67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
#include <assert.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include "common.h"
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#include "airspy_adsb.h"
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struct airspy_adsb_parser_state {
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uint64_t mlat_timestamp_last;
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uint64_t mlat_timestamp_generation;
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};
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static bool airspy_adsb_parse_common(char *, struct packet *, struct airspy_adsb_parser_state *);
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void airspy_adsb_init() {
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assert(sizeof(struct airspy_adsb_parser_state) <= PARSER_STATE_LEN);
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}
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bool airspy_adsb_parse(struct backend *backend, struct packet *packet) {
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struct buf *buf = &backend->buf;
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struct airspy_adsb_parser_state *state = (struct airspy_adsb_parser_state *) backend->parser_state;
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if (buf->length < 35 ||
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buf_chr(buf, 0) != '*') {
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return false;
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}
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if (buf->length >= 35 &&
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buf_chr(buf, 33) == '\r' &&
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buf_chr(buf, 34) == '\n' &&
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buf_chr(buf, 15) == ';') {
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if (!airspy_adsb_parse_common(buf_at(buf, 16), packet, state)) {
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return false;
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}
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packet->type = MODE_S_SHORT;
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hex_to_bin(packet->data, buf_at(buf, 1), 7);
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buf_consume(buf, 35);
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return true;
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}
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if (buf->length >= 49 &&
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buf_chr(buf, 47) == '\r' &&
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buf_chr(buf, 48) == '\n' &&
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buf_chr(buf, 29) == ';') {
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if (!airspy_adsb_parse_common(buf_at(buf, 30), packet, state)) {
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return false;
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}
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packet->type = MODE_S_LONG;
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hex_to_bin(packet->data, buf_at(buf, 1), 14);
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buf_consume(buf, 49);
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return true;
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}
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return false;
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}
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static bool airspy_adsb_parse_common(char *in, struct packet *packet, struct airspy_adsb_parser_state *state) {
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if (in[8] != ';' ||
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in[11] != ';' ||
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in[16] != ';') {
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return false;
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}
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uint16_t mlat_mhz = 2 * hex_to_int(&in[9], 1);
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packet->mlat_timestamp = hex_to_int(in, 4) * (MLAT_MHZ / mlat_mhz);
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packet->rssi = hex_to_int(&in[12], 2) * (RSSI_MAX / UINT16_MAX);
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return true;
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}
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