nmea_kit/ais/messages/
position_a.rs

1//! AIS position report — Types 1, 2, 3 (Class A).
2
3use crate::ais::armor::{extract_i32, extract_u32};
4
5use super::common::{AisClass, NavigationStatus};
6use super::utils::{
7    decode_cog, decode_heading, decode_latitude, decode_longitude, decode_rot, decode_sog,
8};
9
10/// AIS Position Report — Types 1, 2, 3 (Class A) and 18 (Class B) and 19 (B+).
11#[derive(Debug, Clone, PartialEq)]
12pub struct PositionReport {
13    pub msg_type: u8,
14    pub mmsi: u32,
15    pub nav_status: Option<NavigationStatus>,
16    pub rate_of_turn: Option<f32>,
17    pub sog: Option<f32>,
18    pub position_accuracy: bool,
19    pub longitude: Option<f64>,
20    pub latitude: Option<f64>,
21    pub cog: Option<f32>,
22    /// True heading in degrees (integer, 0-359). AIS has no fractional resolution for heading.
23    pub heading: Option<u16>,
24    pub timestamp: Option<u8>,
25    pub ais_class: AisClass,
26}
27
28impl PositionReport {
29    /// Decode a Type 1/2/3 Class A position report from AIS bits.
30    pub fn decode_class_a(bits: &[u8]) -> Option<Self> {
31        if bits.len() < 168 {
32            return None;
33        }
34
35        let msg_type = extract_u32(bits, 0, 6)? as u8;
36        let mmsi = extract_u32(bits, 8, 30)?;
37        let nav_status_raw = extract_u32(bits, 38, 4)? as u8;
38        let rot_raw = extract_i32(bits, 42, 8)?;
39        let sog_raw = extract_u32(bits, 50, 10)?;
40        let accuracy = extract_u32(bits, 60, 1)? == 1;
41        let lon_raw = extract_i32(bits, 61, 28)?;
42        let lat_raw = extract_i32(bits, 89, 27)?;
43        let cog_raw = extract_u32(bits, 116, 12)?;
44        let hdg_raw = extract_u32(bits, 128, 9)?;
45        let ts_raw = extract_u32(bits, 137, 6)? as u8;
46
47        Some(Self {
48            msg_type,
49            mmsi,
50            nav_status: Some(NavigationStatus::from(nav_status_raw)),
51            rate_of_turn: decode_rot(rot_raw),
52            sog: decode_sog(sog_raw),
53            position_accuracy: accuracy,
54            longitude: decode_longitude(lon_raw),
55            latitude: decode_latitude(lat_raw),
56            cog: decode_cog(cog_raw),
57            heading: decode_heading(hdg_raw),
58            timestamp: if ts_raw < 60 { Some(ts_raw) } else { None },
59            ais_class: AisClass::A,
60        })
61    }
62}
nmea_kit/ais/messages/position_a.rs

nmea_kit/ais/messages/
position_a.rs
