--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/decoder.c	Wed Apr 03 05:31:37 2024 +0000
@@ -0,0 +1,218 @@
+/***************************************************************************
+ *
+ *  FILE NAME:  decoder.c
+ *
+ *         Usage : decoder  bitstream_file  synth_file
+ *
+ *         Format for bitstream_file:
+ *           One word (2-byte) for bad frame indication (BFI) flag bit
+ *               0x0000 -> good frame;  0x0001 -> bad frame
+ *           244  words (2-byte) containing 244 bits.
+ *               Bit 0 = 0x0000 and Bit 1 = 0x0001
+ *           One word (2-byte) for ternary Silence Descriptor (SID) flag
+ *               0x0000 -> inactive (no detected speech activity);
+ *               0x0001 -> active
+ *           One word (2-byte) for Time Alignment Flag (TAF) bit
+ *               0x0000 -> inactive (no transmission of speech frames);
+ *               0x0001 -> active
+ *
+ *         Format for synth_file:
+ *           Synthesis is written to a binary file of 16 bits data.
+ *
+ ***************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "typedef.h"
+#include "n_stack.h"
+#include "basic_op.h"
+#include "sig_proc.h"
+#include "count.h"
+#include "codec.h"
+#include "cnst.h"
+#include "d_homing.h"
+
+
+/* These constants define the number of consecutive parameters
+   that function decoder_homing_frame_test() checks */
+
+#define WHOLE_FRAME 57
+#define TO_FIRST_SUBFRAME 18
+
+
+Word16 synth_buf[L_FRAME + M];
+
+/* L_FRAME, M, PRM_SIZE, AZ_SIZE, SERIAL_SIZE: defined in "cnst.h" */
+
+/*-----------------------------------------------------------------*
+ *             Global variables                                    *
+ *-----------------------------------------------------------------*/
+
+#if (WMOPS)
+Word16 dtx_mode = 0;
+
+#endif
+
+/*-----------------------------------------------------------------*
+ *            Main decoder routine                                 *
+ *-----------------------------------------------------------------*/
+
+int 
+main (int argc, char *argv[])
+{
+    Word16 *synth;              /* Synthesis                  */
+    Word16 parm[PRM_SIZE + 1];  /* Synthesis parameters       */
+    Word16 serial[SERIAL_SIZE+2];/* Serial stream              */
+    Word16 Az_dec[AZ_SIZE];     /* Decoded Az for post-filter */
+                                /* in 4 subframes, length= 44 */
+    Word16 i, frame, temp;
+    FILE *f_syn, *f_serial;
+
+    Word16 TAF, SID_flag;
+
+    Word16 reset_flag;
+    static Word16 reset_flag_old = 1;
+
+    proc_head ("Decoder");
+
+    /*-----------------------------------------------------------------*
+     *           Read passed arguments and open in/out files           *
+     *-----------------------------------------------------------------*/
+
+    if (argc != 3)
+    {
+        fprintf (stderr,
+                 "   Usage:\n\n   decoder  bitstream_file  synth_file\n");
+        fprintf (stderr, "\n");
+        exit (1);
+    }
+    /* Open file for synthesis and packed serial stream */
+
+    if ((f_serial = fopen (argv[1], "rb")) == NULL)
+    {
+        fprintf (stderr, "Input file '%s' does not exist !!\n", argv[1]);
+        exit (0);
+    }
+    else
+        fprintf (stderr, "Input bitstream file:   %s\n", argv[1]);
+
+    if ((f_syn = fopen (argv[2], "wb")) == NULL)
+    {
+        fprintf (stderr, "Cannot open file '%s' !!\n", argv[2]);
+        exit (0);
+    }
+    else
+        fprintf (stderr, "Synthesis speech file:   %s\n", argv[2]);
+
+    /*-----------------------------------------------------------------*
+     *           Initialization of decoder                             *
+     *-----------------------------------------------------------------*/
+
+    synth = synth_buf + M;
+
+    reset_dec (); /* Bring the decoder and receive DTX to the initial state */
+
+#if (WMOPS)
+    Init_WMOPS_counter ();
+#endif
+
+    /*-----------------------------------------------------------------*
+     *            Loop for each "L_FRAME" speech data                  *
+     *-----------------------------------------------------------------*/
+
+    frame = 0;
+
+    while (fread (serial, sizeof (Word16), 247, f_serial) == 247)
+    {
+#if (WMOPS)
+        fprintf (stderr, "frame=%d  ", ++frame);
+#else
+        fprintf (stderr, "\nframe=%d  ", ++frame);
+#endif
+
+#if (WMOPS)
+        Reset_WMOPS_counter (); /* reset WMOPS counter for the new frame */
+#endif
+
+        SID_flag = serial[245];         /* Receive SID flag */
+        TAF = serial[246];              /* Receive TAF flag */
+
+        Bits2prm_12k2 (serial, parm);   /* serial to parameters   */
+
+#if (WMOPS)
+        fwc ();                         /* function worst case */
+#endif
+
+        if (parm[0] == 0)               /* BFI == 0, perform DHF check */
+        {
+            if (reset_flag_old == 1)    /* Check for second and further
+                                           successive DHF (to first subfr.) */
+            {
+                reset_flag = decoder_homing_frame_test (&parm[1],
+                                                        TO_FIRST_SUBFRAME);
+            }
+            else
+            {
+                reset_flag = 0;
+            }
+        }
+        else                          /* BFI==1, bypass DHF check (frame
+                                           is taken as not being a DHF) */
+        {
+            reset_flag = 0;
+        }
+
+        if ((reset_flag != 0) && (reset_flag_old != 0))
+        {
+            /* Force the output to be the encoder homing frame pattern */
+
+            for (i = 0; i < L_FRAME; i++)
+            {
+                synth[i] = EHF_MASK;
+            }
+        }
+        else
+        {
+            Decoder_12k2 (parm, synth, Az_dec, TAF, SID_flag);/* Synthesis */
+
+            Post_Filter (synth, Az_dec);                      /* Post-filter */
+#if (WMOPS)
+            fwc ();             /* function worst case */
+#endif
+
+            for (i = 0; i < L_FRAME; i++) 
+                /* Upscale the 15 bit linear PCM to 16 bits,
+                   then truncate to 13 bits */
+            {
+                temp = shl (synth[i], 1);
+                synth[i] = temp & 0xfff8;       logic16 (); move16 (); 
+            }
+
+#if (WMOPS)
+            fwc ();                             /* function worst case */
+#endif
+
+#if (WMOPS)
+            WMOPS_output (dtx_mode);/* output WMOPS values for current frame */
+#endif
+        }                       /* else */
+
+        fwrite (synth, sizeof (Word16), L_FRAME, f_syn);
+
+        /* BFI == 0, perform check for first DHF (whole frame) */
+        if ((parm[0] == 0) && (reset_flag_old == 0))
+        {
+            reset_flag = decoder_homing_frame_test (&parm[1], WHOLE_FRAME);
+        }
+
+        if (reset_flag != 0)
+        {
+            /* Bring the decoder and receive DTX to the home state */
+            reset_dec ();
+        }
+        reset_flag_old = reset_flag;
+
+    }                           /* while */
+
+    return 0;
+}