refactor: move firmware workspace under firmware

firmware/libs/kaptan-mavlink/src/commands/arm.rs

@@ -0,0 +1,102 @@
+//! Narrow MAVLink arm/disarm command decoding.
+//!
+//! This module deliberately accepts no actuator-value or motor-test command.
+//! A board must pass accepted requests to its single actuator-state owner; this
+//! decoder has no access to output hardware.
+
+use mavlink::Message;
+
+use crate::{MavlinkFrame, message};
+
+/// A requested change to the vehicle's arming state.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum ArmRequest {
+    /// Request the armed-idle state.
+    Arm,
+    /// Request electrically inactive outputs.
+    Disarm,
+}
+
+/// Decodes a targeted MAVLink `MAV_CMD_COMPONENT_ARM_DISARM` command.
+///
+/// Only `param1` values exactly equal to `0.0` (disarm) or `1.0` (arm) are
+/// accepted. Broadcast targets are intentionally rejected: an actuator command
+/// must name this vehicle and its component explicitly.
+pub fn decode_arm_request(
+    frame: &MavlinkFrame,
+    system_id: u8,
+    component_id: u8,
+) -> Option<ArmRequest> {
+    let message = message::MavMessage::parse(
+        mavlink::MavlinkVersion::V2,
+        frame.message_id(),
+        frame.payload(),
+    )
+    .ok()?;
+
+    let message::MavMessage::COMMAND_LONG(command) = message else {
+        return None;
+    };
+    if command.command != message::MavCmd::MAV_CMD_COMPONENT_ARM_DISARM
+        || command.target_system != system_id
+        || command.target_component != component_id
+    {
+        return None;
+    }
+
+    match command.param1 {
+        0.0 => Some(ArmRequest::Disarm),
+        1.0 => Some(ArmRequest::Arm),
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{ArmRequest, decode_arm_request};
+    use crate::{MavlinkFrame, message};
+
+    fn command(target_system: u8, target_component: u8, value: f32) -> MavlinkFrame {
+        let mut frame = MavlinkFrame::new();
+        frame.serialize_message_data(
+            message::MavHeader {
+                sequence: 0,
+                system_id: 42,
+                component_id: 7,
+            },
+            &message::COMMAND_LONG_DATA {
+                param1: value,
+                param2: 0.0,
+                param3: 0.0,
+                param4: 0.0,
+                param5: 0.0,
+                param6: 0.0,
+                param7: 0.0,
+                command: message::MavCmd::MAV_CMD_COMPONENT_ARM_DISARM,
+                target_system,
+                target_component,
+                confirmation: 0,
+            },
+        );
+        frame
+    }
+
+    #[test]
+    fn accepts_explicit_targeted_arm_and_disarm() {
+        assert_eq!(
+            decode_arm_request(&command(1, 1, 1.0), 1, 1),
+            Some(ArmRequest::Arm)
+        );
+        assert_eq!(
+            decode_arm_request(&command(1, 1, 0.0), 1, 1),
+            Some(ArmRequest::Disarm)
+        );
+    }
+
+    #[test]
+    fn rejects_broadcast_wrong_target_and_invalid_parameter() {
+        assert_eq!(decode_arm_request(&command(0, 0, 1.0), 1, 1), None);
+        assert_eq!(decode_arm_request(&command(2, 1, 1.0), 1, 1), None);
+        assert_eq!(decode_arm_request(&command(1, 1, 0.5), 1, 1), None);
+    }
+}