--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/e_homing.c	Wed Apr 03 05:31:37 2024 +0000
@@ -0,0 +1,163 @@
+/**************************************************************************
+ *
+ *   File Name:  e_homing.c
+ *
+ *   Purpose:
+ *      This file contains the following functions:
+ *
+ *      encoder_homing_frame_test()  checks if a frame of input samples
+ *                                   matches the Encoder Homing Frame pattern.
+ *
+ *      encoder_reset()              called by reset_enc() to reset all
+ *                                   the state variables for the encoder.
+ *
+ *      reset_enc()                  calls functions to reset the state
+ *                                   variables for the encoder and VAD, and
+ *                                   for the transmit DTX and Comfort Noise.
+ *
+ **************************************************************************/
+
+#include "typedef.h"
+#include "cnst.h"
+#include "vad.h"
+#include "dtx.h"
+#include "codec.h"
+#include "sig_proc.h"
+#include "e_homing.h"
+
+/***************************************************************************
+ *
+ *   FUNCTION NAME:  encoder_homing_frame_test
+ *
+ *   PURPOSE:
+ *      Checks if a frame of input samples matches the Encoder Homing Frame
+ *      pattern, which is 0x0008 for all 160 samples in the frame.
+ *
+ *   INPUT:
+ *      input_frame[]    one frame of speech samples
+ *
+ *   OUTPUT:
+ *      None
+ *
+ *   RETURN:
+ *      0       input frame does not match the Encoder Homing Frame pattern.
+ *      1       input frame matches the Encoder Homing Frame pattern.
+ *
+ **************************************************************************/
+
+Word16 encoder_homing_frame_test (Word16 input_frame[])
+{
+    Word16 i, j;
+
+    for (i = 0; i < L_FRAME; i++)
+    {
+        j = input_frame[i] ^ EHF_MASK;
+
+        if (j)
+            break;
+    }
+
+    return !j;
+}
+
+/***************************************************************************
+ *
+ *   FUNCTION NAME:  encoder_reset
+ *
+ *   PURPOSE:
+ *      resets all of the state variables for the encoder
+ *
+ *   INPUT:
+ *      None
+ *
+ *   OUTPUT:
+ *      None
+ *
+ *   RETURN:
+ *      None
+ *
+ **************************************************************************/
+
+void encoder_reset (void)
+{
+    /* External declarations for encoder variables which need to be reset */
+
+    /* Variables defined in levinson.c */
+    /* ------------------------------- */
+    extern Word16 old_A[M + 1]; /* Last A(z) for case of unstable filter */
+
+    /* Variables defined in q_gains.c */
+    /* ------------------------------- */
+    /* Memories of gain quantization: */
+    extern Word16 past_qua_en[4], pred[4];
+
+    /* Variables defined in q_plsf_5.c */
+    /* ------------------------------- */
+    /* Past quantized prediction error */
+    extern Word16 past_r2_q[M];
+
+    Word16 i;
+
+    /* reset all the encoder state variables */
+    /* ------------------------------------- */
+
+    /* Variables in cod_12k2.c: */
+    Init_Coder_12k2 ();
+
+    /* Variables in levinson.c: */
+    old_A[0] = 4096;            /* Last A(z) for case of unstable filter */
+    for (i = 1; i < M + 1; i++)
+    {
+        old_A[i] = 0;
+    }
+
+    /* Variables in pre_proc.c: */
+    Init_Pre_Process ();
+
+    /* Variables in q_gains.c: */
+    for (i = 0; i < 4; i++)
+    {
+        past_qua_en[i] = -2381; /* past quantized energies */
+    }
+
+    pred[0] = 44;               /* MA prediction coeff */
+    pred[1] = 37;               /* MA prediction coeff */
+    pred[2] = 22;               /* MA prediction coeff */
+    pred[3] = 12;               /* MA prediction coeff */
+
+    /* Variables in q_plsf_5.c: */
+    for (i = 0; i < M; i++)
+    {
+        past_r2_q[i] = 0;       /* Past quantized prediction error */
+    }
+
+    return;
+}
+
+/***************************************************************************
+ *
+ *   FUNCTION NAME:  reset_enc
+ *
+ *   PURPOSE:
+ *      resets all of the state variables for the encoder and VAD, and for
+ *      the transmit DTX and Comfort Noise.
+ *
+ *   INPUT:
+ *      None
+ *
+ *   OUTPUT:
+ *      None
+ *
+ *   RETURN:
+ *      None
+ *
+ **************************************************************************/
+
+void reset_enc (void)
+{
+    encoder_reset (); /* reset all the state variables in the speech encoder*/
+    vad_reset ();     /* reset all the VAD state variables */
+    reset_tx_dtx ();  /* reset all the transmit DTX and CN variables */
+
+    return;
+}