kaptan-actuator: improve config abstractions

Signed-off-by: Onur Özkan <work@onurozkan.dev>

libs/kaptan-actuator/src/pwm.rs

@@ -1,7 +1,56 @@
 //! Conventional PWM framing and arming policy.
 
+use crate::ArmingDuration;
 use core::sync::atomic::{AtomicBool, AtomicU16, Ordering};
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct Config {
+    frame_rate: Rate,
+    minimum_pulse: PulseWidth,
+    armed_idle_pulse: PulseWidth,
+    arming_duration: ArmingDuration,
+}
+
+impl Config {
+    pub const fn new(
+        frame_rate: Rate,
+        minimum_pulse: PulseWidth,
+        armed_idle_pulse: PulseWidth,
+        arming_duration: ArmingDuration,
+    ) -> Option<Self> {
+        match frame_rate.period_microseconds() {
+            Some(period)
+                if minimum_pulse.microseconds() <= armed_idle_pulse.microseconds()
+                    && armed_idle_pulse.microseconds() <= period =>
+            {
+                Some(Self {
+                    frame_rate,
+                    minimum_pulse,
+                    armed_idle_pulse,
+                    arming_duration,
+                })
+            }
+            _ => None,
+        }
+    }
+
+    pub const fn frame_rate(self) -> Rate {
+        self.frame_rate
+    }
+
+    pub const fn minimum_pulse(self) -> PulseWidth {
+        self.minimum_pulse
+    }
+
+    pub const fn armed_idle_pulse(self) -> PulseWidth {
+        self.armed_idle_pulse
+    }
+
+    pub const fn arming_duration(self) -> ArmingDuration {
+        self.arming_duration
+    }
+}
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct Rate(u16);
 
@@ -114,7 +163,8 @@ impl ArmSequence {
 
 #[cfg(test)]
 mod tests {
-    use super::{ArmSequence, FrameValue, PulseWidth, Rate};
+    use super::{ArmSequence, Config, FrameValue, PulseWidth, Rate};
+    use crate::ArmingDuration;
 
     #[test]
     fn rate_describes_an_exact_400_hertz_frame() {
@@ -134,4 +184,15 @@ mod tests {
         sequence.disarm();
         assert_eq!(sequence.next_frame(), None);
     }
+
+    #[test]
+    fn requires_an_exact_frame_and_ordered_pulses() {
+        let duration = ArmingDuration::from_millis(2_000).unwrap();
+        let rate = Rate::new(400).unwrap();
+        let minimum = PulseWidth::new(1_000).unwrap();
+        let idle = PulseWidth::new(1_100).unwrap();
+        assert!(Config::new(rate, minimum, idle, duration).is_some());
+        assert!(Config::new(Rate::new(333).unwrap(), minimum, idle, duration).is_none());
+        assert!(Config::new(rate, idle, minimum, duration).is_none());
+    }
 }