From 38251303b71f0b87047538e71a44ea32e835bf99 Mon Sep 17 00:00:00 2001
From: Victoria Fischer <tdfischer@hackerbots.net>
Date: Sat, 3 Jan 2026 14:45:37 +0100
Subject: [PATCH] build: add support for stream decimation when generating sim
 data

---
 build.rs | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/build.rs b/build.rs
index f487be5..73d264e 100644
--- a/build.rs
+++ b/build.rs
@@ -108,7 +108,7 @@ impl FromRecord for IMUReading {
     }
 }
 
-fn generate_sim_data<Event: EventRecord + FromRecord>(srcs: &[&Path], dest: &Path) {
+fn generate_sim_data<Event: EventRecord + FromRecord>(srcs: &[&Path], dest: &Path, skip_rate: usize) {
 
     for src in srcs {
         println!("cargo::rerun-if-changed={}", src.to_str().unwrap());
@@ -151,6 +151,8 @@ fn generate_sim_data<Event: EventRecord + FromRecord>(srcs: &[&Path], dest: &Pat
         reader.records()
     }).collect();
 
+    let mut skip_count = 0;
+
     loop {
         let mut next: Vec<_> = all_records.iter_mut().map(|reader| { reader.next() }).collect();
 
@@ -162,16 +164,22 @@ fn generate_sim_data<Event: EventRecord + FromRecord>(srcs: &[&Path], dest: &Pat
         let next: Vec<_> = next.iter_mut().map(|x| { x.take().unwrap().unwrap() }).collect();
 
         let data = Event::from_record(next.as_slice(), headers.as_slice());
-        eprintln!("next={next:?} headers={headers:?}");
+        //eprintln!("next={next:?} headers={headers:?}");
 
-        let timestamp = next[0].get(headers[0]["seconds_elapsed"]).unwrap().parse().unwrap();
-        let next_delay = timestamp - last_stamp;
-        last_stamp = timestamp;
+        let this_timecode: f64 = next[0].get(headers[0]["seconds_elapsed"]).unwrap().parse().unwrap();
+        let time_delta = this_timecode - last_stamp;
         let record = StreamEvent {
-            timecode: next_delay,
+            timecode: time_delta,
             data
         };
-        record.write_rmp(&mut output).unwrap();
+
+        if skip_count == 0 {
+            last_stamp = this_timecode;
+            record.write_rmp(&mut output).unwrap();
+            skip_count = skip_rate;
+        } else {
+            skip_count -= 1;
+        }
     }
 }
 
@@ -188,9 +196,9 @@ fn write_sim_data() {
     let annotation_output = output_path.join("annotations.msgpack");
     let unified_output = output_path.join("unified.msgpack");
 
-    generate_sim_data::<AnnotationReading>(&[&annotation_input], &annotation_output);
-    generate_sim_data::<GPSReading>(&[&gps_input], &gps_output);
-    generate_sim_data::<IMUReading>(&[&accel_input, &gyro_input], &motion_output);
+    generate_sim_data::<AnnotationReading>(&[&annotation_input], &annotation_output, 0);
+    generate_sim_data::<GPSReading>(&[&gps_input], &gps_output, 0);
+    generate_sim_data::<IMUReading>(&[&accel_input, &gyro_input], &motion_output, 2);
 
     let mut unified_fd = File::create(unified_output.clone()).unwrap();
 
@@ -230,7 +238,7 @@ fn write_sim_data() {
 
     if unified_fd.metadata().unwrap().len() as usize >= data_size {
         // FIXME: Need to implement data resampling
-        //panic!("Simulation data is too big! Cannot fit {:#x} bytes into a partition with a size of {data_size:#x} bytes.", unified_fd.metadata().unwrap().len());
+        panic!("Simulation data is too big! Cannot fit {:#x} bytes into a partition with a size of {data_size:#x} bytes.", unified_fd.metadata().unwrap().len());
     }
 
     let mut data_flash_script = File::create(output_path.join("flash-sim-data.sh")).unwrap();