From cfca75204f723b9c44d93e81a80a8b46fa516f9a Mon Sep 17 00:00:00 2001
From: Martin Budden <mjbudden@gmail.com>
Date: Sat, 25 Nov 2017 08:37:25 +0000
Subject: [PATCH] Removed unnecessary acc calculation when no alt hold

---
 src/main/flight/imu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/main/flight/imu.c b/src/main/flight/imu.c
index 851c083e0..3e8a1f952 100644
--- a/src/main/flight/imu.c
+++ b/src/main/flight/imu.c
@@ -178,6 +178,7 @@ void imuResetAccelerationSum(void)
     accTimeSum = 0;
 }
 
+#if defined(USE_ALT_HOLD)
 static void imuTransformVectorBodyToEarth(t_fp_vector * v)
 {
     /* From body frame to earth frame */
@@ -227,6 +228,7 @@ static void imuCalculateAcceleration(uint32_t deltaT)
     accTimeSum += deltaT;
     accSumCount++;
 }
+#endif // USE_ALT_HOLD
 
 static float invSqrt(float x)
 {
@@ -452,7 +454,9 @@ static void imuCalculateEstimatedAttitude(timeUs_t currentTimeUs)
 
     imuUpdateEulerAngles();
 #endif
+#if defined(USE_ALT_HOLD)
     imuCalculateAcceleration(deltaT); // rotate acc vector into earth frame
+#endif
 }
 
 void imuUpdateAttitude(timeUs_t currentTimeUs)