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.

/*
 * Here we implement our binfile_read_frame() function.
 */

#include <stdio.h>
#include <stdint.h>
#include "binreader.h"

int binfile_read_frame(FILE *binf, uint8_t *frame)
{
	int cc, morelen;

	cc = fread(frame, 1, 1, binf);
	if (cc != 1)
		return 0;
	if (frame[0] == 0xBF)
		morelen = 1;
	else if ((frame[0] & 0xF0) == 0xC0)
		morelen = 30;
	else if ((frame[0] & 0xF0) == 0xD0)
		morelen = 32;
	else
		return -1;
	cc = fread(frame+1, 1, morelen, binf);
	if (cc == morelen)
		return 1;
	else
		return -2;
}