/*
 * This module contains our GSM EFR decoder main function, EFR_decode_params(),
 * that stands at the boundary between our public interface and the guts of
 * ETSI-based codec.
 */

#include "gsm_efr.h"
#include "typedef.h"
#include "namespace.h"
#include "basic_op.h"
#include "cnst.h"
#include "codec.h"
#include "sig_proc.h"
#include "memops.h"
#include "dec_state.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

void EFR_decode_params(struct EFR_decoder_state *st, const int16_t *params,
			int bfi, int SID_flag, int TAF, int16_t *pcm_out)
{
	Word16 *synth = st->synth_buf + M;
	Word16 Az_dec[AZ_SIZE];
	Word16 i, temp;
	Word16 reset_flag;

        if (!bfi)                       /* BFI == 0, perform DHF check */
        {
            if (st->reset_flag_old)     /* Check for second and further
                                           successive DHF (to first subfr.) */
            {
                reset_flag = decoder_homing_frame_test (params,
                                                        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 && st->reset_flag_old)
        {
            /* Force the output to be the encoder homing frame pattern */

            for (i = 0; i < L_FRAME; i++)
            {
                synth[i] = EHF_MASK;
            }
        }
        else
        {
            /* Synthesis */
            Decoder_12k2 (st, bfi, params, synth, Az_dec, TAF, SID_flag);

            Post_Filter (st, synth, Az_dec);                  /* Post-filter */

            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;
            }
        }                       /* else */

        Copy (synth, pcm_out, L_FRAME);

        /* BFI == 0, perform check for first DHF (whole frame) */
        if (!bfi && !st->reset_flag_old)
        {
            reset_flag = decoder_homing_frame_test (params, WHOLE_FRAME);
        }

        if (reset_flag)
        {
            /* Bring the decoder and receive DTX to the home state */
            EFR_decoder_reset(st);
        } else {
            st->reset_flag_old = 0;
        }
}