libgsmfrp: new refined implementation The previous implementation exhibited the following defects, which are now fixed: 1) The last received valid SID was cached forever for the purpose of handling future invalid SIDs - we could have received some valid SID ages ago, then lots of speech or NO_DATA, and if we then get an invalid SID, we would resurrect the last valid SID from ancient history - a bad design. In our new design, we handle invalid SID based on the current state, much like BFI. 2) GSM 06.11 spec says clearly that after the second lost SID (received BFI=1 && TAF=1 in CN state) we need to gradually decrease the output level, rather than jump directly to emitting silence frames - we previously failed to implement such logic. 3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes in a SID frame. What should we do if we receive an otherwise valid SID frame with different Xmaxc? Our previous approach would replicate this Xmaxc oddity in every subsequent generated CN frame, which is rather bad. In our new design, the very first CN frame (which can be seen as a transformation of the SID frame itself) retains the original 4 distinct Xmaxc, but all subsequent CN frames are based on the Xmaxc from the last subframe of the most recent SID.

/*
 * The original ETSI EFR code features an include file named q_plsf_5.tab,
 * included into d_homing.c, d_plsf_5.c and q_plsf_5.c, duplicating
 * the small mean_lsf[] table across all 3 modules and the other (big)
 * tables across d_plsf_5.c for the decoder and q_plsf_5.c for the encoder.
 *
 * In our version we have moved the tables into q_plsf5_tab.c,
 * with extern declarations in q_plsf5_tab.h.
 */

extern const Word16 mean_lsf[10];

#define DICO1_SIZE  128
#define DICO2_SIZE  256
#define DICO3_SIZE  256
#define DICO4_SIZE  256
#define DICO5_SIZE  64

extern const Word16 dico1_lsf[DICO1_SIZE * 4];
extern const Word16 dico2_lsf[DICO2_SIZE * 4];
extern const Word16 dico3_lsf[DICO3_SIZE * 4];
extern const Word16 dico4_lsf[DICO4_SIZE * 4];
extern const Word16 dico5_lsf[DICO5_SIZE * 4];