view libgsmefr/dec_create.c @ 604:54f0f1b74c25

libgsmhr1 TFO: require BFI=0 and SID=0 for homing In order for a received frame to be recognized as DHF, we need not only the correct bit pattern, but also BFI=0 and SID=0. The BFI=0 requirement should be obvious, while the SID=0 requirement is needed only for HR codec. With FR and EFR, SID classification comes from the payload bits and no separate check is needed - but in HR we get an out-of-band SID ternary flag. When SID=1, no payload bits are used at all; when SID=2, we use only the first 33 bits of the payload. Therefore, it is proper to conditionalize DHF acceptance on SID=0. We already implemented this logic in the just finished full decoder; now bring TFO code into agreement.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 04 Dec 2025 19:40:35 +0000
parents 23656d874524
children
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/*
 * In this module we implement allocation and initialization
 * of state structures for our GSM EFR decoder.
 */

#include <stdlib.h>
#include "gsm_efr.h"
#include "typedef.h"
#include "cnst.h"
#include "dec_state.h"

const unsigned EFR_decoder_state_size = sizeof(struct EFR_decoder_state);

struct EFR_decoder_state *EFR_decoder_create(void)
{
	struct EFR_decoder_state *st;

	st = malloc(sizeof(struct EFR_decoder_state));
	if (st)
		EFR_decoder_reset(st);
	return st;
}