/*
 * SpanDSP - a series of DSP components for telephony
 *
 * private/oki_adpcm.h - Conversion routines between linear 16 bit PCM data
 *                       and OKI (Dialogic) ADPCM format.
 *
 * Written by Steve Underwood <steveu@coppice.org>
 *
 * Copyright (C) 2001 Steve Underwood
 *
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1,
 * as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*! \file */

#if !defined(_SPANDSP_PRIVATE_OKI_ADPCM_H_)
#define _SPANDSP_PRIVATE_OKI_ADPCM_H_

/*!
    Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of
    a single working instance of the Oki ADPCM converter. This is used for
    either linear to ADPCM or ADPCM to linear conversion.
*/
struct oki_adpcm_state_s
{
    /*! \brief The bit rate - 24000 or 32000. */
    int bit_rate;
    /*! \brief The last state of the ADPCM algorithm. */
    int16_t last;
    /*! \brief Current index into the step size table. */
    int16_t step_index;
    /*! \brief The compressed data byte in progress. */
    uint8_t oki_byte;
    /*! \brief The signal history for the sample rate converter. */
    int16_t history[32];
    /*! \brief Pointer into the history buffer. */
    int ptr;
    /*! \brief Odd/even sample counter. */
    int mark;
    /*! \brief Phase accumulator for the sample rate converter. */
    int phase;
};

#endif
/*- End of file ------------------------------------------------------------*/