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Overhaul mode A/C matching to be much cheaper.

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The old matching process which tracked mode A values as pseudo-aircraft
got very, very expensive with a large number of mode A/C messages (and
with lots of single-bit errors, which seems common with a Beast doing
the reception)

Instead just count A/C messages directly into a 4096-entry array (which
is very fast) and periodically scan the mode S aircraft list to see if
we can match anything up (which is fixed overhead + cost proportional
to the number of mode S aircraft)
This commit is contained in:
Oliver Jowett 2016-10-11 18:00:11 +01:00
parent 60f1f3bcb6
commit 25ea6d398b
6 changed files with 111 additions and 140 deletions
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6
dump1090.h
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@ -105,12 +105,6 @@ typedef struct rtlsdr_dev rtlsdr_dev_t;
#define MODEAC_MSG_SAMPLES (25 * 2) // include up to the SPI bit
#define MODEAC_MSG_BYTES 2
#define MODEAC_MSG_SQUELCH_LEVEL 0x07FF // Average signal strength limit
#define MODEAC_MSG_FLAG (1<<0)
#define MODEAC_MSG_MODES_HIT (1<<1)
#define MODEAC_MSG_MODEA_HIT (1<<2)
#define MODEAC_MSG_MODEC_HIT (1<<3)
#define MODEAC_MSG_MODEA_ONLY (1<<4)
#define MODEAC_MSG_MODEC_OLD (1<<5)
#define MODES_PREAMBLE_US 8 // microseconds = bits
#define MODES_PREAMBLE_SAMPLES (MODES_PREAMBLE_US * 2)