code.octet-stream.net Git - m17rt/blob - m17core/src/reflector/convert.rs

   1 //! Utilities for converting streams between UDP and RF representations
   2
   3 use crate::protocol::{LsfFrame, StreamFrame};
   4
   5 use super::packet::Voice;
   6
   7 /// Accepts `Voice` packets from a reflector and turns them into LSF and Stream frames.
   8 ///
   9 /// This is the format required for the voice data to cross the KISS protocol boundary.
  10 #[derive(Debug, Default)]
  11 pub struct VoiceToRf {
  12     /// Link Setup most recently acquired
  13     lsf: Option<LsfFrame>,
  14     /// Which LICH part we are going to emit next, 0-5
  15     lich_cnt: usize,
  16 }
  17
  18 impl VoiceToRf {
  19     pub fn new() -> Self {
  20         Self {
  21             lsf: None,
  22             lich_cnt: 0,
  23         }
  24     }
  25
  26     /// For a Voice packet received from a reflector, return the frames that would be transmitted
  27     /// on RF, including by reconstructing the LICH parts of the stream frame.
  28     ///
  29     /// If this is the start of a new or different stream transmission, this returns the Link Setup
  30     /// Frame which comes first, then the first associated Stream frame.
  31     ///
  32     /// If this is a continuation of a transmission matching the previous LSF, then it returns only
  33     /// the Stream frame.
  34     pub fn next(&mut self, voice: &Voice) -> (Option<LsfFrame>, StreamFrame) {
  35         let this_lsf = voice.link_setup_frame();
  36         let emit_lsf = if Some(&this_lsf) != self.lsf.as_ref() {
  37             self.lsf = Some(this_lsf.clone());
  38             self.lich_cnt = 0;
  39             true
  40         } else {
  41             false
  42         };
  43         let lsf = self.lsf.as_ref().unwrap();
  44         let stream = StreamFrame {
  45             lich_idx: self.lich_cnt as u8,
  46             lich_part: (&lsf.0[self.lich_cnt * 5..(self.lich_cnt + 1) * 5])
  47                 .try_into()
  48                 .unwrap(),
  49             frame_number: voice.frame_number(),
  50             end_of_stream: voice.is_end_of_stream(),
  51             stream_data: voice.payload().try_into().unwrap(),
  52         };
  53         let lsf = if emit_lsf { self.lsf.clone() } else { None };
  54         if voice.is_end_of_stream() {
  55             self.lsf = None;
  56         }
  57         (lsf, stream)
  58     }
  59 }
  60
  61 /// Accepts LSF and stream RF payloads and merges them into `Voice` packets for reflector use.
  62 ///
  63 /// For a series of transmissions this object should be re-used so that Stream ID is correctly
  64 /// changed after each new LSF.
  65 pub struct RfToVoice {
  66     lsf: LsfFrame,
  67     stream_id: u16,
  68 }
  69
  70 impl RfToVoice {
  71     pub fn new(lsf: LsfFrame) -> Self {
  72         Self { lsf, stream_id: 0 }
  73     }
  74
  75     pub fn process_lsf(&mut self, lsf: LsfFrame) {
  76         self.lsf = lsf;
  77         self.stream_id = self.stream_id.wrapping_add(1);
  78     }
  79
  80     pub fn process_stream(&self, stream: &StreamFrame) -> Voice {
  81         let mut v = Voice::new();
  82         v.set_stream_id(self.stream_id);
  83         v.set_frame_number(stream.frame_number);
  84         v.set_end_of_stream(stream.end_of_stream);
  85         v.set_payload(&stream.stream_data);
  86         v.set_link_setup_frame(&self.lsf);
  87         v
  88     }
  89 }
  90
  91 #[cfg(test)]
  92 mod tests {
  93     use crate::{
  94         address::{Address, Callsign},
  95         protocol::{LsfFrame, StreamFrame},
  96     };
  97
  98     use super::{RfToVoice, VoiceToRf};
  99
 100     #[test]
 101     fn convert_roundtrip() {
 102         let lsf = LsfFrame::new_voice(
 103             &Address::Callsign(Callsign(*b"VK7XT    ")),
 104             &Address::Broadcast,
 105         );
 106         let stream = StreamFrame {
 107             lich_idx: 0,
 108             lich_part: lsf.0[0..5].try_into().unwrap(),
 109             frame_number: 0,
 110             end_of_stream: false,
 111             stream_data: [1u8; 16],
 112         };
 113         let rf_to_voice = RfToVoice::new(lsf.clone());
 114         let voice = rf_to_voice.process_stream(&stream);
 115
 116         let mut voice_to_rf = VoiceToRf::new();
 117         let (lsf2, stream2) = voice_to_rf.next(&voice);
 118         assert_eq!(lsf2, Some(lsf));
 119         assert_eq!(stream2, stream);
 120     }
 121 }