diff --git a/libraries/AP_DAL/AP_DAL.cpp b/libraries/AP_DAL/AP_DAL.cpp
index fd89b4a978..0fa4a6886f 100644
--- a/libraries/AP_DAL/AP_DAL.cpp
+++ b/libraries/AP_DAL/AP_DAL.cpp
@@ -12,10 +12,6 @@
 
 extern const AP_HAL::HAL& hal;
 
-enum class FrameItem : uint8_t {
-    AVAILABLE_MEMORY = 0,
-};
-
 AP_DAL *AP_DAL::_singleton = nullptr;
 
 bool AP_DAL::force_write;
@@ -67,7 +63,7 @@ void AP_DAL::start_frame(AP_DAL::FrameType frametype)
     _RFRN.fly_forward = ahrs.get_fly_forward();
     _RFRN.ahrs_airspeed_sensor_enabled = AP::ahrs().airspeed_sensor_enabled();
     _RFRN.available_memory = hal.util->available_memory();
-    WRITE_REPLAY_BLOCK_IFCHANGD(RFRN, _RFRN, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RFRN, _RFRN, old);
 
     // update body conversion
     _rotation_vehicle_body_to_autopilot_body = ahrs.get_rotation_vehicle_body_to_autopilot_body();
@@ -274,7 +270,7 @@ void AP_DAL::writeOptFlowMeas(const uint8_t rawFlowQuality, const Vector2f &rawF
     _ROFH.rawGyroRates = rawGyroRates;
     _ROFH.msecFlowMeas = msecFlowMeas;
     _ROFH.posOffset = posOffset;
-    WRITE_REPLAY_BLOCK_IFCHANGD(ROFH, _ROFH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(ROFH, _ROFH, old);
 }
 
 // log external navigation data
@@ -290,7 +286,7 @@ void AP_DAL::writeExtNavData(const Vector3f &pos, const Quaternion &quat, float
     _REPH.timeStamp_ms = timeStamp_ms;
     _REPH.delay_ms = delay_ms;
     _REPH.resetTime_ms = resetTime_ms;
-    WRITE_REPLAY_BLOCK_IFCHANGD(REPH, _REPH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(REPH, _REPH, old);
 }
 
 // log external velocity data
@@ -303,7 +299,7 @@ void AP_DAL::writeExtNavVelData(const Vector3f &vel, float err, uint32_t timeSta
     _REVH.err = err;
     _REVH.timeStamp_ms = timeStamp_ms;
     _REVH.delay_ms = delay_ms;
-    WRITE_REPLAY_BLOCK_IFCHANGD(REVH, _REVH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(REVH, _REVH, old);
 
 }
 
@@ -318,7 +314,7 @@ void AP_DAL::writeWheelOdom(float delAng, float delTime, uint32_t timeStamp_ms,
     _RWOH.timeStamp_ms = timeStamp_ms;
     _RWOH.posOffset = posOffset;
     _RWOH.radius = radius;
-    WRITE_REPLAY_BLOCK_IFCHANGD(RWOH, _RWOH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RWOH, _RWOH, old);
 }
 
 void AP_DAL::writeBodyFrameOdom(float quality, const Vector3f &delPos, const Vector3f &delAng, float delTime, uint32_t timeStamp_ms, uint16_t delay_ms, const Vector3f &posOffset)
@@ -331,7 +327,7 @@ void AP_DAL::writeBodyFrameOdom(float quality, const Vector3f &delPos, const Vec
     _RBOH.delAng = delAng;
     _RBOH.delTime = delTime;
     _RBOH.timeStamp_ms = timeStamp_ms;
-    WRITE_REPLAY_BLOCK_IFCHANGD(RBOH, _RBOH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RBOH, _RBOH, old);
 }
 
 #if APM_BUILD_TYPE(APM_BUILD_Replay)
diff --git a/libraries/AP_DAL/AP_DAL.h b/libraries/AP_DAL/AP_DAL.h
index 78a875adda..4d415e3bfd 100644
--- a/libraries/AP_DAL/AP_DAL.h
+++ b/libraries/AP_DAL/AP_DAL.h
@@ -1,9 +1,5 @@
 #pragma once
 
-#include <stdint.h>
-
-#include <cstddef>
-
 #include "AP_DAL_InertialSensor.h"
 #include "AP_DAL_Baro.h"
 #include "AP_DAL_GPS.h"
@@ -15,6 +11,10 @@
 
 #include "LogStructure.h"
 
+#include <stdint.h>
+#include <cstddef>
+
+
 #define DAL_CORE(c) AP::dal().logging_core(c)
 
 #if APM_BUILD_TYPE(APM_BUILD_Replay)
@@ -25,16 +25,16 @@ class NavEKF3;
 class AP_DAL {
 public:
 
-    enum class FrameType {
-        InitialiseFilterEKF2 = 1<<0,
-        UpdateFilterEKF2 = 1<<1,
+    enum class FrameType : uint8_t {
+        InitialiseFilterEKF2 = 1U<<0,
+        UpdateFilterEKF2 = 1U<<1,
         InitialiseFilterEKF3 = 1<<2,
         UpdateFilterEKF3 = 1<<3,
         LogWriteEKF2 = 1<<4,
         LogWriteEKF3 = 1<<5,
     };
 
-    enum class Event2 {
+    enum class Event2 : uint8_t {
         resetGyroBias             =  0,
         resetHeightDatum          =  1,
         setInhibitGPS             =  2,
@@ -50,7 +50,7 @@ public:
         checkLaneSwitch           = 12,
     };
 
-    enum class Event3 {
+    enum class Event3 : uint8_t {
         resetGyroBias             =  0,
         resetHeightDatum          =  1,
         setInhibitGPS             =  2,
@@ -350,7 +350,7 @@ private:
 };
 
 #define WRITE_REPLAY_BLOCK(sname,v) AP_DAL::WriteLogMessage(LOG_## sname ##_MSG, &v, nullptr, offsetof(log_ ##sname, _end))
-#define WRITE_REPLAY_BLOCK_IFCHANGD(sname,v,old) do { static_assert(sizeof(v) == sizeof(old), "types must match"); \
+#define WRITE_REPLAY_BLOCK_IFCHANGED(sname,v,old) do { static_assert(sizeof(v) == sizeof(old), "types must match"); \
                                                       AP_DAL::WriteLogMessage(LOG_## sname ##_MSG, &v, &old, offsetof(log_ ##sname, _end)); } \
                                                  while (0)
 
diff --git a/libraries/AP_DAL/AP_DAL_Airspeed.cpp b/libraries/AP_DAL/AP_DAL_Airspeed.cpp
index 82aa1f0d34..86111e46aa 100644
--- a/libraries/AP_DAL/AP_DAL_Airspeed.cpp
+++ b/libraries/AP_DAL/AP_DAL_Airspeed.cpp
@@ -20,7 +20,7 @@ void AP_DAL_Airspeed::start_frame()
     const log_RASH old = _RASH;
     _RASH.num_sensors = airspeed->get_num_sensors();
     _RASH.primary = airspeed->get_primary();
-    WRITE_REPLAY_BLOCK_IFCHANGD(RASH, _RASH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RASH, _RASH, old);
 
     for (uint8_t i=0; i<ARRAY_SIZE(_RASI); i++) {
         log_RASI &RASI = _RASI[i];
@@ -29,6 +29,6 @@ void AP_DAL_Airspeed::start_frame()
         RASI.healthy = airspeed->healthy(i);
         RASI.use = airspeed->use(i);
         RASI.airspeed = airspeed->get_airspeed(i);
-        WRITE_REPLAY_BLOCK_IFCHANGD(RASI, RASI, old_RASI);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RASI, RASI, old_RASI);
     }
 }
diff --git a/libraries/AP_DAL/AP_DAL_Baro.cpp b/libraries/AP_DAL/AP_DAL_Baro.cpp
index f779d4c0cc..ad4d3ad0a5 100644
--- a/libraries/AP_DAL/AP_DAL_Baro.cpp
+++ b/libraries/AP_DAL/AP_DAL_Baro.cpp
@@ -17,16 +17,16 @@ void AP_DAL_Baro::start_frame()
     const log_RBRH old_RBRH = _RBRH;
     _RBRH.primary = baro.get_primary();
     _RBRH.num_instances = baro.num_instances();
-    WRITE_REPLAY_BLOCK_IFCHANGD(RBRH, _RBRH, old_RBRH);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RBRH, _RBRH, old_RBRH);
 
-    for (uint8_t i=0; i<BARO_MAX_INSTANCES; i++) {
+    for (uint8_t i=0; i<_RBRH.num_instances; i++) {
         log_RBRI &RBRI = _RBRI[i];
         log_RBRI old = RBRI;
         const uint32_t last_update_ms = baro.get_last_update(i);
         RBRI.last_update_ms = last_update_ms;
         RBRI.healthy = baro.healthy(i);
         RBRI.altitude = baro.get_altitude(i);
-        WRITE_REPLAY_BLOCK_IFCHANGD(RBRI, _RBRI[i], old);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RBRI, _RBRI[i], old);
     }
 }
 
diff --git a/libraries/AP_DAL/AP_DAL_Beacon.cpp b/libraries/AP_DAL/AP_DAL_Beacon.cpp
index 2cf9444dd9..f731855f94 100644
--- a/libraries/AP_DAL/AP_DAL_Beacon.cpp
+++ b/libraries/AP_DAL/AP_DAL_Beacon.cpp
@@ -28,7 +28,7 @@ void AP_DAL_Beacon::start_frame()
         _RBCH.origin_lng = loc.lng;
         _RBCH.origin_alt = loc.alt;
     }
-    WRITE_REPLAY_BLOCK_IFCHANGD(RBCH, _RBCH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RBCH, _RBCH, old);
     if (bcon == nullptr) {
         return;
     }
@@ -41,6 +41,6 @@ void AP_DAL_Beacon::start_frame()
         RBCI.distance = bcon->beacon_distance(i);
         RBCI.healthy = bcon->beacon_healthy(i);
 
-        WRITE_REPLAY_BLOCK_IFCHANGD(RBCI, RBCI, old_RBCI);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RBCI, RBCI, old_RBCI);
     }
 }
diff --git a/libraries/AP_DAL/AP_DAL_Compass.cpp b/libraries/AP_DAL/AP_DAL_Compass.cpp
index 21a427e22a..fd809cbceb 100644
--- a/libraries/AP_DAL/AP_DAL_Compass.cpp
+++ b/libraries/AP_DAL/AP_DAL_Compass.cpp
@@ -23,9 +23,9 @@ void AP_DAL_Compass::start_frame()
     _RMGH.num_enabled = compass.get_num_enabled();
     _RMGH.consistent = compass.consistent();
 
-    WRITE_REPLAY_BLOCK_IFCHANGD(RMGH, _RMGH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RMGH, _RMGH, old);
 
-    for (uint8_t i=0; i<ARRAY_SIZE(_RMGI); i++) {
+    for (uint8_t i=0; i<_RMGH.count; i++) {
         log_RMGI &RMGI = _RMGI[i];
         const log_RMGI old_RMGI = RMGI;
         RMGI.use_for_yaw = compass.use_for_yaw(i);
@@ -35,6 +35,6 @@ void AP_DAL_Compass::start_frame()
         RMGI.last_update_usec = compass.last_update_usec(i);
         RMGI.field = compass.get_field(i);
 
-        WRITE_REPLAY_BLOCK_IFCHANGD(RMGI, RMGI, old_RMGI);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RMGI, RMGI, old_RMGI);
     }
 }
diff --git a/libraries/AP_DAL/AP_DAL_GPS.cpp b/libraries/AP_DAL/AP_DAL_GPS.cpp
index 4f9d70bcff..132d63c88c 100644
--- a/libraries/AP_DAL/AP_DAL_GPS.cpp
+++ b/libraries/AP_DAL/AP_DAL_GPS.cpp
@@ -19,7 +19,7 @@ void AP_DAL_GPS::start_frame()
     _RGPH.primary_sensor = gps.primary_sensor();
     _RGPH.num_sensors = gps.num_sensors();
 
-    WRITE_REPLAY_BLOCK_IFCHANGD(RGPH, _RGPH, old_RGPH);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RGPH, _RGPH, old_RGPH);
 
     for (uint8_t i=0; i<ARRAY_SIZE(_RGPI); i++) {
         log_RGPI &RGPI = _RGPI[i];
@@ -39,7 +39,7 @@ void AP_DAL_GPS::start_frame()
         RGPI.hdop = gps.get_hdop(i);
         RGPI.num_sats = gps.num_sats(i);
         RGPI.get_lag_returncode = gps.get_lag(i, RGPI.lag_sec);
-        WRITE_REPLAY_BLOCK_IFCHANGD(RGPI, RGPI, old_RGPI);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RGPI, RGPI, old_RGPI);
 
         log_RGPJ &RGPJ = _RGPJ[i];
         const log_RGPJ old_RGPJ = RGPJ;
@@ -47,7 +47,7 @@ void AP_DAL_GPS::start_frame()
         RGPJ.velocity = gps.velocity(i);
         RGPJ.speed_accuracy_returncode = gps.speed_accuracy(i, RGPJ.sacc);
         RGPJ.gps_yaw_deg_returncode = gps.gps_yaw_deg(i, RGPJ.yaw_deg, RGPJ.yaw_accuracy_deg);
-        WRITE_REPLAY_BLOCK_IFCHANGD(RGPJ, RGPJ, old_RGPJ);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RGPJ, RGPJ, old_RGPJ);
 
         // also fetch antenna offset for this frame
         antenna_offset[i] = gps.get_antenna_offset(i);
diff --git a/libraries/AP_DAL/AP_DAL_InertialSensor.cpp b/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
index 36d0dc205c..26f2f8b778 100644
--- a/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
+++ b/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
@@ -23,7 +23,7 @@ void AP_DAL_InertialSensor::start_frame()
     _RISH.primary_accel = ins.get_primary_accel();
     _RISH.accel_count = ins.get_accel_count();
     _RISH.gyro_count = ins.get_gyro_count();
-    WRITE_REPLAY_BLOCK_IFCHANGD(RISH, _RISH, old_RISH);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RISH, _RISH, old_RISH);
 
     for (uint8_t i=0; i<ARRAY_SIZE(_RISI); i++) {
         log_RISI &RISI = _RISI[i];
@@ -41,7 +41,7 @@ void AP_DAL_InertialSensor::start_frame()
 
         update_filtered(i);
 
-        WRITE_REPLAY_BLOCK_IFCHANGD(RISI, RISI, old_RISI);
+        WRITE_REPLAY_BLOCK_IFCHANGED(RISI, RISI, old_RISI);
 
         // update sensor position
         pos[i] = ins.get_imu_pos_offset(i);
diff --git a/libraries/AP_DAL/AP_DAL_RangeFinder.cpp b/libraries/AP_DAL/AP_DAL_RangeFinder.cpp
index 584c3ea388..d9939a9ff6 100644
--- a/libraries/AP_DAL/AP_DAL_RangeFinder.cpp
+++ b/libraries/AP_DAL/AP_DAL_RangeFinder.cpp
@@ -57,7 +57,7 @@ void AP_DAL_RangeFinder::start_frame()
     // EKF only asks for this *down*.
     const log_RRNH old = _RRNH;
     _RRNH.ground_clearance_cm = rangefinder->ground_clearance_cm_orient(ROTATION_PITCH_270);
-    _RRNH.max_distance_cm = rangefinder->ground_clearance_cm_orient(ROTATION_PITCH_270);
+    _RRNH.max_distance_cm = rangefinder->max_distance_cm_orient(ROTATION_PITCH_270);
     _RRNH.backend_mask = 0;
 
     for (uint8_t i=0; i<RANGEFINDER_MAX_INSTANCES; i++) {
@@ -69,7 +69,7 @@ void AP_DAL_RangeFinder::start_frame()
         _backend[i]->start_frame(backend);
     }
 
-    WRITE_REPLAY_BLOCK_IFCHANGD(RRNH, _RRNH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RRNH, _RRNH, old);
 }
 
 
@@ -85,7 +85,7 @@ void AP_DAL_RangeFinder_Backend::start_frame(AP_RangeFinder_Backend *backend) {
     _RRNI.orientation = backend->orientation();
     _RRNI.status = (uint8_t)backend->status();
     _RRNI.pos_offset = backend->get_pos_offset();
-    WRITE_REPLAY_BLOCK_IFCHANGD(RRNI, _RRNI, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RRNI, _RRNI, old);
 }
 
 
diff --git a/libraries/AP_DAL/AP_DAL_VisualOdom.cpp b/libraries/AP_DAL/AP_DAL_VisualOdom.cpp
index fa7cdbf545..d24c04a184 100644
--- a/libraries/AP_DAL/AP_DAL_VisualOdom.cpp
+++ b/libraries/AP_DAL/AP_DAL_VisualOdom.cpp
@@ -7,10 +7,6 @@
 #include <AP_Logger/AP_Logger.h>
 #include "AP_DAL.h"
 
-AP_DAL_VisualOdom::AP_DAL_VisualOdom()
-{
-}
-
 void AP_DAL_VisualOdom::start_frame()
 {
     const auto *vo = AP::visualodom();
@@ -21,7 +17,7 @@ void AP_DAL_VisualOdom::start_frame()
         RVOH.healthy = vo->healthy();
     }
 
-    WRITE_REPLAY_BLOCK_IFCHANGD(RVOH, RVOH, old);
+    WRITE_REPLAY_BLOCK_IFCHANGED(RVOH, RVOH, old);
 }
 
 #endif // HAL_VISUALODOM_ENABLED
diff --git a/libraries/AP_DAL/AP_DAL_VisualOdom.h b/libraries/AP_DAL/AP_DAL_VisualOdom.h
index 6d987ab95b..9ae8f4a543 100644
--- a/libraries/AP_DAL/AP_DAL_VisualOdom.h
+++ b/libraries/AP_DAL/AP_DAL_VisualOdom.h
@@ -29,9 +29,6 @@ public:
         return RVOH.pos_offset;
     }
 
-    // AP_DAL methods:
-    AP_DAL_VisualOdom();
-
     AP_DAL_VisualOdom *visualodom() {
         if (RVOH.ptr_is_nullptr) {
             return nullptr;