From 407cfc22cad4f4e0ead44f9d464cf65a6dd539f7 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 18 Jul 2023 18:33:59 +1000
Subject: [PATCH] AP_GPS: remove code if blended instance is not available

---
 libraries/AP_Arming/AP_Arming.cpp |  2 ++
 libraries/AP_GPS/AP_GPS.cpp       | 11 ++++++++---
 libraries/AP_GPS/AP_GPS.h         |  2 ++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/libraries/AP_Arming/AP_Arming.cpp b/libraries/AP_Arming/AP_Arming.cpp
index c735236b6a..44a045ff5d 100644
--- a/libraries/AP_Arming/AP_Arming.cpp
+++ b/libraries/AP_Arming/AP_Arming.cpp
@@ -618,10 +618,12 @@ bool AP_Arming::gps_checks(bool report)
                          (double)distance_m);
             return false;
         }
+#if defined(GPS_BLENDED_INSTANCE)
         if (!gps.blend_health_check()) {
             check_failed(ARMING_CHECK_GPS, report, "GPS blending unhealthy");
             return false;
         }
+#endif
 
         // check AHRS and GPS are within 10m of each other
         if (gps.num_sensors() > 0) {
diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 62ec572a26..c6e24f10a3 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -470,8 +470,10 @@ void AP_GPS::init(const AP_SerialManager& serial_manager)
     }
     _last_instance_swap_ms = 0;
 
+#if defined(GPS_BLENDED_INSTANCE)
     // Initialise class variables used to do GPS blending
     _omega_lpf = 1.0f / constrain_float(_blend_tc, 5.0f, 30.0f);
+#endif
 
     // prep the state instance fields
     for (uint8_t i = 0; i < GPS_MAX_INSTANCES; i++) {
@@ -491,11 +493,12 @@ void AP_GPS::init(const AP_SerialManager& serial_manager)
 // GPS solution is treated as an additional sensor.
 uint8_t AP_GPS::num_sensors(void) const
 {
-    if (!_output_is_blended) {
-        return num_instances;
-    } else {
+#if defined(GPS_BLENDED_INSTANCE)
+    if (_output_is_blended) {
         return num_instances+1;
     }
+#endif
+    return num_instances;
 }
 
 bool AP_GPS::speed_accuracy(uint8_t instance, float &sacc) const
@@ -1542,11 +1545,13 @@ bool AP_GPS::all_consistent(float &distance) const
     return (distance < 50);
 }
 
+#if defined(GPS_BLENDED_INSTANCE)
 // pre-arm check of GPS blending.  True means healthy or that blending is not being used
 bool AP_GPS::blend_health_check() const
 {
     return (_blend_health_counter < 50);
 }
+#endif
 
 /*
    re-assemble fragmented RTCM data
diff --git a/libraries/AP_GPS/AP_GPS.h b/libraries/AP_GPS/AP_GPS.h
index ed66955ae5..83d271e6e0 100644
--- a/libraries/AP_GPS/AP_GPS.h
+++ b/libraries/AP_GPS/AP_GPS.h
@@ -730,6 +730,7 @@ private:
     void inject_data(const uint8_t *data, uint16_t len);
     void inject_data(uint8_t instance, const uint8_t *data, uint16_t len);
 
+#if defined(GPS_BLENDED_INSTANCE)
     // GPS blending and switching
     Vector3f _blended_antenna_offset; // blended antenna offset
     float _blended_lag_sec; // blended receiver lag in seconds
@@ -743,6 +744,7 @@ private:
 
     // calculate the blended state
     void calc_blended_state(void);
+#endif
 
     bool should_log() const;