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| author | Harald Welte <laforge@gnumonks.org> | 2016-12-31 20:44:42 +0100 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2017-01-01 19:51:50 +0100 |
| commit | 035e146029c443b6c1fa39d25524e5ee0f5f2916 (patch) | |
| tree | 216736b28c7bb76ac55a63ed943cfef71671ef16 | |
| parent | ce2f3967a03d2fbd9599f3945fee3a88d4ddb08e (diff) | |
fix DIAG timestamp conversion routines + add comments
| -rw-r--r-- | src/protocol.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/protocol.c b/src/protocol.c index d9d003f..1da7c13 100644 --- a/src/protocol.c +++ b/src/protocol.c @@ -39,12 +39,16 @@ uint32_t diag_ts_to_fn(uint64_t ts) return (ts/204800)%GSM_MAX_FN; } +/* DIAG timestamps consist of two parts: + * upper 48 bits: time since Jan 6 1980 00:00:00 (GPS) in 1.25ms units + * lower 16 bits: time since last 1.25ms tick in 1/32 chip units */ uint32_t diag_ts_to_epoch(uint64_t qd_time) { double qd_ts; - qd_ts = osmo_load64le(&qd_time); - qd_ts *= 1.25*256.0/1000.0; + qd_ts = osmo_load64le(&qd_time) >> 16; + qd_ts *= 1.25; + qd_ts /= 1000.0; /* Sanity check on timestamp (year > 2011) */ if (qd_ts < 1000000000) { @@ -56,7 +60,8 @@ uint32_t diag_ts_to_epoch(uint64_t qd_time) if (0 == rv) return tv.tv_sec; } else { - /* Adjust timestamp from GPS to UNIX */ + /* Adjust timestamp from GPS to UNIX, i.e. number of + * seconds between 1970 and Jan 6 1980 */ qd_ts += 315964800.0; } |