--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgsmefr/dtx_enc.c	Sat Dec 10 02:25:20 2022 +0000
@@ -0,0 +1,442 @@
+/*
+ * This file is a product of splitting ETSI EFR dtx.c into parts;
+ * the present module is the encoder-specific part.
+ */
+
+#include "gsm_efr.h"
+#include "typedef.h"
+#include "namespace.h"
+#include "basic_op.h"
+#include "cnst.h"
+#include "sig_proc.h"
+#include "memops.h"
+#include "no_count.h"
+#include "dtx.h"
+#include "dtx_defs.h"
+#include "enc_state.h"
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: reset_tx_dtx
+ *
+ *   PURPOSE:  Resets the static variables of the TX DTX handler to their
+ *             initial values
+ *
+ *************************************************************************/
+
+void reset_tx_dtx (struct EFR_encoder_state *st)
+{
+    Word16 i;
+
+    /* suppose infinitely long speech period before start */
+
+    st->txdtx_hangover = DTX_HANGOVER;
+    st->txdtx_N_elapsed = 0x7fff;
+    st->txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG;
+
+    for (i = 0; i < 6; i++)
+    {
+        st->old_CN_mem_tx[i] = 0;
+    }
+
+    for (i = 0; i < DTX_HANGOVER; i++)
+    {
+        st->lsf_old_tx[i][0] = 1384;
+        st->lsf_old_tx[i][1] = 2077;
+        st->lsf_old_tx[i][2] = 3420;
+        st->lsf_old_tx[i][3] = 5108;
+        st->lsf_old_tx[i][4] = 6742;
+        st->lsf_old_tx[i][5] = 8122;
+        st->lsf_old_tx[i][6] = 9863;
+        st->lsf_old_tx[i][7] = 11092;
+        st->lsf_old_tx[i][8] = 12714;
+        st->lsf_old_tx[i][9] = 13701;
+    }
+
+    for (i = 0; i < 4 * DTX_HANGOVER; i++)
+    {
+        st->gain_code_old_tx[i] = 0;
+    }
+
+    st->L_pn_seed_tx = PN_INITIAL_SEED;
+
+    st->buf_p_tx = 0;
+    return;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: tx_dtx
+ *
+ *   PURPOSE: DTX handler of the speech encoder. Determines when to add
+ *            the hangover period to the end of the speech burst, and
+ *            also determines when to use old SID parameters, and when
+ *            to update the SID parameters. This function also initializes
+ *            the pseudo noise generator shift register.
+ *
+ *            Operation of the TX DTX handler is based on the VAD flag
+ *            given as input from the speech encoder.
+ *
+ *   INPUTS:      VAD_flag      Voice activity decision
+ *                *txdtx_ctrl   Old encoder DTX control word
+ *
+ *   OUTPUTS:     *txdtx_ctrl   Updated encoder DTX control word
+ *                L_pn_seed_tx  Initialized pseudo noise generator shift
+ *                              register (global variable)
+ *
+ *   RETURN VALUE: none
+ *
+ *************************************************************************/
+
+void tx_dtx (
+    struct EFR_encoder_state *st,
+    Word16 VAD_flag
+)
+{
+    /* N_elapsed (frames since last SID update) is incremented. If SID
+       is updated N_elapsed is cleared later in this function */
+
+    st->txdtx_N_elapsed = add (st->txdtx_N_elapsed, 1);
+
+    /* If voice activity was detected, reset hangover counter */
+
+    if (sub (VAD_flag, 1) == 0)
+    {
+        st->txdtx_hangover = DTX_HANGOVER;
+        st->txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG;
+    }
+    else
+    {
+        if (st->txdtx_hangover == 0)
+        {
+            /* Hangover period is over, SID should be updated */
+
+            st->txdtx_N_elapsed = 0;
+
+            /* Check if this is the first frame after hangover period */
+            if ((st->txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0)
+            {
+                st->txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE
+                    | TX_SID_UPDATE;
+                st->L_pn_seed_tx = PN_INITIAL_SEED;
+            }
+            else
+            {
+                st->txdtx_ctrl = TX_SID_UPDATE;
+            }
+        }
+        else
+        {
+            /* Hangover period is not over, update hangover counter */
+            st->txdtx_hangover = sub (st->txdtx_hangover, 1);
+
+            /* Check if elapsed time from last SID update is greater than
+               threshold. If not, set SP=0 (although hangover period is not
+               over) and use old SID parameters for new SID frame.
+               N_elapsed counter must be summed with hangover counter in order
+               to avoid erroneus SP=1 decision in case when N_elapsed is grown
+               bigger than threshold and hangover period is still active */
+
+            if (sub (add (st->txdtx_N_elapsed, st->txdtx_hangover),
+                     DTX_ELAPSED_THRESHOLD) < 0)
+            {
+                /* old SID frame should be used */
+                st->txdtx_ctrl = TX_USE_OLD_SID;
+            }
+            else
+            {
+                if ((st->txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0)
+                {
+                    st->txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE
+                        | TX_HANGOVER_ACTIVE
+                        | TX_SP_FLAG;
+                }
+                else
+                {
+                    st->txdtx_ctrl = TX_HANGOVER_ACTIVE
+                        | TX_SP_FLAG;
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: CN_encoding
+ *
+ *   PURPOSE:  Encoding of the comfort noise parameters into a SID frame.
+ *             Use old SID parameters if necessary. Set the parameter
+ *             indices not used by comfort noise parameters to zero.
+ *
+ *   INPUTS:      params[0..56]  Comfort noise parameter frame from the
+ *                               speech encoder
+ *                txdtx_ctrl     TX DTX handler control word
+ *
+ *   OUTPUTS:     params[0..56]  Comfort noise encoded parameter frame
+ *
+ *   RETURN VALUE: none
+ *
+ *************************************************************************/
+
+void CN_encoding (
+    struct EFR_encoder_state *st,
+    Word16 params[],
+    Word16 txdtx_ctrl
+)
+{
+    Word16 i;
+
+    if ((txdtx_ctrl & TX_SID_UPDATE) != 0)
+    {
+        /* Store new CN parameters in memory to be used later as old
+           CN parameters */
+
+        /* LPC parameter indices */
+        for (i = 0; i < 5; i++)
+        {
+            st->old_CN_mem_tx[i] = params[i];
+        }
+        /* Codebook index computed in last subframe */
+        st->old_CN_mem_tx[5] = params[56];
+    }
+    if ((txdtx_ctrl & TX_USE_OLD_SID) != 0)
+    {
+        /* Use old CN parameters previously stored in memory */
+        for (i = 0; i < 5; i++)
+        {
+            params[i] = st->old_CN_mem_tx[i];
+        }
+        params[17] = st->old_CN_mem_tx[5];
+        params[30] = st->old_CN_mem_tx[5];
+        params[43] = st->old_CN_mem_tx[5];
+        params[56] = st->old_CN_mem_tx[5];
+    }
+    /* Set all the rest of the parameters to zero (SID codeword will
+       be written later) */
+    for (i = 0; i < 12; i++)
+    {
+        params[i + 5] = 0;
+        params[i + 18] = 0;
+        params[i + 31] = 0;
+        params[i + 44] = 0;
+    }
+
+    return;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: aver_lsf_history
+ *
+ *   PURPOSE: Compute the averaged LSF parameter vector. Computation is
+ *            performed by averaging the LSF parameter vectors which exist
+ *            in the LSF parameter history, together with the LSF
+ *            parameter vectors of the current frame.
+ *
+ *   INPUTS:      lsf_old[0..DTX_HANGOVER-1][0..M-1]
+ *                                   LSF parameter history
+ *                lsf1[0..M-1]       LSF vector of the 1st half of the frame
+ *                lsf2[0..M-1]       LSF vector of the 2nd half of the frame
+ *
+ *   OUTPUTS:     lsf_aver[0..M-1]   Averaged LSF parameter vector
+ *
+ *   RETURN VALUE: none
+ *
+ *************************************************************************/
+
+void aver_lsf_history (
+    Word16 lsf_old[DTX_HANGOVER][M],
+    Word16 lsf1[M],
+    Word16 lsf2[M],
+    Word16 lsf_aver[M]
+)
+{
+    Word16 i, j;
+    Word32 L_temp;
+
+    for (j = 0; j < M; j++)
+    {
+        L_temp = L_mult (0x3fff, lsf1[j]);
+        L_temp = L_mac (L_temp, 0x3fff, lsf2[j]);
+        L_temp = L_mult (INV_DTX_HANGOVER_P1, extract_h (L_temp));
+
+        for (i = 0; i < DTX_HANGOVER; i++)
+        {
+            L_temp = L_mac (L_temp, INV_DTX_HANGOVER_P1, lsf_old[i][j]);
+        }
+
+        lsf_aver[j] = extract_h (L_temp);              move16 (); 
+    }
+
+    return;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: update_gain_code_history_tx
+ *
+ *   PURPOSE: Update the fixed codebook gain parameter history of the
+ *            encoder. The fixed codebook gain parameters kept in the buffer
+ *            are used later for computing the reference fixed codebook
+ *            gain parameter value and the averaged fixed codebook gain
+ *            parameter value.
+ *
+ *   INPUTS:      new_gain_code   New fixed codebook gain value
+ *
+ *                gain_code_old_tx[0..4*DTX_HANGOVER-1]
+ *                                Old fixed codebook gain history of encoder
+ *
+ *   OUTPUTS:     gain_code_old_tx[0..4*DTX_HANGOVER-1]
+ *                                Updated fixed codebook gain history of encoder
+ *
+ *   RETURN VALUE: none
+ *
+ *************************************************************************/
+
+void update_gain_code_history_tx (
+    struct EFR_encoder_state *st,
+    Word16 new_gain_code
+)
+{
+    /* Circular buffer */
+    st->gain_code_old_tx[st->buf_p_tx] = new_gain_code;
+
+    if (sub (st->buf_p_tx, (4 * DTX_HANGOVER - 1)) == 0)
+    {
+        st->buf_p_tx = 0;
+    }
+    else
+    {
+        st->buf_p_tx = add (st->buf_p_tx, 1);
+    }
+
+    return;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: compute_CN_excitation_gain
+ *
+ *   PURPOSE: Compute the unquantized fixed codebook gain. Computation is
+ *            based on the energy of the Linear Prediction residual signal.
+ *
+ *   INPUTS:      res2[0..39]   Linear Prediction residual signal
+ *
+ *   OUTPUTS:     none
+ *
+ *   RETURN VALUE: Unquantized fixed codebook gain
+ *
+ *************************************************************************/
+
+Word16 compute_CN_excitation_gain (
+    Word16 res2[L_SUBFR]
+)
+{
+    Word16 i, norm, norm1, temp, overfl;
+    Word32 L_temp;
+
+    /* Compute the energy of the LP residual signal */
+
+    norm = 0;                                          move16 (); 
+    do
+    {
+        overfl = 0;                                    move16 ();
+
+        L_temp = 0L;                                   move32 (); 
+        for (i = 0; i < L_SUBFR; i++)
+        {
+            temp = shr (res2[i], norm);
+            L_temp = L_mac (L_temp, temp, temp);
+        }
+
+        test (); 
+        if (L_sub (L_temp, MAX_32) == 0)
+        {
+            norm = add (norm, 1);
+            overfl = 1;                 move16 (); /* Set the overflow flag */
+        }
+        test (); 
+    }
+    while (overfl != 0);
+
+    L_temp = L_add (L_temp, 1L);             /* Avoid the case of all zeros */
+
+    /* Take the square root of the obtained energy value (sqroot is a 2nd
+       order Taylor series approximation) */
+
+    norm1 = norm_l (L_temp);
+    temp = extract_h (L_shl (L_temp, norm1));
+    L_temp = L_mult (temp, temp);
+    L_temp = L_sub (805306368L, L_shr (L_temp, 3));
+    L_temp = L_add (L_temp, L_mult (24576, temp));
+
+    temp = extract_h (L_temp);
+    test (); logic16 (); 
+    if ((norm1 & 0x0001) != 0)
+    {
+        temp = mult_r (temp, 23170);
+        norm1 = sub (norm1, 1);
+    }
+    /* Divide the result of sqroot operation by sqroot(10) */
+
+    temp = mult_r (temp, 10362);
+
+    /* Re-scale to get the final value */
+
+    norm1 = shr (norm1, 1);
+    norm1 = sub (norm1, norm);
+
+    test (); 
+    if (norm1 >= 0)
+    {
+        temp = shr (temp, norm1);
+    }
+    else
+    {
+        temp = shl (temp, abs_s (norm1));
+    }
+
+    return temp;
+}
+
+/*************************************************************************
+ *
+ *   FUNCTION NAME: aver_gain_code_history
+ *
+ *   PURPOSE: Compute the averaged fixed codebook gain parameter value.
+ *            Computation is performed by averaging the fixed codebook
+ *            gain parameter values which exist in the fixed codebook
+ *            gain parameter history, together with the fixed codebook
+ *            gain parameter value of the current subframe.
+ *
+ *   INPUTS:      CN_excitation_gain
+ *                              Unquantized fixed codebook gain value
+ *                              of the current subframe
+ *                gain_code_old[0..4*DTX_HANGOVER-1]
+ *                              fixed codebook gain parameter history
+ *
+ *   OUTPUTS:     none
+ *
+ *   RETURN VALUE: Averaged fixed codebook gain value
+ *
+ *************************************************************************/
+
+Word16 aver_gain_code_history (
+    Word16 CN_excitation_gain,
+    Word16 gain_code_old[4 * DTX_HANGOVER]
+)
+{
+    Word16 i;
+    Word32 L_ret;
+
+    L_ret = L_mult (0x470, CN_excitation_gain);
+
+    for (i = 0; i < (4 * DTX_HANGOVER); i++)
+    {
+        L_ret = L_mac (L_ret, 0x470, gain_code_old[i]);
+    }
+    return extract_h (L_ret);
+}