From eb5befa55ca0ba46bf8de99393c7acb3eda03e96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20K=C3=A4nner?= <max.kaenner@gmail.com>
Date: Tue, 30 Jan 2024 20:15:03 +0100
Subject: [PATCH] A start

---
 Cargo.toml |  12 +++--
 README.md  |   4 +-
 src/lib.rs | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 8cfc59a..68e7af4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,10 +1,13 @@
 [package]
-name = "lib-rs"
+name = "crsf-rs"
 version = "0.1.0"
 edition = "2021"
-description = "library template"
-license_file = "MIT OR Apache-2.0"
+description = "This crate provides a #[no_std] parser for the crossfire protocol"
+license = "MIT OR Apache-2.0"
 repository = "https://git.mkaenner.de/max/lib-rs"
+keywords = ["crsf", "crossfire"]
+categories = ["embedded"]
+authors = ["Max Känner <max.kaenner@gmail.com>"]
 
 [lints.rust]
 unsafe_code = "forbid"
@@ -19,3 +22,6 @@ cargo = "warn"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+num_enum = { version = "=0.5", default-features = false }
+bitfield = { version = "=0.13" }
+heapless = { version = "=0.7" }
diff --git a/README.md b/README.md
index cfbac2a..97794c6 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,3 @@
-# lib-rs
+# crsf-rs
 
-Template for rust libraries
\ No newline at end of file
+A library for decoding crossfire packages. This library is fully #[no_std] compatible
diff --git a/src/lib.rs b/src/lib.rs
index 139597f..56d8576 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,2 +1,131 @@
+#![cfg_attr(not(test), no_std)]
 
+use bitfield::bitfield;
+use heapless::HistoryBuffer;
+use num_enum::{IntoPrimitive, TryFromPrimitive, TryFromPrimitiveError};
 
+#[derive(Debug, PartialEq, Eq, Clone, Copy, IntoPrimitive, TryFromPrimitive)]
+#[repr(u8)]
+pub enum FrameType {
+    Gps = 0x02,
+    Vario = 0x07,
+    BatterySensor = 0x08,
+    BaroAltitude = 0x09,
+    LinkStatistics = 0x14,
+    OpenTxSync = 0x10,
+    RadioId = 0x3A,
+    RcChannelsPacked = 0x16,
+    Attitude = 0x1E,
+    FlightMode = 0x21,
+    // Extended Header Frames
+    DevicePing = 0x28,
+    DeviceInfo = 0x29,
+    ParameterSettingsEntry = 0x2B,
+    ParameterRead = 0x2C,
+    ParameterWrite = 0x2D,
+    ELRSStatus = 0x2E,
+    Command = 0x32,
+    // KISS frames
+    KissReq = 0x78,
+    KissResp = 0x79,
+    // MSP commands
+    MspReq = 0x7A,
+    MspResp = 0x7B,
+    MspWrite = 0x7C,
+    // Ardupilot frames
+    ArdupilotResp = 0x80,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, IntoPrimitive, TryFromPrimitive)]
+#[repr(u8)]
+pub enum Address {
+    Broadcast = 0x00,
+    Usb = 0x10,
+    TbsCorePnpPro = 0x80,
+    Reserved1 = 0x8A,
+    CurrentSensor = 0xC0,
+    Gps = 0xC2,
+    TbsBlackbox = 0xC4,
+    FlightController = 0xC8,
+    Reserved2 = 0xCA,
+    RaceTag = 0xCC,
+    RadioTransmitter = 0xEA,
+    CrsfReceiver = 0xEC,
+    CrsfTrasmitter = 0xEE,
+    ElrsLua = 0xEF,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+struct Header {
+    address: Address,
+    size: u8,
+    frame_type: FrameType,
+}
+
+impl Header {
+    fn try_from_bytes(bytes: [u8; 3]) -> Result<Self, u8> {
+        Ok(Self {
+            address: bytes[0]
+                .try_into()
+                .map_err(|TryFromPrimitiveError { number }| number)?,
+            size: bytes[1],
+            frame_type: bytes[2]
+                .try_into()
+                .map_err(|TryFromPrimitiveError { number }| number)?,
+        })
+    }
+}
+
+bitfield! {
+    struct RcChannels([u8]);
+    impl Debug;
+    u16;
+    ch1, set_ch1: Self::upper(1), Self::lower(1);
+    ch2, set_ch2: Self::upper(2), Self::lower(2);
+    ch3, set_ch3: Self::upper(3), Self::lower(3);
+    ch4, set_ch4: Self::upper(4), Self::lower(4);
+    ch5, set_ch5: Self::upper(5), Self::lower(5);
+    ch6, set_ch6: Self::upper(6), Self::lower(6);
+    ch7, set_ch7: Self::upper(7), Self::lower(7);
+    ch8, set_ch8: Self::upper(8), Self::lower(8);
+    ch9, set_ch9: Self::upper(9), Self::lower(9);
+    ch10, set_ch10: Self::upper(10), Self::lower(10);
+    ch11, set_ch11: Self::upper(11), Self::lower(11);
+    ch12, set_ch12: Self::upper(12), Self::lower(12);
+    ch13, set_ch13: Self::upper(13), Self::lower(13);
+    ch14, set_ch14: Self::upper(14), Self::lower(14);
+    ch15, set_ch15: Self::upper(15), Self::lower(15);
+    ch16, set_ch16: Self::upper(16), Self::lower(16);
+}
+
+impl<T> RcChannels<T> {
+    const BITS_PER_CHANNEL: usize = 11;
+
+    const fn upper(ch: usize) -> usize {
+        Self::lower(ch) + Self::BITS_PER_CHANNEL - 1
+    }
+
+    const fn lower(ch: usize) -> usize {
+        Self::BITS_PER_CHANNEL * (ch - 1)
+    }
+}
+
+pub struct CrsfParser {
+    buffer: HistoryBuffer<u8, { Self::MAX_PACKET_SIZE }>,
+}
+
+impl CrsfParser {
+    const MAX_PACKET_SIZE: usize = 64;
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn rc_channels() {
+        let input = [
+            0xc8, 0x18, 0x16, 0xe0, 0x3, 0x1f, 0xb3, 0xc0, 0xf7, 0xb, 0xee, 0x69, 0x8f, 0x15, 0xe0,
+            0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x78, 0xd9, 0xdb, 0xb4, 0xc8,
+        ];
+        unimplemented!();
+    }
+}