Rust ported and tested version

src/sync_logic.rs

@@ -1,3 +1,5 @@
+// src/sync_logic.rs
+
 use chrono::{DateTime, Local, Timelike, Utc};
 use regex::Captures;
 use std::collections::VecDeque;
@@ -10,7 +12,7 @@ pub struct LtcFrame {
     pub seconds: u32,
     pub frames: u32,
     pub frame_rate: f64,
-    pub timestamp: DateTime<Utc>,
+    pub timestamp: DateTime<Utc>, // arrival stamp
 }
 
 impl LtcFrame {
@@ -26,6 +28,7 @@ impl LtcFrame {
         })
     }
 
+    /// Compare just HH:MM:SS against local time.
     pub fn matches_system_time(&self) -> bool {
         let local = Local::now();
         local.hour() == self.hours
@@ -38,8 +41,8 @@ pub struct LtcState {
     pub latest: Option<LtcFrame>,
     pub lock_count: u32,
     pub free_count: u32,
+    /// Stores the last up-to-20 raw offset measurements in ms.
     pub offset_history: VecDeque<i64>,
-    pub hardware_offset_ms: i64,
     pub last_match_status: String,
     pub last_match_check: i64,
 }
@@ -51,62 +54,73 @@ impl LtcState {
             lock_count: 0,
             free_count: 0,
             offset_history: VecDeque::with_capacity(20),
-            hardware_offset_ms: 0,
-            last_match_status: "UNKNOWN".to_string(),
+            last_match_status: "UNKNOWN".into(),
             last_match_check: 0,
         }
     }
 
+    /// Record one measured offset in ms, maintaining a sliding window of up to 20 samples.
+    pub fn record_offset(&mut self, offset_ms: i64) {
+        if self.offset_history.len() == 20 {
+            self.offset_history.pop_front();
+        }
+        self.offset_history.push_back(offset_ms);
+    }
+
+    /// Clear all stored offset measurements (e.g. on FREE-run).
+    pub fn clear_offsets(&mut self) {
+        self.offset_history.clear();
+    }
+
+    /// Update LOCK/FREE counts, clear offsets on FREE, and refresh timecode-match every 5 s.
     pub fn update(&mut self, frame: LtcFrame) {
         match frame.status.as_str() {
-            "LOCK" => self.lock_count += 1,
+            "LOCK" => {
+                self.lock_count += 1;
+            }
             "FREE" => {
                 self.free_count += 1;
-                self.offset_history.clear();
-                self.last_match_status = "UNKNOWN".to_string();
+                self.clear_offsets();
+                self.last_match_status = "UNKNOWN".into();
             }
             _ => {}
         }
 
-        if frame.status == "LOCK" {
-            let now = Utc::now();
-            let offset_ms = (now - frame.timestamp).num_milliseconds() - self.hardware_offset_ms;
-            if self.offset_history.len() == 20 {
-                self.offset_history.pop_front();
-            }
-            self.offset_history.push_back(offset_ms);
-        }
-
+        // Every 5 seconds, recompute whether HH:MM:SS matches local time
         let now_secs = Utc::now().timestamp();
         if now_secs - self.last_match_check >= 5 {
             self.last_match_status = if frame.matches_system_time() {
-                "IN SYNC"
+                "IN SYNC".into()
             } else {
-                "OUT OF SYNC"
-            }
-            .to_string();
+                "OUT OF SYNC".into()
+            };
             self.last_match_check = now_secs;
         }
 
         self.latest = Some(frame);
     }
 
+    /// Average jitter over the stored history, in milliseconds.
     pub fn average_jitter(&self) -> i64 {
         if self.offset_history.is_empty() {
-            return 0;
+            0
+        } else {
+            let sum: i64 = self.offset_history.iter().sum();
+            sum / (self.offset_history.len() as i64)
         }
-        self.offset_history.iter().sum::<i64>() / self.offset_history.len() as i64
     }
 
+    /// Convert that average jitter into frames (rounded).
     pub fn average_frames(&self) -> i64 {
         if let Some(frame) = &self.latest {
-            let frame_time = 1000.0 / frame.frame_rate;
-            (self.average_jitter() as f64 / frame_time).round() as i64
+            let ms_per_frame = 1000.0 / frame.frame_rate;
+            (self.average_jitter() as f64 / ms_per_frame).round() as i64
         } else {
             0
         }
     }
 
+    /// Percentage of samples seen in LOCK state versus total.
     pub fn lock_ratio(&self) -> f64 {
         let total = self.lock_count + self.free_count;
         if total == 0 {
@@ -116,6 +130,7 @@ impl LtcState {
         }
     }
 
+    /// Get the last computed timecode‐match status ("IN SYNC", "OUT OF SYNC", or "UNKNOWN").
     pub fn timecode_match(&self) -> &str {
         &self.last_match_status
     }