⚡ Bolt: Optimize cold start enrichment hot path

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-04-19 - Optimization of cold start enrichment hot path
+**Learning:** In high-frequency loops (like `updateTorque` running at 2000Hz), defining functions and tables locally causes excessive garbage collection pressure due to constant allocations.
+**Action:** Move static data structures and helper functions to the module level to avoid re-allocation in the hot path.

combustionEngine.lua

@@ -36,6 +36,49 @@ local torqueToPower = 0.0001404345295653085
 local psToWatt = 735.499
 local hydrolockThreshold = 1.9
 
+-- Cold start enrichment using temperature-based lookup table
+local enrichmentMap = {
+  [-30] = 3.0,
+  [-20] = 2.6,
+  [-10] = 2.2,
+  [0] = 1.8,
+  [10] = 1.5,
+  [20] = 1.3,
+  [30] = 1.15,
+  [40] = 1.05,
+  [50] = 1.02,
+  [60] = 1.0,
+  [70] = 1.0
+}
+
+local function getColdEnrichment(tempC)
+  -- Find the two closest temperature points
+  local lowerTemp = -20
+  local upperTemp = 80
+  local lowerEnrich = 3.0
+  local upperEnrich = 0.85
+
+  -- Find the two closest temperature points in the map
+  for temp, enrich in pairs(enrichmentMap) do
+    if temp <= tempC and temp > lowerTemp then
+      lowerTemp = temp
+      lowerEnrich = enrich
+    end
+    if temp >= tempC and temp < upperTemp then
+      upperTemp = temp
+      upperEnrich = enrich
+    end
+  end
+
+  -- Linear interpolation between the two closest points
+  if lowerTemp == upperTemp then
+    return lowerEnrich
+  end
+
+  local t = (tempC - lowerTemp) / (upperTemp - lowerTemp)
+  return lowerEnrich + (upperEnrich - lowerEnrich) * t
+end
+
 local function getTorqueData(device)
   local curves = {}
   local curveCounter = 1
@@ -1241,52 +1284,7 @@ local function updateTorque(device, dt)
 
   -- Temperature effect on starter torque (reduces torque in cold conditions)
   local tempEffectOnStarter = 1.0 - math.max(0, math.min(0.7, (0 - engineTempC) / 30))
-
-  -- Cold start enrichment using temperature-based lookup table (reduced values)
-  local function getColdEnrichment(tempC)
-    -- Temperature in Celsius to enrichment factor mapping
-    -- [tempC] = enrichmentMultiplier
-    local enrichmentMap = {
-      [-30] = 3.0,  -- Reduced from 4.0
-      [-20] = 2.6,  -- Reduced from 3.5
-      [-10] = 2.2,  -- Reduced from 3.0
-      [0]   = 1.8,  -- Reduced from 2.5
-      [10]  = 1.5,  -- Reduced from 2.0
-      [20]  = 1.3,  -- Reduced from 1.5
-      [30]  = 1.15, -- Reduced from 1.25
-      [40]  = 1.05, -- Reduced from 1.1
-      [50]  = 1.02, -- Reduced from 1.05
-      [60]  = 1.0,
-      [70]  = 1.0
-    }
-
-    -- Find the two closest temperature points
-    local lowerTemp = -20
-    local upperTemp = 80
-    local lowerEnrich = 3.0
-    local upperEnrich = 0.85
-
-    -- Find the two closest temperature points in the map
-    for temp, _ in pairs(enrichmentMap) do
-      if temp <= tempC and temp > lowerTemp then
-        lowerTemp = temp
-        lowerEnrich = enrichmentMap[temp]
-      end
-      if temp >= tempC and temp < upperTemp then
-        upperTemp = temp
-        upperEnrich = enrichmentMap[temp]
-      end
-    end
-
-    -- Linear interpolation between the two closest points
-    if lowerTemp == upperTemp then
-      return lowerEnrich
-    end
-
-    local t = (tempC - lowerTemp) / (upperTemp - lowerTemp)
-    return lowerEnrich + (upperEnrich - lowerEnrich) * t
-  end
-
+
   -- Calculate cold start enrichment based on engine temperature
   local coldStartEnrichment = getColdEnrichment(engineTempC)