--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/vad.c	Wed Apr 03 05:31:37 2024 +0000
@@ -0,0 +1,1223 @@
+/***************************************************************************
+ *
+ *   File Name: vad.c
+ *
+ *   Purpose:   Contains all functions for voice activity detection, as
+ *              described in the high level specification of VAD.
+ *
+ *     Below is a listing of all the functions appearing in the file.
+ *     The functions are arranged according to their purpose.  Under
+ *     each heading, the ordering is hierarchical.
+ *
+ *     Resetting of static variables of VAD:
+ *       reset_vad()
+ *
+ *     Main routine of VAD (called by the speech encoder):
+ *       vad_computation()
+ *       Adaptive filtering and energy computation:
+ *         energy_computation()
+ *       Averaging of autocorrelation function values:
+ *         acf_averaging()
+ *       Computation of predictor values:
+ *         predictor_values()
+ *           schur_recursion()
+ *           step_up()
+ *           compute_rav1()
+ *       Spectral comparison:
+ *         spectral_comparison()
+ *       Information tone detection:
+ *         tone_detection()
+ *           step_up()
+ *       Threshold adaptation:
+ *         threshold_adaptation()
+ *       VAD decision:
+ *         vad_decision()
+ *       VAD hangover addition:
+ *         vad_hangover()
+ *
+ *     Periodicity detection routine (called by the speech encoder):
+ *       periodicity_detection()
+ *
+ **************************************************************************/
+
+#include "typedef.h"
+#include "cnst.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "count.h"
+#include "vad.h"
+
+/* Constants of VAD hangover addition */
+
+#define HANGCONST 10
+#define BURSTCONST 3
+
+/* Constant of spectral comparison */
+
+#define STAT_THRESH 3670L       /* 0.056 */
+
+/* Constants of periodicity detection */
+
+#define LTHRESH 2
+#define NTHRESH 4
+
+/* Pseudo floating point representations of constants
+   for threshold adaptation */
+
+#define M_PTH    32500          /*** 130000.0 ***/
+#define E_PTH    17
+#define M_PLEV   21667          /*** 346666.7 ***/
+#define E_PLEV   19
+#define M_MARGIN 16927          /*** 69333340 ***/
+#define E_MARGIN 27
+
+#define FAC 17203               /* 2.1 */
+
+/* Constants of tone detection */
+
+#define FREQTH 3189
+#define PREDTH 1464
+
+/* Static variables of VAD */
+
+static Word16 rvad[9], scal_rvad;
+static Pfloat thvad;
+static Word32 L_sacf[27];
+static Word32 L_sav0[36];
+static Word16 pt_sacf, pt_sav0;
+static Word32 L_lastdm;
+static Word16 adaptcount;
+static Word16 burstcount, hangcount;
+static Word16 oldlagcount, veryoldlagcount, oldlag;
+
+Word16 ptch;
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: vad_reset
+ *
+ *   PURPOSE:  Resets the static variables of the VAD to their
+ *             initial values
+ *
+ *************************************************************************/
+
+void vad_reset ()
+{
+    Word16 i;
+
+    /* Initialize rvad variables */
+    rvad[0] = 0x6000;
+    for (i = 1; i < 9; i++)
+    {
+        rvad[i] = 0;
+    }
+    scal_rvad = 7;
+
+    /* Initialize threshold level */
+    thvad.e = 20;               /*** exponent ***/
+    thvad.m = 27083;            /*** mantissa ***/
+
+    /* Initialize ACF averaging variables */
+    for (i = 0; i < 27; i++)
+    {
+        L_sacf[i] = 0L;
+    }
+    for (i = 0; i < 36; i++)
+    {
+        L_sav0[i] = 0L;
+    }
+    pt_sacf = 0;
+    pt_sav0 = 0;
+
+    /* Initialize spectral comparison variable */
+    L_lastdm = 0L;
+
+    /* Initialize threshold adaptation variable */
+    adaptcount = 0;
+
+    /* Initialize VAD hangover addition variables */
+    burstcount = 0;
+    hangcount = -1;
+
+    /* Initialize periodicity detection variables */
+    oldlagcount = 0;
+    veryoldlagcount = 0;
+    oldlag = 18;
+
+    ptch = 1;
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  vad_computation
+ *
+ *     PURPOSE:   Returns a decision as to whether the current frame being
+ *                processed by the speech encoder contains speech or not.
+ *
+ *     INPUTS:    r_h[0..8]     autocorrelation of input signal frame (msb)
+ *                r_l[0..8]     autocorrelation of input signal frame (lsb)
+ *                scal_acf      scaling factor for the autocorrelations
+ *                rc[0..3]      speech encoder reflection coefficients
+ *                ptch          flag to indicate a periodic signal component
+ *
+ *     OUTPUTS:   none
+ *
+ *     RETURN VALUE: vad decision
+ *
+ ***************************************************************************/
+
+Word16 vad_computation (
+    Word16 r_h[],
+    Word16 r_l[],
+    Word16 scal_acf,
+    Word16 rc[],
+    Word16 ptch
+)
+{
+    Word32 L_av0[9], L_av1[9];
+    Word16 vad, vvad, rav1[9], scal_rav1, stat, tone;
+    Pfloat acf0, pvad;
+
+    energy_computation (r_h, scal_acf, rvad, scal_rvad, &acf0, &pvad);
+    acf_averaging (r_h, r_l, scal_acf, L_av0, L_av1);
+    predictor_values (L_av1, rav1, &scal_rav1);
+    stat = spectral_comparison (rav1, scal_rav1, L_av0);        move16 (); 
+    tone_detection (rc, &tone);
+    threshold_adaptation (stat, ptch, tone, rav1, scal_rav1, pvad, acf0,
+                          rvad, &scal_rvad, &thvad);
+    vvad = vad_decision (pvad, thvad);                          move16 (); 
+    vad = vad_hangover (vvad);                                  move16 (); 
+
+    return vad;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  energy_computation
+ *
+ *     PURPOSE:   Computes the input and residual energies of the adaptive
+ *                filter in a floating point representation.
+ *
+ *     INPUTS:    r_h[0..8]      autocorrelation of input signal frame (msb)
+ *                scal_acf       scaling factor for the autocorrelations
+ *                rvad[0..8]     autocorrelated adaptive filter coefficients
+ *                scal_rvad      scaling factor for rvad[]
+ *
+ *     OUTPUTS:   *acf0          signal frame energy (mantissa+exponent)
+ *                *pvad          filtered signal energy (mantissa+exponent)
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void energy_computation (
+    Word16 r_h[],
+    Word16 scal_acf,
+    Word16 rvad[],
+    Word16 scal_rvad,
+    Pfloat * acf0,
+    Pfloat * pvad
+)
+{
+    Word16 i, temp, norm_prod;
+    Word32 L_temp;
+
+    /* r[0] is always greater than zero (no need to test for r[0] == 0) */
+
+    /* Computation of acf0 (exponent and mantissa) */
+
+    acf0->e = sub (32, scal_acf);       move16 (); 
+    acf0->m = r_h[0] & 0x7ff8;          move16 (); logic16 (); 
+
+    /* Computation of pvad (exponent and mantissa) */
+
+    pvad->e = add (acf0->e, 14);        move16 (); 
+    pvad->e = sub (pvad->e, scal_rvad); move16 (); 
+
+    L_temp = 0L;                        move32 (); 
+
+    for (i = 1; i <= 8; i++)
+    {
+        temp = shr (r_h[i], 3);
+        L_temp = L_mac (L_temp, temp, rvad[i]);
+    }
+
+    temp = shr (r_h[0], 3);
+    L_temp = L_add (L_temp, L_shr (L_mult (temp, rvad[0]), 1));
+
+    test (); 
+    if (L_temp <= 0L)
+    {
+        L_temp = 1L;                    move32 (); 
+    }
+    norm_prod = norm_l (L_temp);
+    pvad->e = sub (pvad->e, norm_prod); move16 (); 
+    pvad->m = extract_h (L_shl (L_temp, norm_prod));
+                                        move16 (); 
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  acf_averaging
+ *
+ *     PURPOSE:   Computes the arrays L_av0[0..8] and L_av1[0..8].
+ *
+ *     INPUTS:    r_h[0..8]     autocorrelation of input signal frame (msb)
+ *                r_l[0..8]     autocorrelation of input signal frame (lsb)
+ *                scal_acf      scaling factor for the autocorrelations
+ *
+ *     OUTPUTS:   L_av0[0..8]   ACF averaged over last four frames
+ *                L_av1[0..8]   ACF averaged over previous four frames
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void acf_averaging (
+    Word16 r_h[],
+    Word16 r_l[],
+    Word16 scal_acf,
+    Word32 L_av0[],
+    Word32 L_av1[]
+)
+{
+    Word32 L_temp;
+    Word16 scale;
+    Word16 i;
+
+    scale = add (9, scal_acf);
+
+    for (i = 0; i <= 8; i++)
+    {
+        L_temp = L_shr (L_Comp (r_h[i], r_l[i]), scale);
+        L_av0[i] = L_add (L_sacf[i], L_temp);           move32 (); 
+        L_av0[i] = L_add (L_sacf[i + 9], L_av0[i]);     move32 (); 
+        L_av0[i] = L_add (L_sacf[i + 18], L_av0[i]);    move32 (); 
+        L_sacf[pt_sacf + i] = L_temp;                   move32 (); 
+        L_av1[i] = L_sav0[pt_sav0 + i];                 move32 (); 
+        L_sav0[pt_sav0 + i] = L_av0[i];                 move32 (); 
+    }
+
+    /* Update the array pointers */
+
+    test (); 
+    if (sub (pt_sacf, 18) == 0)
+    {
+        pt_sacf = 0;                                    move16 (); 
+    }
+    else
+    {
+        pt_sacf = add (pt_sacf, 9);
+    }
+
+    test (); 
+    if (sub (pt_sav0, 27) == 0)
+    {
+        pt_sav0 = 0;                                    move16 (); 
+    }
+    else
+    {
+        pt_sav0 = add (pt_sav0, 9);
+    }
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  predictor_values
+ *
+ *     PURPOSE:   Computes the array rav[0..8] needed for the spectral
+ *                comparison and the threshold adaptation.
+ *
+ *     INPUTS:    L_av1[0..8]   ACF averaged over previous four frames
+ *
+ *     OUTPUTS:   rav1[0..8]    ACF obtained from L_av1
+ *                *scal_rav1    rav1[] scaling factor
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void predictor_values (
+    Word32 L_av1[],
+    Word16 rav1[],
+    Word16 *scal_rav1
+)
+{
+    Word16 vpar[8], aav1[9];
+
+    schur_recursion (L_av1, vpar);
+    step_up (8, vpar, aav1);
+    compute_rav1 (aav1, rav1, scal_rav1);
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  schur_recursion
+ *
+ *     PURPOSE:   Uses the Schur recursion to compute adaptive filter
+ *                reflection coefficients from an autorrelation function.
+ *
+ *     INPUTS:    L_av1[0..8]    autocorrelation function
+ *
+ *     OUTPUTS:   vpar[0..7]     reflection coefficients
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void schur_recursion (
+    Word32 L_av1[],
+    Word16 vpar[]
+)
+{
+    Word16 acf[9], pp[9], kk[9], temp;
+    Word16 i, k, m, n;
+
+    /*** Schur recursion with 16-bit arithmetic ***/
+
+    test (); move32 (); 
+    if (L_av1[0] == 0)
+    {
+        for (i = 0; i < 8; i++)
+        {
+            vpar[i] = 0;                                move16 (); 
+        }
+        return;
+    }
+    temp = norm_l (L_av1[0]);
+
+    for (k = 0; k <= 8; k++)
+    {
+        acf[k] = extract_h (L_shl (L_av1[k], temp));    move16 (); 
+    }
+
+    /*** Initialize arrays pp[..] and kk[..] for the recursion: ***/
+
+    for (i = 1; i <= 7; i++)
+    {
+        kk[9 - i] = acf[i];                             move16 (); 
+    }
+
+    for (i = 0; i <= 8; i++)
+    {
+        pp[i] = acf[i];                                 move16 (); 
+    }
+
+    /*** Compute Parcor coefficients: ***/
+
+    for (n = 0; n < 8; n++)
+    {
+        test (); 
+        if ((pp[0] == 0) ||
+            (sub (pp[0], abs_s (pp[1])) < 0))
+        {
+            for (i = n; i < 8; i++)
+            {
+                vpar[i] = 0;                            move16 (); 
+            }
+            return;
+        }
+        vpar[n] = div_s (abs_s (pp[1]), pp[0]);         move16 (); 
+
+        test ();                                        move16 (); 
+        if (pp[1] > 0)
+        {
+            vpar[n] = negate (vpar[n]);                 move16 (); 
+        }
+        test (); 
+        if (sub (n, 7) == 0)
+        {
+            return;
+        }
+        /*** Schur recursion: ***/
+
+        pp[0] = add (pp[0], mult_r (pp[1], vpar[n]));   move16 (); 
+
+        for (m = 1; m <= 7 - n; m++)
+        {
+            pp[m] = add (pp[1 + m], mult_r (kk[9 - m], vpar[n]));
+                                                        move16 (); 
+            kk[9 - m] = add (kk[9 - m], mult_r (pp[1 + m], vpar[n]));
+                                                        move16 (); 
+        }
+    }
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  step_up
+ *
+ *     PURPOSE:   Computes the transversal filter coefficients from the
+ *                reflection coefficients.
+ *
+ *     INPUTS:    np               filter order (2..8)
+ *                vpar[0..np-1]    reflection coefficients
+ *
+ *     OUTPUTS:   aav1[0..np]      transversal filter coefficients
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void step_up (
+    Word16 np,
+    Word16 vpar[],
+    Word16 aav1[]
+)
+{
+    Word32 L_coef[9], L_work[9];
+    Word16 temp;
+    Word16 i, m;
+
+    /*** Initialization of the step-up recursion ***/
+
+    L_coef[0] = 0x20000000L;    move32 (); 
+    L_coef[1] = L_shl (L_deposit_l (vpar[0]), 14);              move32 (); 
+
+    /*** Loop on the LPC analysis order: ***/
+
+    for (m = 2; m <= np; m++)
+    {
+        for (i = 1; i < m; i++)
+        {
+            temp = extract_h (L_coef[m - i]);
+            L_work[i] = L_mac (L_coef[i], vpar[m - 1], temp);   move32 (); 
+        }
+
+        for (i = 1; i < m; i++)
+        {
+            L_coef[i] = L_work[i];                              move32 (); 
+        }
+
+        L_coef[m] = L_shl (L_deposit_l (vpar[m - 1]), 14);      move32 (); 
+    }
+
+    /*** Keep the aav1[0..np] in 15 bits ***/
+
+    for (i = 0; i <= np; i++)
+    {
+        aav1[i] = extract_h (L_shr (L_coef[i], 3));             move32 (); 
+    }
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  compute_rav1
+ *
+ *     PURPOSE:   Computes the autocorrelation function of the adaptive
+ *                filter coefficients.
+ *
+ *     INPUTS:    aav1[0..8]     adaptive filter coefficients
+ *
+ *     OUTPUTS:   rav1[0..8]     ACF of aav1
+ *                *scal_rav1     rav1[] scaling factor
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void compute_rav1 (
+    Word16 aav1[],
+    Word16 rav1[],
+    Word16 *scal_rav1
+)
+{
+    Word32 L_work[9];
+    Word16 i, k;
+
+    /*** Computation of the rav1[0..8] ***/
+
+    for (i = 0; i <= 8; i++)
+    {
+        L_work[i] = 0L;                                           move32 (); 
+
+        for (k = 0; k <= 8 - i; k++)
+        {
+            L_work[i] = L_mac (L_work[i], aav1[k], aav1[k + i]);  move32 (); 
+        }
+    }
+
+    test (); move32 (); 
+    if (L_work[0] == 0L)
+    {
+        *scal_rav1 = 0;                                           move16 (); 
+    }
+    else
+    {
+        *scal_rav1 = norm_l (L_work[0]);
+    }
+
+    for (i = 0; i <= 8; i++)
+    {
+        rav1[i] = extract_h (L_shl (L_work[i], *scal_rav1));      move16 (); 
+    }
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  spectral_comparison
+ *
+ *     PURPOSE:   Computes the stat flag needed for the threshold
+ *                adaptation decision.
+ *
+ *     INPUTS:    rav1[0..8]      ACF obtained from L_av1
+ *                *scal_rav1      rav1[] scaling factor
+ *                L_av0[0..8]     ACF averaged over last four frames
+ *
+ *     OUTPUTS:   none
+ *
+ *     RETURN VALUE: flag to indicate spectral stationarity
+ *
+ ***************************************************************************/
+
+Word16 spectral_comparison (
+    Word16 rav1[],
+    Word16 scal_rav1,
+    Word32 L_av0[]
+)
+{
+    Word32 L_dm, L_sump, L_temp;
+    Word16 stat, sav0[9], shift, divshift, temp;
+    Word16 i;
+
+    /*** Re-normalize L_av0[0..8] ***/
+
+    test (); move32 (); 
+    if (L_av0[0] == 0L)
+    {
+        for (i = 0; i <= 8; i++)
+        {
+            sav0[i] = 0x0fff;   /* 4095 */                      move16 (); 
+        }
+    }
+    else
+    {
+        shift = sub (norm_l (L_av0[0]), 3);
+        for (i = 0; i <= 8; i++)
+        {
+            sav0[i] = extract_h (L_shl (L_av0[i], shift));      move16 (); 
+        }
+    }
+
+    /*** Compute partial sum of dm ***/
+
+    L_sump = 0L;                                                move32 (); 
+    for (i = 1; i <= 8; i++)
+    {
+        L_sump = L_mac (L_sump, rav1[i], sav0[i]);
+    }
+
+    /*** Compute the division of the partial sum by sav0[0] ***/
+
+    test (); 
+    if (L_sump < 0L)
+    {
+        L_temp = L_negate (L_sump);
+    }
+    else
+    {
+        L_temp = L_sump;                                        move32 (); 
+    }
+
+    test (); 
+    if (L_temp == 0L)
+    {
+        L_dm = 0L;                                              move32 (); 
+        shift = 0;                                              move16 (); 
+    }
+    else
+    {
+        sav0[0] = shl (sav0[0], 3);                             move16 (); 
+        shift = norm_l (L_temp);
+        temp = extract_h (L_shl (L_temp, shift));
+
+        test (); 
+        if (sub (sav0[0], temp) >= 0)
+        {
+            divshift = 0;                                       move16 (); 
+            temp = div_s (temp, sav0[0]);
+        }
+        else
+        {
+            divshift = 1;                                       move16 (); 
+            temp = sub (temp, sav0[0]);
+            temp = div_s (temp, sav0[0]);
+        }
+
+        test (); 
+        if (sub (divshift, 1) == 0)
+        {
+            L_dm = 0x8000L;                                     move32 (); 
+        }
+        else
+        {
+            L_dm = 0L;                                          move32 (); 
+        }
+
+        L_dm = L_shl (L_add (L_dm, L_deposit_l (temp)), 1);
+
+        test (); 
+        if (L_sump < 0L)
+        {
+            L_dm = L_negate (L_dm);
+        }
+    }
+
+    /*** Re-normalization and final computation of L_dm ***/
+
+    L_dm = L_shl (L_dm, 14);
+    L_dm = L_shr (L_dm, shift);
+    L_dm = L_add (L_dm, L_shl (L_deposit_l (rav1[0]), 11));
+    L_dm = L_shr (L_dm, scal_rav1);
+
+    /*** Compute the difference and save L_dm ***/
+
+    L_temp = L_sub (L_dm, L_lastdm);
+    L_lastdm = L_dm;                                            move32 (); 
+
+    test (); 
+    if (L_temp < 0L)
+    {
+        L_temp = L_negate (L_temp);
+    }
+    /*** Evaluation of the stat flag ***/
+
+    L_temp = L_sub (L_temp, STAT_THRESH);
+
+    test (); 
+    if (L_temp < 0L)
+    {
+        stat = 1;                                               move16 (); 
+    }
+    else
+    {
+        stat = 0;                                               move16 (); 
+    }
+
+    return stat;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  threshold_adaptation
+ *
+ *     PURPOSE:   Evaluates the secondary VAD decision.  If speech is not
+ *                present then the noise model rvad and adaptive threshold
+ *                thvad are updated.
+ *
+ *     INPUTS:    stat          flag to indicate spectral stationarity
+ *                ptch          flag to indicate a periodic signal component
+ *                tone          flag to indicate a tone signal component
+ *                rav1[0..8]    ACF obtained from L_av1
+ *                scal_rav1     rav1[] scaling factor
+ *                pvad          filtered signal energy (mantissa+exponent)
+ *                acf0          signal frame energy (mantissa+exponent)
+ *
+ *     OUTPUTS:   rvad[0..8]    autocorrelated adaptive filter coefficients
+ *                *scal_rvad    rvad[] scaling factor
+ *                *thvad        decision threshold (mantissa+exponent)
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void threshold_adaptation (
+    Word16 stat,
+    Word16 ptch,
+    Word16 tone,
+    Word16 rav1[],
+    Word16 scal_rav1,
+    Pfloat pvad,
+    Pfloat acf0,
+    Word16 rvad[],
+    Word16 *scal_rvad,
+    Pfloat * thvad
+)
+{
+    Word16 comp, comp2;
+    Word32 L_temp;
+    Word16 temp;
+    Pfloat p_temp;
+    Word16 i;
+
+    comp = 0;                                           move16 (); 
+
+    /*** Test if acf0 < pth; if yes set thvad to plev ***/
+
+    test (); 
+    if (sub (acf0.e, E_PTH) < 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); test (); 
+    if ((sub (acf0.e, E_PTH) == 0) && (sub (acf0.m, M_PTH) < 0))
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); 
+    if (sub (comp, 1) == 0)
+    {
+        thvad->e = E_PLEV;                              move16 (); 
+        thvad->m = M_PLEV;                              move16 (); 
+
+        return;
+    }
+    /*** Test if an adaption is required ***/
+
+    test (); 
+    if (sub (ptch, 1) == 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); 
+    if (stat == 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); 
+    if (sub (tone, 1) == 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); 
+    if (sub (comp, 1) == 0)
+    {
+        adaptcount = 0;                                 move16 (); 
+        return;
+    }
+    /*** Increment adaptcount ***/
+
+    adaptcount = add (adaptcount, 1);
+    test (); 
+    if (sub (adaptcount, 8) <= 0)
+    {
+        return;
+    }
+    /*** computation of thvad-(thvad/dec) ***/
+
+    thvad->m = sub (thvad->m, shr (thvad->m, 5));       move16 (); 
+
+    test (); 
+    if (sub (thvad->m, 0x4000) < 0)
+    {
+        thvad->m = shl (thvad->m, 1);                   move16 (); 
+        thvad->e = sub (thvad->e, 1);                   move16 (); 
+    }
+    /*** computation of pvad*fac ***/
+
+    L_temp = L_mult (pvad.m, FAC);
+    L_temp = L_shr (L_temp, 15);
+    p_temp.e = add (pvad.e, 1);                         move16 (); 
+
+    test (); 
+    if (L_temp > 0x7fffL)
+    {
+        L_temp = L_shr (L_temp, 1);
+        p_temp.e = add (p_temp.e, 1);                   move16 (); 
+    }
+    p_temp.m = extract_l (L_temp);                      move16 (); 
+
+    /*** test if thvad < pvad*fac ***/
+
+    test (); 
+    if (sub (thvad->e, p_temp.e) < 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); test (); 
+    if ((sub (thvad->e, p_temp.e) == 0) &&
+        (sub (thvad->m, p_temp.m) < 0))
+    {
+        comp = 1;                                       move16 (); 
+    }
+    /*** compute minimum(thvad+(thvad/inc), pvad*fac) when comp = 1 ***/
+
+    test (); 
+    if (sub (comp, 1) == 0)
+    {
+        /*** compute thvad + (thvad/inc) ***/
+
+        L_temp = L_add (L_deposit_l (thvad->m),
+                        L_deposit_l (shr (thvad->m, 4)));
+
+        test (); 
+        if (L_sub (L_temp, 0x7fffL) > 0)
+        {
+            thvad->m = extract_l (L_shr (L_temp, 1));   move16 (); 
+            thvad->e = add (thvad->e, 1);               move16 (); 
+        }
+        else
+        {
+            thvad->m = extract_l (L_temp);              move16 (); 
+        }
+
+        comp2 = 0;                                      move16 (); 
+
+        test (); 
+        if (sub (p_temp.e, thvad->e) < 0)
+        {
+            comp2 = 1;                                  move16 (); 
+        }
+        test (); test (); 
+        if ((sub (p_temp.e, thvad->e) == 0) &&
+            (sub (p_temp.m, thvad->m) < 0))
+        {
+            comp2 = 1;                                  move16 (); 
+        }
+        test (); 
+        if (sub (comp2, 1) == 0)
+        {
+            thvad->e = p_temp.e;move16 (); 
+            thvad->m = p_temp.m;move16 (); 
+        }
+    }
+    /*** compute pvad + margin ***/
+
+    test (); 
+    if (sub (pvad.e, E_MARGIN) == 0)
+    {
+        L_temp = L_add (L_deposit_l (pvad.m), L_deposit_l (M_MARGIN));
+        p_temp.m = extract_l (L_shr (L_temp, 1));       move16 (); 
+        p_temp.e = add (pvad.e, 1);     move16 (); 
+    }
+    else
+    {
+        test (); 
+        if (sub (pvad.e, E_MARGIN) > 0)
+        {
+            temp = sub (pvad.e, E_MARGIN);
+            temp = shr (M_MARGIN, temp);
+            L_temp = L_add (L_deposit_l (pvad.m), L_deposit_l (temp));
+
+            test (); 
+            if (L_sub (L_temp, 0x7fffL) > 0)
+            {
+                p_temp.e = add (pvad.e, 1);             move16 (); 
+                p_temp.m = extract_l (L_shr (L_temp, 1));
+                                                        move16 (); 
+            }
+            else
+            {
+                p_temp.e = pvad.e;                      move16 (); 
+                p_temp.m = extract_l (L_temp);          move16 (); 
+            }
+        }
+        else
+        {
+            temp = sub (E_MARGIN, pvad.e);
+            temp = shr (pvad.m, temp);
+            L_temp = L_add (L_deposit_l (M_MARGIN), L_deposit_l (temp));
+
+            test (); 
+            if (L_sub (L_temp, 0x7fffL) > 0)
+            {
+                p_temp.e = add (E_MARGIN, 1);           move16 (); 
+                p_temp.m = extract_l (L_shr (L_temp, 1));
+                                                        move16 (); 
+            }
+            else
+            {
+                p_temp.e = E_MARGIN;                    move16 (); 
+                p_temp.m = extract_l (L_temp);          move16 (); 
+            }
+        }
+    }
+
+    /*** Test if thvad > pvad + margin ***/
+
+    comp = 0;                                           move16 (); 
+
+    test (); 
+    if (sub (thvad->e, p_temp.e) > 0)
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); test (); 
+    if ((sub (thvad->e, p_temp.e) == 0) &&
+        (sub (thvad->m, p_temp.m) > 0))
+    {
+        comp = 1;                                       move16 (); 
+    }
+    test (); 
+    if (sub (comp, 1) == 0)
+    {
+        thvad->e = p_temp.e;                            move16 (); 
+        thvad->m = p_temp.m;                            move16 (); 
+    }
+    /*** Normalise and retain rvad[0..8] in memory ***/
+
+    *scal_rvad = scal_rav1;                             move16 (); 
+
+    for (i = 0; i <= 8; i++)
+    {
+        rvad[i] = rav1[i];                              move16 (); 
+    }
+
+    /*** Set adaptcount to adp + 1 ***/
+
+    adaptcount = 9;                                     move16 (); 
+
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  tone_detection
+ *
+ *     PURPOSE:   Computes the tone flag needed for the threshold
+ *                adaptation decision.
+ *
+ *     INPUTS:    rc[0..3]    reflection coefficients calculated in the
+ *                            speech encoder short term predictor
+ *
+ *     OUTPUTS:   *tone       flag to indicate a periodic signal component
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void tone_detection (
+    Word16 rc[],
+    Word16 *tone
+)
+{
+    Word32 L_num, L_den, L_temp;
+    Word16 temp, prederr, a[3];
+    Word16 i;
+
+    *tone = 0;                  move16 (); 
+
+    /*** Calculate filter coefficients ***/
+
+    step_up (2, rc, a);
+
+    /*** Calculate ( a[1] * a[1] ) ***/
+
+    temp = shl (a[1], 3);
+    L_den = L_mult (temp, temp);
+
+    /*** Calculate ( 4*a[2] - a[1]*a[1] ) ***/
+
+    L_temp = L_shl (L_deposit_h (a[2]), 3);
+    L_num = L_sub (L_temp, L_den);
+
+    /*** Check if pole frequency is less than 385 Hz ***/
+
+    test (); 
+    if (L_num <= 0)
+    {
+        return;
+    }
+    test (); move16 (); 
+    if (a[1] < 0)
+    {
+        temp = extract_h (L_den);
+        L_den = L_mult (temp, FREQTH);
+
+        L_temp = L_sub (L_num, L_den);
+
+        test (); 
+        if (L_temp < 0)
+        {
+            return;
+        }
+    }
+    /*** Calculate normalised prediction error ***/
+
+    prederr = 0x7fff;           move16 (); 
+
+    for (i = 0; i < 4; i++)
+    {
+        temp = mult (rc[i], rc[i]);
+        temp = sub (0x7fff, temp);
+        prederr = mult (prederr, temp);
+    }
+
+    /*** Test if prediction error is smaller than threshold ***/
+
+    temp = sub (prederr, PREDTH);
+
+    test (); 
+    if (temp < 0)
+    {
+        *tone = 1;              move16 (); 
+    }
+    return;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  vad_decision
+ *
+ *     PURPOSE:   Computes the VAD decision based on the comparison of the
+ *                floating point representations of pvad and thvad.
+ *
+ *     INPUTS:    pvad          filtered signal energy (mantissa+exponent)
+ *                thvad         decision threshold (mantissa+exponent)
+ *
+ *     OUTPUTS:   none
+ *
+ *     RETURN VALUE: vad decision before hangover is added
+ *
+ ***************************************************************************/
+
+Word16 vad_decision (
+    Pfloat pvad,
+    Pfloat thvad
+)
+{
+    Word16 vvad;
+
+    test (); test (); test (); 
+    if (sub (pvad.e, thvad.e) > 0)
+    {
+        vvad = 1;               move16 (); 
+    }
+    else if ((sub (pvad.e, thvad.e) == 0) &&
+               (sub (pvad.m, thvad.m) > 0))
+    {
+        vvad = 1;               move16 (); 
+    }
+    else
+    {
+        vvad = 0;               move16 (); 
+    }
+
+    return vvad;
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  vad_hangover
+ *
+ *     PURPOSE:   Computes the final VAD decision for the current frame
+ *                being processed.
+ *
+ *     INPUTS:    vvad           vad decision before hangover is added
+ *
+ *     OUTPUTS:   none
+ *
+ *     RETURN VALUE: vad decision after hangover is added
+ *
+ ***************************************************************************/
+
+Word16 vad_hangover (
+    Word16 vvad
+)
+{
+    test (); 
+    if (sub (vvad, 1) == 0)
+    {
+        burstcount = add (burstcount, 1);
+    }
+    else
+    {
+        burstcount = 0;         move16 (); 
+    }
+
+    test (); 
+    if (sub (burstcount, BURSTCONST) >= 0)
+    {
+        hangcount = HANGCONST;  move16 (); 
+        burstcount = BURSTCONST;move16 (); 
+    }
+    test (); 
+    if (hangcount >= 0)
+    {
+        hangcount = sub (hangcount, 1);
+        return 1;               /* vad = 1 */
+    }
+    return vvad;                /* vad = vvad */
+}
+
+/****************************************************************************
+ *
+ *     FUNCTION:  periodicity_update
+ *
+ *     PURPOSE:   Computes the ptch flag needed for the threshold
+ *                adaptation decision for the next frame.
+ *
+ *     INPUTS:    lags[0..1]       speech encoder long term predictor lags
+ *
+ *     OUTPUTS:   *ptch            Boolean voiced / unvoiced decision
+ *
+ *     RETURN VALUE: none
+ *
+ ***************************************************************************/
+
+void periodicity_update (
+    Word16 lags[],
+    Word16 *ptch
+)
+{
+    Word16 minlag, maxlag, lagcount, temp;
+    Word16 i;
+
+    /*** Run loop for the two halves in the frame ***/
+
+    lagcount = 0;               move16 (); 
+
+    for (i = 0; i <= 1; i++)
+    {
+        /*** Search the maximum and minimum of consecutive lags ***/
+
+        test (); 
+        if (sub (oldlag, lags[i]) > 0)
+        {
+            minlag = lags[i];   move16 (); 
+            maxlag = oldlag;    move16 (); 
+        }
+        else
+        {
+            minlag = oldlag;    move16 (); 
+            maxlag = lags[i];   move16 (); 
+        }
+
+        temp = sub (maxlag, minlag);
+
+        test (); 
+        if (sub (temp, LTHRESH) < 0)
+        {
+            lagcount = add (lagcount, 1);
+        }
+        /*** Save the current LTP lag ***/
+
+        oldlag = lags[i];       move16 (); 
+    }
+
+    /*** Update the veryoldlagcount and oldlagcount ***/
+
+    veryoldlagcount = oldlagcount;
+                                move16 (); 
+    oldlagcount = lagcount;     move16 (); 
+
+    /*** Make ptch decision ready for next frame ***/
+
+    temp = add (oldlagcount, veryoldlagcount);
+
+    test (); 
+    if (sub (temp, NTHRESH) >= 0)
+    {
+        *ptch = 1;              move16 (); 
+    }
+    else
+    {
+        *ptch = 0;              move16 (); 
+    }
+
+    return;
+}