diff options
| -rw-r--r-- | src/encoding.cpp | 74 |
1 files changed, 43 insertions, 31 deletions
diff --git a/src/encoding.cpp b/src/encoding.cpp index 7d3fa144..fb80eeba 100644 --- a/src/encoding.cpp +++ b/src/encoding.cpp @@ -35,6 +35,43 @@ extern "C" { #include <errno.h> #include <string.h> +/* { 0 | 1 < TIMING_ADVANCE_INDEX : bit (4) > } */ +static inline bool write_tai(bitvec *dest, unsigned& wp, int8_t tai) +{ + if (tai < 0) { /* No TIMING_ADVANCE_INDEX: */ + bitvec_write_field(dest, wp, 0, 1); + return false; + } + /* TIMING_ADVANCE_INDEX: */ + bitvec_write_field(dest, wp, 1, 1); + bitvec_write_field(dest, wp, tai, 4); + return true; +} + +/* { 0 | 1 < TIMING_ADVANCE_VALUE : bit (6) > } */ +static inline void write_ta(bitvec *dest, unsigned& wp, int8_t ta) +{ + if (ta < 0) /* No TIMING_ADVANCE_VALUE: */ + bitvec_write_field(dest, wp, 0, 1); + else { /* TIMING_ADVANCE_VALUE: */ + bitvec_write_field(dest, wp, 1, 1); + bitvec_write_field(dest, wp, ta, 6); + } +} + +/* 3GPP TS 44.060 ยง 12.12: + { 0 | 1 < TIMING_ADVANCE_VALUE : bit (6) > } + { 0 | 1 < TIMING_ADVANCE_INDEX : bit (4) > + < TIMING_ADVANCE_TIMESLOT_NUMBER : bit (3) > } + */ +static inline void write_ta_ie(bitvec *dest, unsigned& wp, + int8_t ta, int8_t tai, uint8_t ts) +{ + write_ta(dest, wp, ta); + if (write_tai(dest, wp, tai)) /* TIMING_ADVANCE_TIMESLOT_NUMBER: */ + bitvec_write_field(dest, wp, ts, 3); +} + static int write_ia_rest_downlink( gprs_rlcmac_dl_tbf *tbf, bitvec * dest, unsigned& wp, @@ -62,12 +99,7 @@ static int write_ia_rest_downlink( bitvec_write_field(dest, wp,gamma,5); // GAMMA power control parameter bitvec_write_field(dest, wp,polling,1); // Polling Bit bitvec_write_field(dest, wp, ta_valid, 1); // N. B: NOT related to TAI! - if (ta_idx < 0) { - bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off - } else { - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_INDEX = on - bitvec_write_field(dest, wp,ta_idx,4); // TIMING_ADVANCE_INDEX - } + write_tai(dest, wp, ta_idx); if (polling) { bitvec_write_field(dest, wp,0x1,1); // TBF Starting TIME present bitvec_write_field(dest, wp,(fn / (26 * 51)) % 32,5); // T1' @@ -110,12 +142,7 @@ static int write_ia_rest_uplink( } else bitvec_write_field(dest, wp,0x0,1); // ALPHA = not present bitvec_write_field(dest, wp,gamma,5); // GAMMA power control parameter - if (ta_idx < 0) { - bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off - } else { - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_INDEX = on - bitvec_write_field(dest, wp,ta_idx,4); // TIMING_ADVANCE_INDEX - } + write_tai(dest, wp, ta_idx); bitvec_write_field(dest, wp, 1, 1); // TBF_STARTING_TIME_FLAG bitvec_write_field(dest, wp,(fn / (26 * 51)) % 32,5); // T1' bitvec_write_field(dest, wp,fn % 51,6); // T3 @@ -311,6 +338,8 @@ void Encoding::write_packet_uplink_assignment( // TODO We should use our implementation of encode RLC/MAC Control messages. unsigned wp = 0; uint8_t ts; + /* timeslot assigned for the Continuous Timing Advance procedure */ + uint8_t ta_ts = 0; /* FIXME: supply it as parameter from caller */ bitvec_write_field(dest, wp,0x1,2); // Payload Type bitvec_write_field(dest, wp,0x0,2); // Uplink block with TDMA framenumber (N+13) @@ -334,15 +363,7 @@ void Encoding::write_packet_uplink_assignment( bitvec_write_field(dest, wp,0x0,1); // Message escape bitvec_write_field(dest, wp,tbf->current_cs().to_num()-1, 2); // CHANNEL_CODING_COMMAND bitvec_write_field(dest, wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on - bitvec_write_field(dest, wp,tbf->ta(),6); // TIMING_ADVANCE_VALUE - if (ta_idx < 0) { - bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off - } else { - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_INDEX = on - bitvec_write_field(dest, wp,ta_idx,4); // TIMING_ADVANCE_INDEX - } - + write_ta_ie(dest, wp,tbf->ta(), ta_idx, ta_ts); } else { /* EPGRS */ unsigned int ws_enc = (tbf->m_window.ws() - 64) / 32; bitvec_write_field(dest, wp,0x1,1); // Message escape @@ -357,16 +378,7 @@ void Encoding::write_packet_uplink_assignment( bitvec_write_field(dest, wp,0x0,1); // No ARAC RETRANSMISSION REQUEST bitvec_write_field(dest, wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING bitvec_write_field(dest, wp,0x0,1); // No BEP_PERIOD2 - - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on - bitvec_write_field(dest, wp,tbf->ta(),6); // TIMING_ADVANCE_VALUE - if (ta_idx < 0) { - bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off - } else { - bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_INDEX = on - bitvec_write_field(dest, wp,ta_idx,4); // TIMING_ADVANCE_INDEX - } - + write_ta_ie(dest, wp,tbf->ta(), ta_idx, ta_ts); bitvec_write_field(dest, wp,0x0,1); // No Packet Extended Timing Advance } |