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 header file contains some common definitions that have been
 * factored out of dtx_enc.h; the original code used the construct of
 * dtx_dec.h including dtx_enc.h, but in the opinion of this developer
 * it is better to factor out the common bits.
 */

#ifndef dtx_common_h
#define dtx_common_h
 
/*
********************************************************************************
*                         LOCAL VARIABLES AND TABLES
********************************************************************************
*/
#define DTX_HIST_SIZE 8
#define DTX_ELAPSED_FRAMES_THRESH (24 + 7 -1)
#define DTX_HANG_CONST 7             /* yields eight frames of SP HANGOVER  */

#endif