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.

/*
 * This C module is our current best attempt at determining the local endian
 * in a portable manner that (hopefully) won't come back to bite us when
 * someone needs to compile our software under a different flavor of Unix.
 */

#include <stdint.h>
#include <arpa/inet.h>
#include "local_endian.h"

int is_native_big_endian(void)
{
	uint16_t big_end_one;

	big_end_one = htons(1);
	if (big_end_one == 1)
		return 1;
	else
		return 0;
}