swaits
4cccb65124
The wire protocol is re-specified as DongLoRa Protocol v2 (see PROTOCOL.md). Every type_id, tag-correlation rule, and field layout is incompatible with 0.1.0. * Add PROTOCOL.md as the normative spec for the v2 wire format. * Replace framing.rs with a streaming FrameDecoder that emits (type_id, tag, payload) triples on each COBS-delimited, CRC-checked frame. * Split the single-file lib.rs into dedicated modules: frame, commands, events, errors, modulation, info, crc, chip_id. Re-exports preserve convenience imports at the crate root. * Replace RadioConfig / Bandwidth with a Modulation enum covering LoRa, FSK/GFSK, LR-FHSS, and FLRC, each with its own typed parameter struct. * Add TxFlags, RxOrigin, SetConfigResult, OkPayload to model v2 response shapes, and RadioChipId for GET_INFO. * Rewrite fuzz corpus: replace the 4 cobs_* / command_roundtrip targets with decoder_feed, frame_roundtrip, lora_config_roundtrip, and parse_device_message; drop parse_radio_config. * Expand proptest and mutation-killer coverage for the new wire shape. * Rewrite canonical-byte test vectors against the v2 spec.
58 lines
1.8 KiB
Rust
58 lines
1.8 KiB
Rust
//! CRC-16/CCITT-FALSE — the wire-level integrity check used by DongLoRa Protocol.
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//!
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//! Polynomial `0x1021`, initial value `0xFFFF`, no reflection, XOR-out `0x0000`.
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//! This is the same variant also known as CRC-16/AUTOSAR or
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//! CRC-16/IBM-3740. It is **NOT** the same as CRC-16/KERMIT,
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//! CRC-16/XMODEM, or plain "CRC-16/CCITT" — those use different initial
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//! values or reflect their inputs.
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//!
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//! Check value: `crc16("123456789") == 0x29B1`. A module-level test pins
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//! this, and `tests/vectors.rs` anchors every Appendix C wire example.
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/// CRC-16/CCITT-FALSE of `data`.
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pub fn crc16(data: &[u8]) -> u16 {
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let mut crc: u16 = 0xFFFF;
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for &byte in data {
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crc ^= (byte as u16) << 8;
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for _ in 0..8 {
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if crc & 0x8000 != 0 {
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crc = (crc << 1) ^ 0x1021;
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} else {
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crc <<= 1;
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}
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}
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}
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crc
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn check_value_matches_spec() {
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// PROTOCOL.md §2.2: CRC-16/CCITT-FALSE of ASCII "123456789" is 0x29B1.
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assert_eq!(crc16(b"123456789"), 0x29B1);
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}
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#[test]
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fn empty_input_is_initial_value() {
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// No reflection, no XOR-out: empty input leaves the init value untouched.
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assert_eq!(crc16(&[]), 0xFFFF);
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}
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#[test]
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fn single_zero_byte() {
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// 0xFFFF XOR 0x0000 = 0xFFFF, then 8 shift-and-maybe-xor rounds.
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// Worked out by hand against the reference impl in Appendix B.
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assert_eq!(crc16(&[0x00]), 0xE1F0);
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}
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#[test]
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fn differs_from_kermit_variant() {
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// CRC-16/KERMIT of "123456789" is 0x2189 — if we ever accidentally
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// swap init or reflection, this vector catches it.
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assert_ne!(crc16(b"123456789"), 0x2189);
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}
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}
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