usr/src/cmd/audio/include/Fir.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 1992-2001 by Sun Microsystems, Inc.
  24  * All rights reserved.
  25  */
  26
  27 #ifndef _MULTIMEDIA_FIR_H
  28 #define _MULTIMEDIA_FIR_H
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 /*
  37  * Finite Impulse Response (FIR) filter object
  38  *
  39  * For every input sample, the FIR filter generates an output sample:
  40  * output =     coef[0] * input +
  41  *              coef[1] * state[order - 1] +
  42  *              coef[2] * state[order - 2] +
  43  *              ...
  44  *              coef[order] * state[0]
  45  *
  46  * and the filter states are updated:
  47  *      state[0] = state[1]
  48  *      state[1] = state[2]
  49  *      ...
  50  *      state[order - 2] = state[order - 1]
  51  *      state[order - 1] = input
  52  */
  53 class Fir {
  54 protected:
  55         int             order;          // filter order, # taps = order + 1
  56         double          *coef;          // (order + 1) filter coeffs.
  57         double          *state;         // "order" filter states
  58         int             delay;          // actual delay between output & input
  59
  60         virtual void    updateState(double *data, int size);
  61         virtual void    update_short(short *data, int size);
  62         virtual int     flush(short *out);
  63 public:
  64         virtual void    resetState(void);       // reset states to zero
  65         Fir(void);
  66         Fir(int order_in);
  67         ~Fir();
  68         virtual int     getOrder(void);         // get filter order value
  69         virtual int     getNumCoefs(void);      // get number of coefficients
  70         virtual void    putCoef(double *coef_in); // put coef_in in filter coef
  71         virtual void    getCoef(double *coef_out); // get filter coef
  72         // filter "size" input samples for "size" output samples
  73         virtual int     filter_noadjust(short *in, int size, short *out);
  74         /*
  75          * filter "size" input samples. Output sample sequence is offset by
  76          * group delay samples to align with the input sample sequence.
  77          * the first call of this routine returns "size - group_delay"
  78          * output samples. Call this routine with size = 0
  79          * to fill the output buffer such that the total number of output
  80          * samples is equal to the number of input samples.
  81          */
  82         virtual int     getFlushSize(void); // size of out[] for the last call
  83         virtual int     filter(short *in, int size, short *out);
  84 };
  85
  86 #ifdef __cplusplus
  87 }
  88 #endif
  89
  90 #endif /* !_MULTIMEDIA_FIR_H */