nmea_kit/ais/messages/
position_b.rs

1//! AIS position report — Type 18 (Class B standard).
2
3use crate::ais::armor::{extract_i32, extract_u32};
4
5use super::common::AisClass;
6use super::position_a::PositionReport;
7use super::utils::{decode_cog, decode_heading, decode_latitude, decode_longitude, decode_sog};
8
9impl PositionReport {
10    /// Decode a Type 18 Class B standard position report.
11    pub fn decode_class_b(bits: &[u8]) -> Option<Self> {
12        if bits.len() < 168 {
13            return None;
14        }
15
16        let msg_type = extract_u32(bits, 0, 6)? as u8;
17        let mmsi = extract_u32(bits, 8, 30)?;
18        let sog_raw = extract_u32(bits, 46, 10)?;
19        let accuracy = extract_u32(bits, 56, 1)? == 1;
20        let lon_raw = extract_i32(bits, 57, 28)?;
21        let lat_raw = extract_i32(bits, 85, 27)?;
22        let cog_raw = extract_u32(bits, 112, 12)?;
23        let hdg_raw = extract_u32(bits, 124, 9)?;
24        let ts_raw = extract_u32(bits, 133, 6)? as u8;
25
26        Some(Self {
27            msg_type,
28            mmsi,
29            nav_status: None,
30            rate_of_turn: None,
31            sog: decode_sog(sog_raw),
32            position_accuracy: accuracy,
33            longitude: decode_longitude(lon_raw),
34            latitude: decode_latitude(lat_raw),
35            cog: decode_cog(cog_raw),
36            heading: decode_heading(hdg_raw),
37            timestamp: if ts_raw < 60 { Some(ts_raw) } else { None },
38            ais_class: AisClass::B,
39        })
40    }
41}
nmea_kit/ais/messages/position_b.rs

nmea_kit/ais/messages/
position_b.rs
