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