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.

/*
 * The helper function implemented in this module emits TW-TS-005 Annex B
 * hex output based on an encoder output array, i.e., a cod-style frame.
 * This helper function will be used for gsmhr-cod2hex, gsmhr-encode[-r]
 * and gsmhr-tfo-xfrm utilities.
 */

#include <stdint.h>
#include <stdio.h>
#include "../libgsmhr1/tw_gsmhr.h"
#include "../libtest/tw5writer.h"

void
emit_cod_to_tw5b(outf, params, emit_5993)
	FILE *outf;
	int16_t *params;
{
	uint8_t frame[GSMHR_FRAME_LEN_5993];

	gsmhr_encoder_twts002_out(params, frame);
	if (emit_5993)
		emit_hex_frame(outf, frame, GSMHR_FRAME_LEN_5993);
	else
		emit_hex_frame(outf, frame + 1, GSMHR_FRAME_LEN_RPF);
}