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 }