/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* ====================================================================
 * Copyright (c) 1999-2001 Carnegie Mellon University.  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.
 *
 * This work was supported in part by funding from the Defense Advanced 
 * Research Projects Agency and the National Science Foundation of the 
 * United States of America, and the CMU Sphinx Speech Consortium.
 *
 * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND 
 * ANY EXPRESSED 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 CARNEGIE MELLON UNIVERSITY
 * NOR ITS EMPLOYEES 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.
 *
 * ====================================================================
 *
 */
/*
 * cont_ad.c -- Continuous A/D listening and silence filtering module.
 * 
 * HISTORY
 * 
 * $Log: cont_ad_base.c,v $
 * Revision 1.14  2005/07/02 03:51:32  rkm
 * Slowed down power histogram decay rate
 *
 * Revision 1.13  2005/06/30 00:27:17  rkm
 * Fixed silence handling in rawmode; added extra state variables
 *
 * 
 * 28-Jun-2005	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University.
 *		- Changed rawmode handling to simply copy data even for silence
 * 		segments.
 * 		- Moved definitions of CONT_AD_STATE_{SIL,SPEECH} from .c to .h.
 * 
 * Revision 1.12  2005/06/29 23:48:04  egouvea
 * Revert changes: variables defined in cont_ad_base.c should not be accessible by the application
 *
 * Revision 1.10  2005/02/13 01:29:48  rkm
 * Fixed cont_ad_read to never cross sil/speech boundary, and rawmode
 *
 * Revision 1.9  2005/02/01 22:21:19  rkm
 * Added raw data logging, and raw data pass-through mode to cont_ad
 *
 * Revision 1.8  2004/07/23 23:36:34  egouvea
 * Ravi's merge, with the latest fixes in the FSG code, and making the log files generated by FSG, LM, and allphone have the same 'look and feel', with the backtrace information presented consistently
 *
 * 23-Jul-2004	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Changed default adapt_rate from 0.5 to 0.2.
 *
 * Revision 1.7  2004/07/16 00:57:12  egouvea
 * Added Ravi's implementation of FSG support.
 *
 * Revision 1.2  2004/06/23 20:31:18  rkm
 * Added adapt_rate parameter; restructured frame processing to include threshold update
 *
 * 
 * 23-Oct-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Small change in the way the noiselevel is updated in find_thresh().
 * 
 * 26-Aug-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Separated computation of "frame power" into a separate low-level
 * 		function.
 * 
 * 13-Jul-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Modified to allow frame size to depend on audio sampling rate.
 * 
 * 01-Jul-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Changed CONT_AD_DELTA_SPEECH back to 20.
 * 
 * 30-Jun-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Changed CONT_AD_DELTA_SPEECH from 10 to 15.
 * 		Added FILE* argument to cont_ad_powhist_dump().
 * 
 * 19-Jun-98	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Changed CONT_AD_DELTA_SPEECH from 20 to 10, to increase sensitivity
 * 		to very short utterances.
 * 
 * 16-Jan-98	Paul Placeway (pwp@cs.cmu.edu) at Carnegie Mellon University
 * 		Changed to use dB instead of the weird power measure.
 * 		Changed analysis window size, tuned default settings of most
 * 		parameters to make the system less sensitive to noise, changed
 * 		the histogram update frequency and decay to make the system
 * 		adapt more rapidly to changes in the environment.
 * 		Added cont_ad_set_params() and cont_ad_get_params().
 * 
 * 28-Jul-96	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Added FRMPOW2SIGLVL, max_siglvl(), and cont_ad_t.siglvl.
 * 		Changed min signal energy/frame to CONT_AD_SPF.
 * 
 * 27-Jun-96	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Added the option for cont_ad_read to return -1 on EOF.
 * 
 * 21-Jun-96	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Added cont_ad_set_thresh().
 * 		Bugfix: n_other is recomputed after updating thresholds.
 * 
 * 20-Jun-96	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Separated thresholds for speech and silence.
 * 		Fixed bug in moving analysis window upon transition to speech state.
 * 
 * 17-Jun-96	M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
 * 		Created, based loosely on Steve Reed's original implementation.
 */

/*
 * This module is intended to be interposed as a filter between any raw A/D source and the
 * application to remove silence regions.  It is initialized with a raw A/D source function
 * (during the cont_ad_init call).  Filtered A/D data can be read by the application using
 * the cont_ad_read function.  This module assumes that the A/D source function supplies an
 * endless stream of data.  The application is responsible for setting up the A/D source,
 * turning recording on and off as it desires.  It is also responsible for invoking the
 * cont_ad_read function frequently enough to avoid buffer overruns and dropping A/D data.
 * This continuous listening module has an internal buffer of about 4 sec.
 * 
 * This module must be initialized and calibrated at first (cont_ad_init and cont_ad_calib
 * functions).  Raw samples are grouped into frames, the signal power in each frame is
 * computed and accumulated in a histogram.  The module is always in one of two states:
 * SILENCE or SPEECH.  Transitions between the two states are detected by looking for a
 * contiguous window of several frames that is predominantly of the other type.  The type
 * is determined by comparing frame power to either of two thresholds, thresh_sil and
 * thresh_speech, as appropriate for the current state.  These thresholds are set from the
 * first peak in the low-end of the power histogram, and are updated every few seconds.
 * Separate thresholds are used to provide some hysteresis.
 * 
 * The module maintains a linked list of speech (non-silence) segments not yet read by the
 * application.  The cont_ad_read function returns speech data, if any available, by
 * following this list.  It also updates an "absolute" timestamp at the end of the
 * cont_ad_read operation.  The timestamp indicates the total #samples of A/D data read
 * until this point, including data discarded as silence frames.  The application is
 * responsible for using this timestamp to make any policy decisions regarding utterance
 * boundaries or whatever.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <math.h>

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifdef _WIN32
#pragma warning (disable: 4305)
#endif

#include "prim_type.h"
#include "ad.h"
#include "cont_ad.h"
#include "err.h"


#ifndef _ABS
#define _ABS(x) ((x) >= 0 ? (x) : -(x))
#endif


/* Various parameters, including defaults for many cont_ad_t member variables */

#define CONT_AD_ADFRMSIZE	256     /* #Frames of internal A/D buffer maintained */

#define CONT_AD_POWHISTSIZE	98      /* #Powhist bins: ~ FRMPOW(65536^2*CONT_AD_SPF) */
/* Maximum level is 96.3 dB full-scale; 97 for safety, plus 1 for zero-based */

#define CONT_AD_THRESH_UPDATE	100     /* Update thresholds approx every so many frames */
        /* PWP: update was 200 frames, or 3.2 seconds.  Now about every 1.6 sec. */

#define CONT_AD_ADAPT_RATE	0.2     /* Interpolation of new and old noiselevel */

#define CONT_AD_SPS             16000

#define CONT_AD_DEFAULT_NOISE	30      /* Default background noise power level */
#define CONT_AD_DELTA_SIL	10      /* Initial default for cont_ad_t.delta_sil */
#define CONT_AD_DELTA_SPEECH	17      /* Initial default for cont_ad_t.delta_speech */
#define CONT_AD_MIN_NOISE	2       /* Expected minimum background noise level */
#define CONT_AD_MAX_NOISE	70      /* Maximum background noise level */

#define CONT_AD_HIST_INERTIA	3       /* Used in decaying the power histogram */

#define CONT_AD_WINSIZE		21      /* Analysis window for state transitions */
                                /* rkm had 16 */

#define CONT_AD_SPEECH_ONSET	9       /* Min #speech frames in analysis window for
                                           SILENCE -> SPEECH state transition */
/*
 * SReed had 100 ms == 6.25 fr contiguous; rkm had 9 (out of 16+10) with a
 * lower threshold.
 */

#define CONT_AD_SIL_ONSET	18      /* Min #silence frames in analysis window for
                                           SPEECH -> SILENCE state transition
                                           MUST BE <= CONT_AD_WINSIZE */
/*
 * SReed had 400 ms == 25 fr contiguous; rkm had 14 out of 16
 */

#define CONT_AD_LEADER		5       /* On transition to SPEECH state, so many frames
                                           BEFORE window included in speech data (>0) */
                                /* SReed had 200 ms == 12.5 fr; rkm had 5 */

#define CONT_AD_TRAILER		10      /* On transition to SILENCE state, so many frames
                                           of silence included in speech data (>0).
                                           NOTE: Ensure (0 < TRAILER+LEADER <= WINSIZE) */
                                /* SReed had 100 ms == 6.25 fr; rkm had 10 */


void
cont_ad_powhist_dump(FILE * fp, cont_ad_t * r)
{
    int32 i, j;

    fprintf(fp, "PowHist:\n");
    for (i = 0, j = 0; i < CONT_AD_POWHISTSIZE; i++) {
        if (r->pow_hist[i] > 0) {
            fprintf(fp, "\t%3d %6d\n", i, r->pow_hist[i]);
            j = i;
        }
    }

    fprintf(fp, "PH[%7.2f]:",
            (double) (r->tot_frm * r->spf) / (double) (r->sps));
    for (i = 0; i <= j; i++)
        fprintf(fp, " %2d", r->pow_hist[i]);
    fprintf(fp, "\n");

    fflush(fp);
}


/*
 * Compute frame power.  Interface deliberately kept low level to allow arbitrary
 * users to call this function with appropriate data.
 */
int32
cont_ad_frame_pow(int16 * buf, int32 * prev, int32 spf)
{
    double sumsq, v;
    int32 i;
    int32 p;

    sumsq = 0.0;
    p = *prev;
    for (i = 0; i < spf; i++) {
        v = (double) (buf[i] - p);
        sumsq += v * v;
        p = buf[i];
    }
    *prev = p;

    if (sumsq < spf)            /* Make sure FRMPOW(sumsq) >= 0 */
        sumsq = spf;

    /*
     * PWP: Units changed to dB
     *
     * Now the units of measurement of an input sample are volts (really!),
     * so the power in dB is p = 20*log10(samp).  Further, we want the RMS
     * (root-mean-squared) average power across the frame.
     *
     * "sumsq" is the sum of the sum of the squares, so we want
     *
     *   i = 20 * log10( sqrt ( sumsq / n_samps) )
     *
     * (Stephen Reed's code actually had 
     *    i = 20 * log10( sqrt (sumsq) / n_samps )
     *  but this only produced an additive error.)
     *
     * i = 20 * log10( sqrt ( sumsq / n_samps) )
     *   = 20 * log10( ( sumsq / n_samps) ^ 0.5 )
     *   = 20 * log10( ( sumsq / n_samps) ) * 0.5 )
     *   = 10 * log10( ( sumsq / n_samps) )
     *   = 10 * ( log10( sumsq) - log10(n_samps) )
     */
    i = (int32) ((10.0 * (log10(sumsq) - log10((double) spf))) + 0.5);
    if (i < 0)
        i = 0;                  /* trim lower bound again to be safe. */
    assert(i < 97);

    return (i);
}


/*
 * Classify frame (id=frm, starting at sample position s) as sil/nonsil.  Classification
 * done in isolation, independent of any other frame, based only on power histogram.
 */
static void
compute_frame_pow(cont_ad_t * r, int32 frm)
{
    int32 i;

    i = cont_ad_frame_pow(r->adbuf + (frm * r->spf), &(r->prev_sample),
                          r->spf);

    r->frm_pow[frm] = (char) i;
    (r->pow_hist[i])++;
    r->thresh_update--;
}


/* PWP: $$$ check this */
/*
 * PWP: in SReed's code, decay was done by zeroing the histogram,
 * i.e. no history.
 */
static void
decay_hist(cont_ad_t * r)
{
    int32 i;

    for (i = 0; i < CONT_AD_POWHISTSIZE; i++)
        r->pow_hist[i] -= (r->pow_hist[i] >> CONT_AD_HIST_INERTIA);
}


/*
 * Find silence threshold from power histogram.
 */
static int32
find_thresh(cont_ad_t * r)
{
    int32 i, j, max, th;
    int32 old_noise_level, old_thresh_sil, old_thresh_speech;

    if (!r->auto_thresh)
        return 0;

    /*
     * Find smallest non-zero histogram entry, but starting at some minimum power.
     * Power lower than CONT_AD_MIN_NOISE indicates bad A/D input (eg, mic off...).
     * Too high a minimum power is also bad.
     */
    for (i = r->min_noise;
         (i < CONT_AD_POWHISTSIZE) && (r->pow_hist[i] == 0); i++);
    if (i > r->max_noise)       /* Bad signal? */
        return -1;

    /* PWP: Hmmmmm.... SReed's code looks over the lower 20 dB */
    /* PWP: 1/14/98  Made to work like Stephen Reed's code */

    /* This method of detecting the noise level is VERY unsatisfactory */
    max = 0;
    for (j = i, th = i; (j < CONT_AD_POWHISTSIZE) && (j < i + 20); j++) {       /* PWP: was i+6, which was 9 dB */
        if (max < r->pow_hist[j]) {
            max = r->pow_hist[j];
            th = j;
        }
    }

    /* "Don't change the threshold too fast" */
    old_noise_level = r->noise_level;
    old_thresh_sil = r->thresh_sil;
    old_thresh_speech = r->thresh_speech;
#if 0
    if (_ABS(r->noise_level - th) >= 10) {
        if (th > r->noise_level)
            r->noise_level += ((th - r->noise_level) / 2);
        else
            r->noise_level -= ((r->noise_level - th) / 2);
    }
    else {
        r->noise_level = th;
    }
#else
    /*
     * RKM: The above is odd; if (diff >= 10) += diff/2; else += diff??
     * This is discontinuous.  Instead, adapt based on the adapt_rate parameter.
     */
    /* r->noise_level = (int32) (th * r->adapt_rate + r->noise_level * (1.0 - r->adapt_rate)); */
    r->noise_level =
        (int32) (r->noise_level +
                 r->adapt_rate * (th - r->noise_level) + 0.5);
#endif

    /* update thresholds */
    r->thresh_sil = r->noise_level + r->delta_sil;
    r->thresh_speech = r->noise_level + r->delta_speech;

    if (r->logfp) {
        fprintf(r->logfp,
                "%7.2fs %8df: NoisePeak: %d, Noiselevel: %d -> %d, Th-Sil: %d -> %d, Th-Sp: %d -> %d\n",
                (double) (r->tot_frm * r->spf) / (double) (r->sps),
                r->tot_frm, th, old_noise_level, r->noise_level,
                old_thresh_sil, r->thresh_sil, old_thresh_speech,
                r->thresh_speech);

        cont_ad_powhist_dump(r->logfp, r);

        fflush(r->logfp);
    }

    /*
     * PWP: in SReed's original, he cleared the histogram here.
     * I can't fathom why.
     */

    return 0;
}


/*
 * Main silence/speech region detection routine.  If currently in
 * SILENCE state, switch to SPEECH state if a window (r->winsize)
 * of frames is mostly non-silence.  If in SPEECH state, switch to
 * SILENCE state if the window is mostly silence.
 */
static void
boundary_detect(cont_ad_t * r, int32 frm)
{
    spseg_t *seg;
    int32 f;

    assert(r->n_other >= 0);

    r->win_validfrm++;
    if (r->tail_state == CONT_AD_STATE_SIL) {
        if (r->frm_pow[frm] >= r->thresh_speech)
            r->n_other++;
    }
    else {
        if (r->frm_pow[frm] <= r->thresh_sil)
            r->n_other++;
    }

    if (r->logfp) {
        fprintf(r->logfp,
                "%7.2fs %8d[%3d]f: P: %2d, N: %2d, T+: %2d, T-: %2d, #O: %2d, %s\n",
                (double) (r->tot_frm * r->spf) / (double) (r->sps),
                r->tot_frm, frm, r->frm_pow[frm], r->noise_level,
                r->thresh_speech, r->thresh_sil, r->n_other,
                (r->tail_state == CONT_AD_STATE_SIL) ? "--" : "Sp");
    }

    if (r->win_validfrm < r->winsize)   /* Not reached full analysis window size */
        return;
    assert(r->win_validfrm == r->winsize);

    if (r->tail_state == CONT_AD_STATE_SIL) {   /* Currently in SILENCE state */
        if (r->n_frm >= r->winsize + r->leader) {
            if (r->n_other >= r->speech_onset) {
                /* Speech detected; create speech segment description */
                seg = malloc(sizeof(*seg));

                seg->startfrm = r->win_startfrm - r->leader;
                if (seg->startfrm < 0)
                    seg->startfrm += CONT_AD_ADFRMSIZE;
                seg->nfrm = r->leader + r->winsize;
                seg->next = NULL;

                if (!r->spseg_head)
                    r->spseg_head = seg;
                else
                    r->spseg_tail->next = seg;
                r->spseg_tail = seg;

                r->tail_state = CONT_AD_STATE_SPEECH;

                if (r->logfp) {
                    int32 n;

                    /* Where (in absolute time) this speech segment starts */
                    n = frm - seg->startfrm;
                    if (n < 0)
                        n += CONT_AD_ADFRMSIZE;
                    n = r->tot_frm - n - 1;

                    fprintf(r->logfp,
                            "%7.2fs %8d[%3d]f: Sil -> Sp detect; seg start: %7.2fs %8d\n",
                            (double) (r->tot_frm *
                                      r->spf) /
                            (double) (r->sps),
                            r->tot_frm, frm,
                            (double) (n * r->spf) / (double) (r->sps), n);
                }

                /* Now in SPEECH state; want to look for silence from end of this window */
                r->win_validfrm = 1;
                r->win_startfrm = frm;

                /* Count #sil frames remaining in reduced window (of 1 frame) */
                r->n_other = (r->frm_pow[frm] <= r->thresh_sil) ? 1 : 0;
            }
        }
    }
    else {
        if (r->n_other >= r->sil_onset) {
            /* End of speech detected; speech->sil transition */
            r->spseg_tail->nfrm += r->trailer;

            r->tail_state = CONT_AD_STATE_SIL;

            if (r->logfp) {
                int32 n;

                /* Where (in absolute time) this speech segment ends */
                n = r->spseg_tail->startfrm + r->spseg_tail->nfrm - 1;
                if (n >= CONT_AD_ADFRMSIZE)
                    n -= CONT_AD_ADFRMSIZE;
                n = frm - n;
                if (n < 0)
                    n += CONT_AD_ADFRMSIZE;
                n = r->tot_frm - n;

                fprintf(r->logfp,
                        "%7.2fs %8d[%3d]f: Sp -> Sil detect; seg end: %7.2fs %8d\n",
                        (double) (r->tot_frm * r->spf) /
                        (double) (r->sps), r->tot_frm, frm,
                        (double) (n * r->spf) / (double) (r->sps), n);
            }

            /* Now in SILENCE state; start looking for speech trailer+leader frames later */
            r->win_validfrm -= (r->trailer + r->leader - 1);
            r->win_startfrm += (r->trailer + r->leader - 1);
            if (r->win_startfrm >= CONT_AD_ADFRMSIZE)
                r->win_startfrm -= CONT_AD_ADFRMSIZE;

            /* Count #speech frames remaining in reduced window */
            r->n_other = 0;
            for (f = r->win_startfrm;;) {
                if (r->frm_pow[f] >= r->thresh_speech)
                    r->n_other++;

                if (f == frm)
                    break;

                f++;
                if (f >= CONT_AD_ADFRMSIZE)
                    f = 0;
            }
        }
        else {
            /* In speech state, and staying there; add this frame to segment */
            r->spseg_tail->nfrm++;
        }
    }

    /*
     * Get rid of oldest frame in analysis window.  Not quite correct;
     * thresholds could have changed over the window; should preserve
     * the original speech/silence label for the frame and undo it.  Later..
     */
    if (r->tail_state == CONT_AD_STATE_SIL) {
        if (r->frm_pow[r->win_startfrm] >= r->thresh_speech) {
            if (r->n_other > 0)
                r->n_other--;
        }
    }
    else {
        if (r->frm_pow[r->win_startfrm] <= r->thresh_sil) {
            if (r->n_other > 0)
                r->n_other--;
        }
    }
    r->win_validfrm--;
    r->win_startfrm++;
    if (r->win_startfrm >= CONT_AD_ADFRMSIZE)
        r->win_startfrm = 0;

    if (r->logfp)
        fflush(r->logfp);
}


static int32
max_siglvl(cont_ad_t * r, int32 startfrm, int32 nfrm)
{
    int32 siglvl, i, f;

    siglvl = 0;
    if (nfrm > 0) {
        for (i = 0, f = startfrm; i < nfrm; i++, f++) {
            if (f >= CONT_AD_ADFRMSIZE)
                f -= CONT_AD_ADFRMSIZE;
            if (r->frm_pow[f] > siglvl)
                siglvl = r->frm_pow[f];
        }
    }
    return siglvl;
}


#if 0
/*
 * RKM(2005/01/31): Where did this come from?  If needed, it should be called
 * cont_ad_get_audio_data.
 */
void
get_audio_data(cont_ad_t * r, int16 * buf, int32 max)
{
}
#endif


static void
cont_ad_read_log(cont_ad_t * r, int32 retval)
{
    spseg_t *seg;

    fprintf(r->logfp, "return from cont_ad_read() -> %d:\n", retval);
    fprintf(r->logfp, "\tstate: %d\n", r->state);
    fprintf(r->logfp, "\tread_ts: %d (%.2fs)\n",
            r->read_ts, (float32) r->read_ts / (float32) r->sps);
    fprintf(r->logfp, "\tseglen: %d (%.2fs)\n",
            r->seglen, (float32) r->seglen / (float32) r->sps);
    fprintf(r->logfp, "\tsiglvl: %d\n", r->siglvl);
    fprintf(r->logfp, "\theadfrm: %d\n", r->headfrm);
    fprintf(r->logfp, "\tn_frm: %d\n", r->n_frm);
    fprintf(r->logfp, "\tn_sample: %d\n", r->n_sample);
    fprintf(r->logfp, "\twin_startfrm: %d\n", r->win_startfrm);
    fprintf(r->logfp, "\twin_validfrm: %d\n", r->win_validfrm);
    fprintf(r->logfp, "\tnoise_level: %d\n", r->noise_level);
    fprintf(r->logfp, "\tthresh_sil: %d\n", r->thresh_sil);
    fprintf(r->logfp, "\tthresh_speech: %d\n", r->thresh_speech);
    fprintf(r->logfp, "\tn_other: %d\n", r->n_other);
    fprintf(r->logfp, "\ttail_state: %d\n", r->tail_state);
    fprintf(r->logfp, "\ttot_frm: %d\n", r->tot_frm);

    fprintf(r->logfp, "\tspseg:");
    for (seg = r->spseg_head; seg; seg = seg->next)
        fprintf(r->logfp, " %d[%d]", seg->startfrm, seg->nfrm);
    fprintf(r->logfp, "\n");

    fflush(r->logfp);
}


/*
 * Copy data from r->adbuf[sf], for nf frames, into buf.
 * All length checks must have been completed before this call; hence, this
 * function will copy exactly the specified number of frames.
 * 
 * Return value: Index of frame just after the segment copied, possibly wrapped
 * around to 0.
 */
static int32
buf_copy(cont_ad_t * r, int32 sf, int32 nf, int16 * buf)
{
    int32 f, l;

    assert((sf >= 0) && (sf < CONT_AD_ADFRMSIZE));
    assert(nf >= 0);

    if (sf + nf > CONT_AD_ADFRMSIZE) {
        /* Amount to be copied wraps around adbuf; copy in two stages */
        f = CONT_AD_ADFRMSIZE - sf;
        l = (f * r->spf);
        memcpy(buf, r->adbuf + (sf * r->spf), l * sizeof(int16));

        if (r->logfp) {
            fprintf(r->logfp,
                    "return %d speech frames [%d..%d]; %d samples\n",
                    f, sf, sf + f - 1, l);
        }

        buf += l;
        sf = 0;
        nf -= f;
    }

    if (nf > 0) {
        l = (nf * r->spf);
        memcpy(buf, r->adbuf + (sf * r->spf), l * sizeof(int16));

        if (r->logfp) {
            fprintf(r->logfp,
                    "return %d speech frames [%d..%d]; %d samples\n",
                    nf, sf, sf + nf - 1, l);
        }
    }

    if ((sf + nf) >= CONT_AD_ADFRMSIZE) {
        assert((sf + nf) == CONT_AD_ADFRMSIZE);
        return 0;
    }
    else
        return (sf + nf);
}


/*
 * Main function called by the application to filter out silence regions.
 * Maintains a linked list of speech segments pointing into r->adbuf and feeds
 * data to application from them.
 */
int32
cont_ad_read(cont_ad_t * r, int16 * buf, int32 max)
{
    int32 head, tail, tailfrm, flen, len, retval, newstate;
    int32 i, f, l;
    spseg_t *seg;
    int num_to_copy = 0, num_left = max;

    if ((r == NULL) || (buf == NULL))
        return -1;

    if (max < r->spf) {
        E_ERROR
            ("cont_ad_read requires buffer of at least %d samples\n",
             r->spf);
        return -1;
    }

    if (r->logfp) {
        fprintf(r->logfp, "cont_ad_read(,, %d)\n", max);
        fflush(r->logfp);
    }

    /*
     * First read as much of raw A/D as possible and available.  adbuf is not
     * really a circular buffer, so may have to read in two steps for wrapping
     * around.
     */
    head = r->headfrm * r->spf;
    tail = head + r->n_sample;
    len = r->n_sample - (r->n_frm * r->spf);    /* #partial frame samples at the tail */
    assert((len >= 0) && (len < r->spf));

    if ((tail < r->adbufsize) && (!r->eof)) {
        if (r->adfunc != NULL) {
            if ((l =
                 (*(r->adfunc)) (r->ad, r->adbuf + tail,
                                 r->adbufsize - tail)) < 0) {
                r->eof = 1;
                l = 0;
            }
        }
        else {
            /*
             * RKM(2005/02/01): Why would r->adfunc == NULL?  Where would this object
             * get its raw data from if r->adfunc == NULL?  Why is data getting copied
             * into r->adbuf from buf?  Where is this behavior documented?
             * If max >> num_to_copy, the 2nd memcpy below can have overlapping src and
             * dst regions, which isn't allowed by memcpy.
             * This block of code doesn't make sense.
             */
            num_to_copy = r->adbufsize - tail;
            num_left -= num_to_copy;
            if (num_to_copy > max) {
                num_to_copy = max;
                num_left = 0;
            }
            memcpy(r->adbuf + tail, buf, num_to_copy * sizeof(int16));
            memcpy(buf, buf + num_to_copy, num_left * sizeof(int16));
            l = num_to_copy;
        }

        if ((l > 0) && r->rawfp) {
            fwrite(r->adbuf + tail, sizeof(int16), l, r->rawfp);
            fflush(r->rawfp);
        }

        tail += l;
        len += l;
        r->n_sample += l;
    }
    if ((tail >= r->adbufsize) && (!r->eof)) {
        tail -= r->adbufsize;
        if (tail < head) {
            if (r->adfunc != NULL) {
                if ((l =
                     (*(r->adfunc)) (r->ad,
                                     r->adbuf + tail, head - tail)) < 0) {
                    r->eof = 1;
                    l = 0;
                }
            }
            else {
                /* RKM(2005/02/01): See comment above */
                num_to_copy = head - tail;
                if (num_to_copy > num_left)
                    num_to_copy = num_left;
                memcpy(r->adbuf + tail, buf, num_to_copy * sizeof(int16));
                l = num_to_copy;
            }

            if ((l > 0) && r->rawfp) {
                fwrite(r->adbuf + tail, sizeof(int16), l, r->rawfp);
                fflush(r->rawfp);
            }

            tail += l;
            len += l;
            r->n_sample += l;
        }
    }

    /* Compute frame power for unprocessed+new data and find speech/silence boundaries */
    tailfrm = (r->headfrm + r->n_frm);  /* Next free frame slot to be filled */
    if (tailfrm >= CONT_AD_ADFRMSIZE)
        tailfrm -= CONT_AD_ADFRMSIZE;
    for (; len >= r->spf; len -= r->spf) {
        compute_frame_pow(r, tailfrm);
        r->n_frm++;
        r->tot_frm++;

        /*
         * Find speech/sil state change, if any.  Also, if staying in speech state
         * add this frame to current speech segment.
         */
        boundary_detect(r, tailfrm);

        if (++tailfrm >= CONT_AD_ADFRMSIZE)
            tailfrm = 0;

        /* RKM: 2004-06-23: Moved this block from outside the enclosing loop */
        /* Update thresholds if time to do so */
        if (r->thresh_update <= 0) {
            find_thresh(r);
            decay_hist(r);
            r->thresh_update = CONT_AD_THRESH_UPDATE;

#if 1
            /*
             * Since threshold has been updated, recompute r->n_other.
             * (RKM: Is this really necessary?  Comment out??)
             */
            r->n_other = 0;
            if (r->tail_state == CONT_AD_STATE_SIL) {
                for (i = r->win_validfrm, f = r->win_startfrm; i > 0; --i) {
                    if (r->frm_pow[f] >= r->thresh_speech)
                        r->n_other++;

                    f++;
                    if (f >= CONT_AD_ADFRMSIZE)
                        f = 0;
                }
            }
            else {
                for (i = r->win_validfrm, f = r->win_startfrm; i > 0; --i) {
                    if (r->frm_pow[f] <= r->thresh_sil)
                        r->n_other++;

                    f++;
                    if (f >= CONT_AD_ADFRMSIZE)
                        f = 0;
                }
            }
#endif
        }
    }

    /*
     * If eof on input data source, cleanup the final segment.
     */
    if (r->eof) {
        if (r->tail_state == CONT_AD_STATE_SPEECH) {
            /*
             * Still inside a speech segment when input data got over.  Absort any
             * remaining frames into the final speech segment.
             */
            assert(r->spseg_tail != NULL);

            /* Absorb frames still in analysis window into final speech seg */
            assert((r->win_validfrm >= 0)
                   && (r->win_validfrm < r->winsize));
            r->spseg_tail->nfrm += r->win_validfrm;

            r->tail_state = CONT_AD_STATE_SIL;
        }

        r->win_startfrm += r->win_validfrm;
        if (r->win_startfrm >= CONT_AD_ADFRMSIZE)
            r->win_startfrm -= CONT_AD_ADFRMSIZE;
        r->win_validfrm = 0;
        r->n_other = 0;
    }

    /*
     * At last ready to copy speech data, if any, into caller's buffer.  Raw
     * speech data is segmented into alternating speech and silence segments.
     * But any single call to cont_ad_read will never cross a speech/silence
     * boundary.
     */
    seg = r->spseg_head;        /* first speech segment available, if any */

    if ((seg == NULL) || (r->headfrm != seg->startfrm)) {
        /*
         * Either no speech data available, or inside a silence segment.  Find
         * length of silence segment.
         */
        if (seg == NULL) {
            assert(r->tail_state == CONT_AD_STATE_SIL);

            flen =
                (r->eof) ? r->n_frm : r->n_frm - (r->winsize +
                                                  r->leader - 1);
            if (flen < 0)
                flen = 0;
        }
        else {
            flen = seg->startfrm - r->headfrm;
            if (flen < 0)
                flen += CONT_AD_ADFRMSIZE;
        }

        if (r->rawmode) {
            /* Restrict silence segment to user buffer size, integral #frames */
            f = max / r->spf;
            if (flen > f)
                flen = f;
        }

        newstate = CONT_AD_STATE_SIL;
    }
    else {
        flen = max / r->spf;    /* truncate read-size to integral #frames */
        if (flen > seg->nfrm)
            flen = seg->nfrm;   /* truncate further to this segment size */

        newstate = CONT_AD_STATE_SPEECH;
    }

    len = flen * r->spf;        /* #samples being consumed */

    r->siglvl = max_siglvl(r, r->headfrm, flen);

    if ((newstate == CONT_AD_STATE_SIL) && (!r->rawmode)) {
        /* Skip silence data */
        r->headfrm += flen;
        if (r->headfrm >= CONT_AD_ADFRMSIZE)
            r->headfrm -= CONT_AD_ADFRMSIZE;

        retval = 0;             /* #samples being copied/returned */
    }
    else {
        /* Copy speech/silence(in rawmode) data */
        r->headfrm = buf_copy(r, r->headfrm, flen, buf);

        retval = len;           /* #samples being copied/returned */
    }

    r->n_frm -= flen;
    r->n_sample -= len;
    assert((r->n_frm >= 0) && (r->n_sample >= 0));
    assert(r->win_validfrm <= r->n_frm);

    if (r->state == newstate)
        r->seglen += len;
    else
        r->seglen = len;
    r->state = newstate;

    if (newstate == CONT_AD_STATE_SPEECH) {
        seg->startfrm = r->headfrm;
        seg->nfrm -= flen;

        /* Free seg if empty and not recording into it */
        if ((seg->nfrm == 0)
            && (seg->next || (r->tail_state == CONT_AD_STATE_SIL))) {
            r->spseg_head = seg->next;
            if (seg->next == NULL)
                r->spseg_tail = NULL;
            free(seg);
        }
    }

    /* Update timestamp.  Total raw A/D read - those remaining to be consumed */
    r->read_ts = (r->tot_frm - r->n_frm) * r->spf;

    if (retval == 0)
        retval = (r->eof && (r->spseg_head == NULL)) ? -1 : 0;

    if (r->logfp)
        cont_ad_read_log(r, retval);

    return retval;
}


/*
 * Calibrate input channel for silence threshold.
 */
int32
cont_ad_calib(cont_ad_t * r)
{
    int32 i, f, s, k, len, tailfrm;

    if (r == NULL)
        return -1;

    /* clear histogram */
    for (i = 0; i < CONT_AD_POWHISTSIZE; i++)
        r->pow_hist[i] = 0;
    tailfrm = r->headfrm + r->n_frm;
    if (tailfrm >= CONT_AD_ADFRMSIZE)
        tailfrm -= CONT_AD_ADFRMSIZE;
    s = (tailfrm * r->spf);

    for (f = 0; f < (CONT_AD_POWHISTSIZE << 1); f++) {
        len = r->spf;
        while (len > 0) {
            /*Trouble */
            if ((k = (*(r->adfunc)) (r->ad, r->adbuf + s, len)) < 0)
                return -1;
            len -= k;
            s += k;
        }
        s -= r->spf;

        compute_frame_pow(r, tailfrm);
    }

    r->thresh_update = CONT_AD_THRESH_UPDATE;

    return (find_thresh(r));
}


int32
cont_ad_calib_loop(cont_ad_t * r, int16 * buf, int32 max)
{
    int32 i, s, len, tailfrm;
    static int32 finished = 1;
    static int32 f = 0;

    if (finished) {
        finished = 0;
        f = 0;

        /* clear histogram */
        for (i = 0; i < CONT_AD_POWHISTSIZE; i++)
            r->pow_hist[i] = 0;

    }

    tailfrm = r->headfrm + r->n_frm;
    if (tailfrm >= CONT_AD_ADFRMSIZE)
        tailfrm -= CONT_AD_ADFRMSIZE;
    s = (tailfrm * r->spf);

    len = r->spf;
    for (; f < (CONT_AD_POWHISTSIZE << 1); f++) {
        if (max < len)
            return 1;
        memcpy(r->adbuf + s, buf, len * sizeof(int16));
        max -= len;
        memcpy(buf, buf + len, max * sizeof(int16));

        compute_frame_pow(r, tailfrm);
    }

    finished = 1;
    return (find_thresh(r));
}


/* PWP 1/14/98 -- modified for compatibility with old code */
int32
cont_ad_set_thresh(cont_ad_t * r, int32 sil, int32 speech)
{
    if (r == NULL)
        return -1;

    if ((sil < 0) || (speech < 0)) {
        fprintf(stderr,
                "cont_ad_set_thresh: invalid threshold arguments: %d, %d\n",
                sil, speech);
        return -1;
    }
    r->delta_sil = (3 * sil) / 2;
    r->delta_speech = (3 * speech) / 2;

    return 0;
}


/*
 * PWP 1/14/98 -- set the changable params.
 *
 *   delta_sil, delta_speech, min_noise, and max_noise are in dB,
 *   winsize, speech_onset, sil_onset, leader and trailer are in frames of
 *   16 ms length (256 samples @ 16kHz sampling).
 */
int32
cont_ad_set_params(cont_ad_t * r, int32 delta_sil,
                   int32 delta_speech, int32 min_noise,
                   int32 max_noise, int32 winsize,
                   int32 speech_onset, int32 sil_onset, int32 leader,
                   int32 trailer, float32 adapt_rate)
{
    if ((delta_sil < 0) || (delta_speech < 0) || (min_noise < 0)
        || (max_noise < 0)) {
        E_ERROR("threshold arguments: "
                "%d, %d, %d, %d must all be >=0\n", delta_sil,
                delta_speech, min_noise, max_noise);
        return -1;
    }

    if ((speech_onset > winsize) || (speech_onset <= 0)
        || (winsize <= 0)) {
        E_ERROR
            ("speech_onset, %d, must be <= winsize, %d, and both >0\n",
             speech_onset, winsize);
        return -1;
    }

    if ((sil_onset > winsize) || (sil_onset <= 0) || (winsize <= 0)) {
        E_ERROR
            ("sil_onset, %d, must be <= winsize, %d, and both >0\n",
             sil_onset, winsize);
        return -1;
    }

    if (((leader + trailer) > winsize) || (leader <= 0)
        || (trailer <= 0)) {
        E_ERROR
            ("leader, %d, plus trailer, %d, must be <= winsize, %d, and both >0\n",
             leader, trailer, winsize);
        return -1;
    }

    if ((adapt_rate < 0.0) || (adapt_rate > 1.0)) {
        E_ERROR("adapt_rate, %e; must be in range 0..1\n", adapt_rate);
        return -1;
    }

    if (r == NULL)
        return -1;

    r->delta_sil = delta_sil;
    r->delta_speech = delta_speech;
    r->min_noise = min_noise;
    r->max_noise = max_noise;

    r->winsize = winsize;
    r->speech_onset = speech_onset;
    r->sil_onset = sil_onset;
    r->leader = leader;
    r->trailer = trailer;

    r->adapt_rate = adapt_rate;

    if (r->win_validfrm >= r->winsize)
        r->win_validfrm = r->winsize - 1;

    return 0;
}


/*
 * PWP 1/14/98 -- get the changable params.
 *
 *   delta_sil, delta_speech, min_noise, and max_noise are in dB,
 *   winsize, speech_onset, sil_onset, leader and trailer are in frames of
 *   16 ms length (256 samples @ 16kHz sampling).
 */
int32
cont_ad_get_params(cont_ad_t * r, int32 * delta_sil,
                   int32 * delta_speech, int32 * min_noise,
                   int32 * max_noise, int32 * winsize,
                   int32 * speech_onset, int32 * sil_onset,
                   int32 * leader, int32 * trailer, float32 * adapt_rate)
{
    if (!delta_sil || !delta_speech || !min_noise || !max_noise
        || !winsize || !speech_onset || !sil_onset || !leader
        || !trailer || !adapt_rate) {
        fprintf(stderr, "cont_ad_get_params: some param slots are NULL\n");
        return (-1);
    }

    if (r == NULL)
        return -1;

    *delta_sil = r->delta_sil;
    *delta_speech = r->delta_speech;
    *min_noise = r->min_noise;
    *max_noise = r->max_noise;

    *winsize = r->winsize;
    *speech_onset = r->speech_onset;
    *sil_onset = r->sil_onset;
    *leader = r->leader;
    *trailer = r->trailer;

    *adapt_rate = r->adapt_rate;

    return 0;
}


/*
 * Reset, discarded any accumulated speech.
 */
int32
cont_ad_reset(cont_ad_t * r)
{
    spseg_t *seg;

    if (r == NULL)
        return -1;

    while (r->spseg_head) {
        seg = r->spseg_head;
        r->spseg_head = seg->next;
        free(seg);
    }
    r->spseg_tail = NULL;

    r->headfrm = 0;
    r->n_frm = 0;
    r->n_sample = 0;
    r->win_startfrm = 0;
    r->win_validfrm = 0;
    r->n_other = 0;

    r->tail_state = CONT_AD_STATE_SIL;

    return 0;
}


int32
cont_ad_close(cont_ad_t * cont)
{
    if (cont == NULL)
        return -1;

    cont_ad_reset(cont);        /* Frees any remaining speech segments */

    free(cont->adbuf);
    free(cont->pow_hist);
    free(cont->frm_pow);
    free(cont);

    return 0;
}


int32
cont_ad_detach(cont_ad_t * c)
{
    if (c == NULL)
        return -1;

    c->ad = NULL;
    c->adfunc = NULL;
    return 0;
}


int32
cont_ad_attach(cont_ad_t * c, ad_rec_t * a,
               int32(*func) (ad_rec_t *, int16 *, int32))
{
    if (c == NULL)
        return -1;

    c->ad = a;
    c->adfunc = func;
    c->eof = 0;

    return 0;
}


int32
cont_set_thresh(cont_ad_t * r, int32 silence, int32 speech)
{
    int32 i, f;

    r->thresh_speech = speech;
    r->thresh_sil = silence;

    /* Since threshold has been updated, recompute r->n_other */
    r->n_other = 0;
    if (r->tail_state == CONT_AD_STATE_SIL) {
        for (i = r->win_validfrm, f = r->win_startfrm; i > 0; --i) {
            if (r->frm_pow[f] >= r->thresh_speech)
                r->n_other++;

            f++;
            if (f >= CONT_AD_ADFRMSIZE)
                f = 0;
        }
    }
    else if (r->tail_state == CONT_AD_STATE_SPEECH) {
        for (i = r->win_validfrm, f = r->win_startfrm; i > 0; --i) {
            if (r->frm_pow[f] <= r->thresh_sil)
                r->n_other++;

            f++;
            if (f >= CONT_AD_ADFRMSIZE)
                f = 0;
        }
    }

    return 0;
}


/*
 * Set the file pointer for dumping the raw input audio stream.
 */
int32
cont_ad_set_rawfp(cont_ad_t * r, FILE * fp)
{
    if (r == NULL)
        return -1;

    r->rawfp = fp;
    return 0;
}


/*
 * Set the file pointer for logging cont_ad progress.
 */
int32
cont_ad_set_logfp(cont_ad_t * r, FILE * fp)
{
    if (r == NULL)
        return -1;

    r->logfp = fp;
    return 0;
}


/*
 * One-time initialization.
 */
cont_ad_t *
cont_ad_init(ad_rec_t * a, int32(*func) (ad_rec_t *, int16 *, int32))
{
    cont_ad_t *r;

    if ((r = malloc(sizeof(*r))) == NULL) {
		E_ERROR_SYSTEM("allocation of cont_ad_t failed");
        return NULL;
    }

    r->ad = a;
    r->adfunc = func;
    r->eof = 0;
    r->rawmode = 0;

    if (a != NULL)
        r->sps = a->sps;
    else
        r->sps = CONT_AD_SPS;

    /* Set samples/frame such that when sps=16000, spf=256 */
    r->spf = (r->sps * 256) / CONT_AD_SPS;
    r->adbufsize = CONT_AD_ADFRMSIZE * r->spf;

    if ((r->adbuf = malloc(r->adbufsize * sizeof(*r->adbuf))) == NULL) {
        E_ERROR_SYSTEM("allocation of audio buffer failed");
        free(r);
        return NULL;
    }
    if ((r->pow_hist =
         calloc(CONT_AD_POWHISTSIZE, sizeof(*r->pow_hist))) == NULL) {
        E_ERROR_SYSTEM("allocation of power history buffer failed");
        free(r->adbuf);
        free(r);
        return NULL;
    }
    if ((r->frm_pow =
         calloc(CONT_AD_ADFRMSIZE, sizeof(*r->frm_pow))) == NULL) {
        E_ERROR_SYSTEM("allocation of frame power buffer failed");
        free(r->pow_hist);
        free(r->adbuf);
        free(r);
        return NULL;
    }

    r->state = CONT_AD_STATE_SIL;
    r->read_ts = 0;
    r->seglen = 0;
    r->siglvl = 0;
    r->prev_sample = 0;
    r->tot_frm = 0;
    r->noise_level = CONT_AD_DEFAULT_NOISE;

    r->auto_thresh = 1;
    r->delta_sil = CONT_AD_DELTA_SIL;
    r->delta_speech = CONT_AD_DELTA_SPEECH;
    r->min_noise = CONT_AD_MIN_NOISE;
    r->max_noise = CONT_AD_MAX_NOISE;
    r->winsize = CONT_AD_WINSIZE;
    r->speech_onset = CONT_AD_SPEECH_ONSET;
    r->sil_onset = CONT_AD_SIL_ONSET;
    r->leader = CONT_AD_LEADER;
    r->trailer = CONT_AD_TRAILER;

    r->thresh_sil = r->noise_level + r->delta_sil;
    r->thresh_speech = r->noise_level + r->delta_speech;
    r->thresh_update = CONT_AD_THRESH_UPDATE;
    r->adapt_rate = CONT_AD_ADAPT_RATE;

    r->tail_state = CONT_AD_STATE_SIL;

    r->spseg_head = NULL;
    r->spseg_tail = NULL;

    r->rawfp = NULL;
    r->logfp = NULL;

    cont_ad_reset(r);

    return r;
}


cont_ad_t *
cont_ad_init_rawmode(ad_rec_t * a,
                     int32(*func) (ad_rec_t *, int16 *, int32))
{
    cont_ad_t *r;

    r = cont_ad_init(a, func);
    r->rawmode = 1;

    return r;
}
