Merge branch 'ebus-rust'HEADmaster

1 files changed, 263 insertions, 0 deletions

diff --git a/ebus-rust/src/layer2/mod.rs b/ebus-rust/src/layer2/mod.rs
new file mode 100644
index 0000000..ef07aad
--- /dev/null
+++ b/ebus-rust/src/layer2/mod.rs
@@ -0,0 +1,263 @@
+use std::fmt;
+
+mod crc;
+
+const EBUS_SYN: u8 = 0xaa;
+const EBUS_ESCAPE: u8 = 0xa9;
+const EBUS_ACKOK: u8 = 0x00;
+
+#[derive(Default)]
+pub struct Packet {
+    pub source: u8,
+    pub destination: u8,
+    pub primary: u8,
+    pub secondary: u8,
+    payload_length: u8,
+    payload: Vec<u8>,
+    pub crc: u8,
+    payload_slave_length: u8,
+    payload_slave: Vec<u8>,
+    crc_slave: u8,
+}
+
+impl Packet {
+    // payload returns the un-escaped payload
+    pub fn payload_decoded(&self) -> Vec<u8> {
+        let mut v = Vec::new();
+        let mut i = 0;
+
+        while i < self.payload.len() {
+            let c = self.payload[i];
+            if c == EBUS_ESCAPE && i + 1 < self.payload.len() {
+                i += 1;
+                let c = self.payload[i];
+                if c == 0x0 {
+                    v.push(EBUS_ESCAPE);
+                } else if c == 0x1 {
+                    v.push(EBUS_SYN);
+                } else {
+                    v.push(c);
+                }
+            } else {
+                v.push(c);
+            }
+            i += 1;
+        }
+        v
+    }
+
+    pub fn calc_crc(&self) -> u8 {
+        let x = &[
+            self.source,
+            self.destination,
+            self.primary,
+            self.secondary,
+            self.payload_length,
+        ];
+        crc::crc(&[&x[..], self.payload.as_slice()].concat())
+    }
+}
+
+impl fmt::Debug for Packet {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.payload_slave_length > 0 {
+            f.debug_struct("Packet")
+                .field("source", &format!("{:#02x}", &self.source))
+                .field("destination", &format!("{:#02x}", &self.destination))
+                .field("primary", &format!("{:#02x}", &self.primary))
+                .field("secondary", &format!("{:#02x}", &self.secondary))
+                .field("payload", &format!("{:02x?}", &self.payload))
+                .field("payload_length", &self.payload_length)
+                .field("crc", &format!("{:#02x}", &self.crc))
+                .field(
+                    "payload_slave_length",
+                    &format!("{:#02x}", &self.payload_slave_length),
+                )
+                .field("payload_slave", &format!("{:02x?}", &self.payload_slave))
+                .field("crc_slave", &format!("{:#02x}", &self.crc_slave))
+                .finish()
+        } else {
+            f.debug_struct("Packet")
+                .field("source", &format!("{:#02x}", &self.source))
+                .field("destination", &format!("{:#02x}", &self.destination))
+                .field("primary", &format!("{:#02x}", &self.primary))
+                .field("secondary", &format!("{:#02x}", &self.secondary))
+                .field("payload", &format!("{:02x?}", &self.payload))
+                .field("payload_length", &self.payload_length)
+                .field("crc", &format!("{:#02x}", &self.crc))
+                .finish()
+        }
+    }
+}
+
+fn read_header(data: &[u8]) -> nom::IResult<&[u8], Packet> {
+    use nom::number::streaming::u8;
+    use nom::sequence::tuple;
+    let (input, (source, destination, primary, secondary, payload_length)) =
+        tuple((u8, u8, u8, u8, u8))(data)?;
+    Ok((
+        input,
+        Packet {
+            source,
+            destination,
+            primary,
+            secondary,
+            payload_length,
+            ..Default::default()
+        },
+    ))
+}
+
+fn read_packet(data: &[u8]) -> nom::IResult<&[u8], Packet> {
+    use nom::bytes::streaming::tag;
+    use nom::combinator::opt;
+    use nom::multi::count;
+    use nom::number::streaming::u8;
+    use nom::sequence::tuple;
+
+    let (input, mut packet) = read_header(data)?;
+
+    let (input2, (payload, crc, _, payload_slave_length)) = tuple((
+        count(u8, packet.payload_length as usize), // payload
+        u8,                                        // crc
+        opt(tag([EBUS_ACKOK])),                    // ACK but non-ack is tolerated
+        u8,                                        // SYN or payload slave length
+    ))(input)?;
+    packet.payload = payload;
+    packet.crc = crc;
+
+    if payload_slave_length != EBUS_SYN {
+        packet.payload_slave_length = payload_slave_length;
+        let (input3, (payload_slave, crc_slave)) =
+            tuple((count(u8, payload_slave_length as usize), u8))(input2)?;
+        packet.payload_slave = payload_slave;
+        packet.crc_slave = crc_slave;
+        Ok((input3, packet))
+    } else {
+        Ok((input2, packet))
+    }
+}
+
+pub fn parse(data: &[u8]) -> Result<Packet, nom::Err<nom::error::Error<&[u8]>>> {
+    use nom::bytes::streaming::take_while;
+    use nom::sequence::preceded;
+    fn take_syn(data: &[u8]) -> nom::IResult<&[u8], &[u8]> {
+        take_while(|chr| chr == EBUS_SYN)(data)
+    }
+
+    let mut parser = preceded(take_syn, read_packet);
+    let result = parser(data);
+    result.map(|r| r.1)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn teststructure_mastermaster() {
+        let data: Vec<u8> = vec![
+            170, // Syn
+            170, // Syn
+            003, // Source
+            241, // Destination
+            008, // primaryCommand
+            000, // secondaryCommand
+            008, // payloadLength
+            128, // p1
+            040, // p2
+            230, // p3
+            002, // p4
+            000, // p5
+            002, // p6
+            000, // p7
+            010, // p8
+            128, // CRC
+            000, // ACK
+            170, // SYN
+            170,
+        ];
+
+        let res = parse(&data).unwrap();
+        assert_eq!(res.source, 0003);
+        assert_eq!(res.destination, 241);
+        assert_eq!(res.primary, 008);
+        assert_eq!(res.secondary, 000);
+        assert_eq!(res.payload_length, 0008);
+        assert_eq!(res.crc, 128);
+        assert_eq!(res.payload, vec![128, 040, 230, 002, 000, 002, 000, 010]);
+    }
+
+    #[test]
+    fn testcrc() {
+        let packets = [
+            &[
+                0x10, 0x03, 0x08, 0x00, 0x08, 0x00, 0x05, 0x00, 0x13, 0x80, 0x40, 0x00, 0x0a, 0x71,
+                0x00, 0xaa,
+            ][..],
+            &[
+                0x03, 0xf1, 0x08, 0x00, 0x08, 0x00, 0x14, 0x00, 0x13, 0x80, 0x00, 0x00, 0x0f, 0xc7,
+                0x00, 0xaa,
+            ][..],
+            &[
+                0x10, 0x03, 0x05, 0x07, 0x09, 0x00, 0x01, 0x50, 0x00, 0x01, 0x00, 0xff, 0x14, 0xff,
+                0xa6, 0x00, 0xaa,
+            ][..],
+            &[
+                0xf1, 0xfe, 0x05, 0x03, 0x08, 0x01, 0x00, 0x40, 0xff, 0x30, 0xff, 0x00, 0x13, 0xd8,
+                0x00, 0xaa,
+            ][..],
+            &[
+                0x03, 0xfe, 0x05, 0x03, 0x08, 0x01, 0x00, 0x00, 0x00, 0x30, 0x17, 0x33, 0x13, 0x82,
+                0x00, 0xaa,
+            ][..],
+            &[
+                // 00000d60: aaaa 1003 0507 09bb 044b 0300 80ff 54ff  .........K....T.
+                // 00000d70: 0400 aaaa aaaa aaaa f1fe 0503 0801 0110  ................
+                0x10, 0x03, 0x05, 0x07, 0x09, 0xbb, 0x04, 0x4b, 0x03, 0x00, 0x80, 0xff, 0x54, 0xff,
+                0x04, 0x00, 0xaa,
+            ][..],
+        ];
+        for d in &packets {
+            let p = parse(d).unwrap();
+            assert_eq!(p.crc, p.calc_crc(), "{:?}", p);
+        }
+    }
+
+    #[test]
+    fn test_escape() {
+        let data: Vec<u8> = vec![
+            170,         // Syn
+            170,         // Syn
+            3,           // Source
+            241,         // Destination
+            8,           // primaryCommand
+            0,           // secondaryCommand
+            8,           // payloadLength
+            128,         // p1
+            40,          // p2
+            EBUS_ESCAPE, // p3
+            1,           // p4
+            EBUS_ESCAPE, // p5
+            0,           // p6
+            0,           // p7
+            10,          // p8
+            128,         // CRC
+            0,           // ACK
+            170,         // SYN
+            170,
+        ];
+
+        let res = parse(&data).unwrap();
+        assert_eq!(res.source, 0003);
+        assert_eq!(res.destination, 241);
+        assert_eq!(res.primary, 008);
+        assert_eq!(res.secondary, 000);
+        assert_eq!(res.payload_length, 0008);
+        assert_eq!(res.crc, 128);
+        assert_eq!(
+            res.payload_decoded(),
+            vec![128, 040, EBUS_SYN, EBUS_ESCAPE, 000, 010]
+        );
+    }
+}