-use crate::kiss::{KissBuffer, KissFrame};
-use crate::protocol::{Frame, LichCollection, LsfFrame};
+use crate::kiss::{KissBuffer, KissFrame, PORT_PACKET_BASIC, PORT_PACKET_FULL, PORT_STREAM};
+use crate::modem::ModulatorFrame;
+use crate::protocol::{
+ Frame, LichCollection, LsfFrame, Mode, PacketFrame, PacketFrameCounter, StreamFrame,
+};
/// Handles the KISS protocol and frame management for `SoftModulator` and `SoftDemodulator`.
///
/// Current RX or TX function of the TNC.
state: State,
+
+ /// Latest state of data carrier detect from demodulator - controls whether we can go to TX
+ dcd: bool,
+
+ /// Current monotonic time, counted in samples
+ now: u64,
+
+ // TODO: use a static ring buffer crate of some sort?
+ /// Circular buffer of packets enqueued for transmission
+ packet_queue: [PendingPacket; 4],
+
+ /// Next slot to fill
+ packet_next: usize,
+
+ /// Current packet index, which is either partly transmitted or not transmitted at all.
+ packet_curr: usize,
+
+ /// If true, packet_next == packet_curr implies full queue. packet_next is invalid.
+ /// If false, it implies empty queue.
+ packet_full: bool,
+
+ /// The LSF for a stream we are going to start transmitting.
+ ///
+ /// This serves as a general indicator that we want to tx a stream.
+ stream_pending_lsf: Option<LsfFrame>,
+
+ /// Circular buffer of stream data enqueued for transmission.
+ ///
+ /// When the queue empties out, we hope that the last one has the end-of-stream flag set.
+ /// Otherwise a buffer underrun has occurred.
+ ///
+ /// Overruns are less troublesome - we can drop frames and receiving stations should cope.
+ stream_queue: [StreamFrame; 8],
+
+ /// Next slot to fill
+ stream_next: usize,
+
+ /// Current unsent stream frame index
+ stream_curr: usize,
+
+ /// True if stream_next == stream_curr because the queue is full. stream_next is invalid.
+ stream_full: bool,
+
+ /// Should PTT be on right now? Polled by external
+ ptt: bool,
}
impl SoftTnc {
kiss_buffer: KissBuffer::new(),
outgoing_kiss: None,
state: State::Idle,
+ dcd: false,
+ now: 0,
+ packet_queue: Default::default(),
+ packet_next: 0,
+ packet_curr: 0,
+ packet_full: false,
+ stream_pending_lsf: None,
+ stream_queue: Default::default(),
+ stream_next: 0,
+ stream_curr: 0,
+ stream_full: false,
+ ptt: false,
}
}
/// Process an individual `Frame` that has been decoded by the modem.
- pub fn handle_frame(&mut self, _frame: Frame) -> Result<(), SoftTncError> {
- Ok(())
+ pub fn handle_frame(&mut self, frame: Frame) {
+ match frame {
+ Frame::Lsf(lsf) => {
+ // A new LSF implies a clean slate.
+ // If we were partway through decoding something else then we missed it.
+ match lsf.mode() {
+ Mode::Packet => {
+ self.state = State::RxPacket(RxPacketState {
+ lsf,
+ packet: [0u8; 825],
+ count: 0,
+ })
+ }
+ Mode::Stream => {
+ let kiss = KissFrame::new_stream_setup(&lsf.0).unwrap();
+ self.kiss_to_host(kiss);
+ self.state = State::RxStream(RxStreamState { lsf, index: 0 });
+ }
+ }
+ }
+ Frame::Packet(packet) => {
+ match &mut self.state {
+ State::RxPacket(ref mut rx) => {
+ match packet.counter {
+ PacketFrameCounter::Frame { index } => {
+ if index == rx.count && index < 32 {
+ let start = 25 * index;
+ rx.packet[start..(start + 25)].copy_from_slice(&packet.payload);
+ rx.count += 1;
+ } else {
+ // unexpected order - something has gone wrong
+ self.state = State::Idle;
+ }
+ }
+ PacketFrameCounter::FinalFrame { payload_len } => {
+ let start = 25 * rx.count;
+ let end = start + payload_len;
+ rx.packet[start..(start + payload_len)]
+ .copy_from_slice(&packet.payload);
+ // TODO: compatible packets should be sent on port 0 too
+ let kiss =
+ KissFrame::new_full_packet(&rx.lsf.0, &rx.packet[0..end])
+ .unwrap();
+ self.kiss_to_host(kiss);
+ self.state = State::Idle;
+ }
+ }
+ }
+ _ => {
+ // Invalid transition
+ self.state = State::Idle;
+ }
+ }
+ }
+ Frame::Stream(stream) => {
+ match &mut self.state {
+ State::RxStream(ref mut rx) => {
+ // TODO: consider wraparound from 0x7fff
+ if stream.frame_number < rx.index {
+ let mut lich = LichCollection::new();
+ lich.set_segment(stream.lich_idx, stream.lich_part);
+ self.state = State::RxAcquiringStream(RxAcquiringStreamState { lich });
+ } else {
+ rx.index = stream.frame_number + 1;
+ let kiss = KissFrame::new_stream_data(&stream).unwrap();
+ self.kiss_to_host(kiss);
+ // TODO: end stream if LICH updates indicate non-META part has changed
+ // (this implies a new station)
+ if stream.end_of_stream {
+ self.state = State::Idle;
+ }
+ }
+ }
+ State::RxAcquiringStream(ref mut rx) => {
+ rx.lich.set_segment(stream.lich_idx, stream.lich_part);
+ if let Some(maybe_lsf) = rx.lich.try_assemble() {
+ let lsf = LsfFrame(maybe_lsf);
+ // LICH can change mid-transmission so wait until the CRC is correct
+ // to ensure (to high probability) we haven't done a "torn read"
+ if lsf.check_crc() == 0 {
+ let kiss = KissFrame::new_stream_setup(&lsf.0).unwrap();
+ self.kiss_to_host(kiss);
+ // TODO: avoid discarding the first data payload here
+ // need a queue depth of 2 for outgoing kiss
+ self.state = State::RxStream(RxStreamState {
+ lsf,
+ index: stream.frame_number + 1,
+ });
+ }
+ }
+ }
+ _ => {
+ // If coming from another state, we have missed something.
+ // Never mind, let's start tracking LICH.
+ let mut lich = LichCollection::new();
+ lich.set_segment(stream.lich_idx, stream.lich_part);
+ self.state = State::RxAcquiringStream(RxAcquiringStreamState { lich })
+ }
+ }
+ }
+ }
}
- /// Update the number of samples that have been received by the incoming stream, as a form of timekeeping
- pub fn advance_samples(&mut self, _samples: u64) {}
+ pub fn set_data_carrier_detect(&mut self, dcd: bool) {
+ self.dcd = dcd;
+ }
- pub fn set_data_carrier_detect(&mut self, _dcd: bool) {}
+ pub fn set_now(&mut self, now_samples: u64) {
+ self.now = now_samples;
+ match self.state {
+ State::TxEndingAtTime(time) => {
+ if now_samples >= time {
+ self.ptt = false;
+ self.state = State::Idle;
+ }
+ }
+ _ => (),
+ }
+ }
+
+ pub fn ptt(&self) -> bool {
+ self.ptt
+ }
- pub fn read_tx_frame(&mut self) -> Result<Option<Frame>, SoftTncError> {
- // yes we want to deal with Frames here
- // it's important to establish successful decode that SoftDemodulator is aware of the frame innards
- Ok(None)
+ pub fn set_tx_end_time(&mut self, in_samples: usize) {
+ match self.state {
+ State::TxEnding => {
+ self.state = State::TxEndingAtTime(self.now + in_samples as u64);
+ }
+ _ => (),
+ }
+ }
+
+ pub fn read_tx_frame(&mut self) -> Option<ModulatorFrame> {
+ match self.state {
+ State::Idle | State::RxAcquiringStream(_) | State::RxStream(_) | State::RxPacket(_) => {
+ // We will let CSMA decide whether to actually go ahead.
+ // That's not implemented yet, so let's just check DCD.
+ let channel_free = !self.dcd;
+ let stream_wants_to_tx = self.stream_pending_lsf.is_some();
+ let packet_wants_to_tx = self.packet_full || (self.packet_next != self.packet_curr);
+ if channel_free && stream_wants_to_tx {
+ self.state = State::TxStream;
+ } else if channel_free && packet_wants_to_tx {
+ self.state = State::TxPacket;
+ } else {
+ return None;
+ }
+ self.ptt = true;
+ // TODO: true txdelay
+ Some(ModulatorFrame::Preamble { tx_delay: 0 })
+ }
+ State::TxStream => {
+ if !self.stream_full && self.stream_next == self.stream_curr {
+ return None;
+ }
+ if let Some(lsf) = self.stream_pending_lsf.take() {
+ return Some(ModulatorFrame::Lsf(lsf));
+ }
+ let frame = self.stream_queue[self.stream_curr].clone();
+ if self.stream_full {
+ self.stream_full = false;
+ }
+ self.stream_curr = (self.stream_curr + 1) % 8;
+ if frame.end_of_stream {
+ self.state = State::Idle;
+ }
+ Some(ModulatorFrame::Stream(frame))
+ }
+ State::TxStreamSentEndOfStream => {
+ self.state = State::TxEnding;
+ Some(ModulatorFrame::EndOfTransmission)
+ }
+ State::TxPacket => {
+ if !self.packet_full && self.packet_next == self.packet_curr {
+ return None;
+ }
+ while self.packet_next != self.packet_curr {
+ match self.packet_queue[self.packet_curr].next_frame() {
+ Some(frame) => {
+ return Some(frame);
+ }
+ None => {
+ self.packet_curr = (self.packet_curr + 1) % 4;
+ }
+ }
+ }
+ self.state = State::TxEnding;
+ Some(ModulatorFrame::EndOfTransmission)
+ }
+ State::TxEnding | State::TxEndingAtTime(_) => {
+ // Once we have signalled EOT we withold any new frames until
+ // the channel fully clears and we are ready to TX again
+ None
+ }
+ }
}
/// Read KISS message to be sent to host.
///
/// After each frame input, this should be consumed in a loop until length 0 is returned.
/// This component will never block. Upstream interface can provide blocking `read()` if desired.
- pub fn read_kiss(&mut self, target_buf: &mut [u8]) -> Result<usize, SoftTncError> {
+ pub fn read_kiss(&mut self, target_buf: &mut [u8]) -> usize {
match self.outgoing_kiss.as_mut() {
Some(outgoing) => {
let n = (outgoing.kiss_frame.len - outgoing.sent).min(target_buf.len());
target_buf[0..n]
.copy_from_slice(&outgoing.kiss_frame.data[outgoing.sent..(outgoing.sent + n)]);
outgoing.sent += n;
- Ok(n)
+ if outgoing.sent == outgoing.kiss_frame.len {
+ self.outgoing_kiss = None;
+ }
+ n
}
- None => Ok(0),
+ None => 0,
}
}
- pub fn write_kiss(&mut self, buf: &[u8]) -> Result<usize, SoftTncError> {
+ /// Host sends in some KISS data.
+ pub fn write_kiss(&mut self, buf: &[u8]) -> usize {
let target_buf = self.kiss_buffer.buf_remaining();
let n = buf.len().min(target_buf.len());
target_buf[0..n].copy_from_slice(&buf[0..n]);
self.kiss_buffer.did_write(n);
- while let Some(_kiss_frame) = self.kiss_buffer.next_frame() {
- // TODO: handle host-to-TNC message
+ while let Some(kiss_frame) = self.kiss_buffer.next_frame() {
+ let Ok(port) = kiss_frame.port() else {
+ continue;
+ };
+ if port == PORT_PACKET_BASIC {
+ } else if port == PORT_PACKET_FULL {
+ } else if port == PORT_STREAM {
+ }
}
- Ok(n)
+ n
+ }
+
+ fn kiss_to_host(&mut self, kiss_frame: KissFrame) {
+ self.outgoing_kiss = Some(OutgoingKiss {
+ kiss_frame,
+ sent: 0,
+ });
}
}
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq, Clone)]
pub enum SoftTncError {
General(&'static str),
+ InvalidState,
}
struct OutgoingKiss {
}
enum State {
- /// Nothing happening.
+ /// Nothing happening. We may have TX data queued but we won't act on it until CSMA opens up.
Idle,
/// We received some stream data but missed the leading LSF so we are trying to assemble from LICH.
/// We are receiving a packet. All is well so far, and there is more data to come before we tell the host.
RxPacket(RxPacketState),
- // TODO: TX
+
+ /// PTT is on and this is a stream-type transmission. New data may be added.
+ TxStream,
+
+ /// We have delivered the last frame in the current stream
+ TxStreamSentEndOfStream,
+
+ /// PTT is on and this is a packet-type transmission. New packets may be enqueued.
+ TxPacket,
+
+ /// We gave modulator an EndOfTransmission. PTT is still on, waiting for modulator to advise end time.
+ TxEnding,
+
+ /// Ending transmission, PTT remains on, but we know the timestamp at which we should disengage it.
+ TxEndingAtTime(u64),
}
struct RxAcquiringStreamState {
struct RxStreamState {
/// Track identifying information for this transmission so we can tell if it changes.
lsf: LsfFrame,
+
+ /// Expected next frame number. Allowed to skip values on RX, but not go backwards.
+ index: u16,
}
struct RxPacketState {
+ /// Initial LSF
+ lsf: LsfFrame,
+
/// Accumulation of packet data that we have received so far.
packet: [u8; 825],
- /// Number of frames we have received. If we are stably in the RxPacket state,
- /// this will be between 1 and 32 inclusive. The first frame gets us into the
- /// rx state, and the maximum 33rd frame must end the transmission and state.
+ /// Number of payload frames we have received. If we are stably in the RxPacket state,
+ /// this will be between 0 and 32 inclusive.
count: usize,
}
+
+struct PendingPacket {
+ lsf: Option<LsfFrame>,
+
+ app_data: [u8; 825],
+ app_data_len: usize,
+ app_data_transmitted: usize,
+}
+
+impl PendingPacket {
+ /// Returns next frame, not including preamble or EOT.
+ ///
+ /// False means all data frames have been sent.
+ fn next_frame(&mut self) -> Option<ModulatorFrame> {
+ if let Some(lsf) = self.lsf.take() {
+ return Some(ModulatorFrame::Lsf(lsf));
+ }
+ if self.app_data_len == self.app_data_transmitted {
+ return None;
+ }
+ let remaining = self.app_data_len - self.app_data_transmitted;
+ let (counter, data_len) = if remaining <= 25 {
+ (
+ PacketFrameCounter::FinalFrame {
+ payload_len: remaining,
+ },
+ remaining,
+ )
+ } else {
+ (
+ PacketFrameCounter::Frame {
+ index: self.app_data_transmitted / 25,
+ },
+ 25,
+ )
+ };
+ let mut payload = [0u8; 25];
+ payload.copy_from_slice(
+ &self.app_data[self.app_data_transmitted..(self.app_data_transmitted + data_len)],
+ );
+ self.app_data_transmitted += data_len;
+ Some(ModulatorFrame::Packet(PacketFrame { payload, counter }))
+ }
+}
+
+impl Default for PendingPacket {
+ fn default() -> Self {
+ Self {
+ lsf: None,
+ app_data: [0u8; 825],
+ app_data_len: 0,
+ app_data_transmitted: 0,
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use crate::kiss::{KissCommand, PORT_STREAM};
+ use crate::protocol::StreamFrame;
+
+ // TODO: finish all handle_frame tests as below
+ // this will be much more straightforward when we have a way to create LSFs programatically
+
+ // receiving a single-frame packet
+
+ // receiving a multi-frame packet
+
+ // part of one packet and then another
+
+ #[test]
+ fn tnc_receive_stream() {
+ let lsf = LsfFrame([
+ 255, 255, 255, 255, 255, 255, 0, 0, 0, 159, 221, 81, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 131, 53,
+ ]);
+ let stream1 = StreamFrame {
+ lich_idx: 0,
+ lich_part: [255, 255, 255, 255, 255],
+ frame_number: 0,
+ end_of_stream: false,
+ stream_data: [
+ 128, 0, 119, 115, 220, 252, 41, 235, 8, 0, 116, 195, 94, 244, 45, 75,
+ ],
+ };
+ let stream2 = StreamFrame {
+ lich_idx: 1,
+ lich_part: [255, 0, 0, 0, 159],
+ frame_number: 1,
+ end_of_stream: true,
+ stream_data: [
+ 17, 0, 94, 82, 216, 135, 181, 15, 30, 0, 125, 195, 152, 183, 41, 57,
+ ],
+ };
+ let mut tnc = SoftTnc::new();
+ let mut kiss = KissFrame::new_empty();
+ assert_eq!(tnc.read_kiss(&mut kiss.data), 0);
+
+ tnc.handle_frame(Frame::Lsf(lsf));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let mut payload_buf = [0u8; 2048];
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 30);
+
+ tnc.handle_frame(Frame::Stream(stream1));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 26);
+
+ tnc.handle_frame(Frame::Stream(stream2));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 26);
+ }
+
+ #[test]
+ fn tnc_acquire_stream() {
+ let frames = [
+ StreamFrame {
+ lich_idx: 0,
+ lich_part: [255, 255, 255, 255, 255],
+ frame_number: 0,
+ end_of_stream: false,
+ stream_data: [
+ 128, 0, 119, 115, 220, 252, 41, 235, 8, 0, 116, 195, 94, 244, 45, 75,
+ ],
+ },
+ StreamFrame {
+ lich_idx: 1,
+ lich_part: [255, 0, 0, 0, 159],
+ frame_number: 1,
+ end_of_stream: false,
+ stream_data: [
+ 17, 0, 94, 82, 216, 135, 181, 15, 30, 0, 125, 195, 152, 183, 41, 57,
+ ],
+ },
+ StreamFrame {
+ lich_idx: 2,
+ lich_part: [221, 81, 5, 5, 0],
+ frame_number: 2,
+ end_of_stream: false,
+ stream_data: [
+ 17, 128, 93, 74, 154, 167, 169, 11, 20, 0, 116, 91, 158, 220, 45, 111,
+ ],
+ },
+ StreamFrame {
+ lich_idx: 3,
+ lich_part: [0, 0, 0, 0, 0],
+ frame_number: 3,
+ end_of_stream: false,
+ stream_data: [
+ 15, 128, 114, 83, 218, 252, 59, 111, 31, 128, 116, 91, 84, 231, 45, 105,
+ ],
+ },
+ StreamFrame {
+ lich_idx: 4,
+ lich_part: [0, 0, 0, 0, 0],
+ frame_number: 4,
+ end_of_stream: false,
+ stream_data: [
+ 9, 128, 119, 115, 220, 220, 57, 15, 48, 128, 124, 83, 158, 236, 181, 91,
+ ],
+ },
+ StreamFrame {
+ lich_idx: 5,
+ lich_part: [0, 0, 0, 131, 53],
+ frame_number: 5,
+ end_of_stream: false,
+ stream_data: [
+ 52, 0, 116, 90, 152, 167, 225, 216, 32, 0, 116, 83, 156, 212, 33, 216,
+ ],
+ },
+ ];
+
+ let mut tnc = SoftTnc::new();
+ let mut kiss = KissFrame::new_empty();
+ for f in frames {
+ tnc.handle_frame(Frame::Stream(f));
+ }
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ let mut payload_buf = [0u8; 2048];
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 30);
+ assert_eq!(
+ &payload_buf[0..30],
+ [
+ 255, 255, 255, 255, 255, 255, 0, 0, 0, 159, 221, 81, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 131, 53,
+ ]
+ );
+ }
+
+ #[test]
+ fn tnc_handle_skipped_stream_frame() {
+ let lsf = LsfFrame([
+ 255, 255, 255, 255, 255, 255, 0, 0, 0, 159, 221, 81, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 131, 53,
+ ]);
+ let stream1 = StreamFrame {
+ lich_idx: 0,
+ lich_part: [255, 255, 255, 255, 255],
+ frame_number: 0,
+ end_of_stream: false,
+ stream_data: [
+ 128, 0, 119, 115, 220, 252, 41, 235, 8, 0, 116, 195, 94, 244, 45, 75,
+ ],
+ };
+ let stream3 = StreamFrame {
+ lich_idx: 2,
+ lich_part: [221, 81, 5, 5, 0],
+ frame_number: 2,
+ end_of_stream: false,
+ stream_data: [
+ 17, 128, 93, 74, 154, 167, 169, 11, 20, 0, 116, 91, 158, 220, 45, 111,
+ ],
+ };
+ let mut tnc = SoftTnc::new();
+ let mut kiss = KissFrame::new_empty();
+ assert_eq!(tnc.read_kiss(&mut kiss.data), 0);
+
+ tnc.handle_frame(Frame::Lsf(lsf));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let mut payload_buf = [0u8; 2048];
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 30);
+
+ tnc.handle_frame(Frame::Stream(stream1));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 26);
+
+ tnc.handle_frame(Frame::Stream(stream3));
+ kiss.len = tnc.read_kiss(&mut kiss.data);
+ assert_eq!(kiss.command().unwrap(), KissCommand::DataFrame);
+ assert_eq!(kiss.port().unwrap(), PORT_STREAM);
+
+ let n = kiss.decode_payload(&mut payload_buf).unwrap();
+ assert_eq!(n, 26);
+ }
+}
projects / m17rt / blobdiff