succd: factor out ringbuffer, do not recalculate average on every request

succbone/succd/process.go

@@ -66,6 +66,33 @@ func (t *thresholdOutput) process(value float64) {
 	}
 }
 
+// ringbufferInput accumulates analog data up to limit samples, and calculates
+// an average.
+type ringbufferInput struct {
+	data  []float32
+	limit uint
+	avg   float32
+}
+
+func (r *ringbufferInput) process(input float32) {
+	// TODO(q3k): use actual ringbuffer
+	// TODO(q3k): optimize average calculation
+	// TODO(q3k): precalculate value in mbar
+	r.data = append(r.data, input)
+	trim := len(r.data) - int(r.limit)
+	if trim > 0 {
+		r.data = r.data[trim:]
+	}
+	avg := float32(0.0)
+	for _, v := range r.data {
+		avg += v
+	}
+	if len(r.data) != 0 {
+		avg /= float32(len(r.data))
+	}
+	r.avg = avg
+}
+
 // process runs the pain acquisition and control loop of succd.
 func (d *daemon) process(ctx context.Context) {
 	ticker := time.NewTicker(time.Millisecond * 100)
@@ -96,12 +123,9 @@ func (d *daemon) processOnce(_ context.Context) error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 
-	// Process pirani ringbuffer.
-	d.adcPiraniVolts = append(d.adcPiraniVolts, v)
-	trim := len(d.adcPiraniVolts) - 100
-	if trim > 0 {
-		d.adcPiraniVolts = d.adcPiraniVolts[trim:]
-	}
+	// Process pirani ringbuffers.
+	d.piraniVolts3.process(v)
+	d.piraniVolts100.process(v)
 
 	d.pumpdown.process()
 	d.vent.process()