
 *
 * and the filter states are updated:
 *      state[0] = state[1]
 *      state[1] = state[2]
 *      ...
 *      state[order - 2] = state[order - 1]
 *      state[order - 1] = input
 */
class Fir {
protected:
        int             order;          // filter order, # taps = order + 1
        double          *coef;          // (order + 1) filter coeffs.
        double          *state;         // "order" filter states
        int             delay;          // actual delay between output & input

        virtual void    updateState(double *data, int size);
        virtual void    update_short(short *data, int size);
        virtual int     flush(short *out);
public:
        virtual void    resetState(void);       // reset states to zero
        Fir(void);
        Fir(int order_in);
        ~Fir();
        virtual int     getOrder(void);         // get filter order value
        virtual int     getNumCoefs(void);      // get number of coefficients
        virtual void    putCoef(double *coef_in); // put coef_in in filter coef
        virtual void    getCoef(double *coef_out); // get filter coef
        // filter "size" input samples for "size" output samples
        virtual int     filter_noadjust(short *in, int size, short *out);
        /*
         * filter "size" input samples. Output sample sequence is offset by
         * group delay samples to align with the input sample sequence.
         * the first call of this routine returns "size - group_delay"
         * output samples. Call this routine with size = 0
         * to fill the output buffer such that the total number of output
         * samples is equal to the number of input samples.
         */
        virtual int     getFlushSize(void); // size of out[] for the last call
        virtual int     filter(short *in, int size, short *out);
};

#ifdef __cplusplus
}
#endif

#endif /* !_MULTIMEDIA_FIR_H */