From b3c227160037d8f5d5c6c074f93fb7e65990dc1e Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Fri, 16 Feb 2024 10:37:34 +1100
Subject: [PATCH] AP_ExternalAHRS: added support for GPS disable and fwd flight

allow backends to determine if we are in fixed wing flight and/or the
GPS is disabled by the user
---
 libraries/AP_ExternalAHRS/AP_ExternalAHRS.h        | 10 +++++++++-
 .../AP_ExternalAHRS/AP_ExternalAHRS_backend.cpp    |  6 ++++++
 .../AP_ExternalAHRS/AP_ExternalAHRS_backend.h      | 14 +++++++++++++-
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_ExternalAHRS/AP_ExternalAHRS.h b/libraries/AP_ExternalAHRS/AP_ExternalAHRS.h
index dfc81532c2734..e3a3a992cdecd 100644
--- a/libraries/AP_ExternalAHRS/AP_ExternalAHRS.h
+++ b/libraries/AP_ExternalAHRS/AP_ExternalAHRS.h
@@ -165,7 +165,12 @@ class AP_ExternalAHRS {
         float differential_pressure; // Pa
         float temperature; // degC
     } airspeed_data_message_t;
-    
+
+    // set GNSS disable for auxillary function GPS_DISABLE
+    void set_gnss_disable(bool disable) {
+        gnss_is_disabled = disable;
+    }
+
 protected:
 
     enum class OPTIONS {
@@ -195,6 +200,9 @@ class AP_ExternalAHRS {
     }
 
     uint32_t last_log_ms;
+
+    // true when user has disabled the GNSS
+    bool gnss_is_disabled;
 };
 
 namespace AP {
diff --git a/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.cpp b/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.cpp
index eaff493f5af3f..94cf8c41b7d2b 100644
--- a/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.cpp
+++ b/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.cpp
@@ -17,6 +17,7 @@
  */
 
 #include "AP_ExternalAHRS_backend.h"
+#include <AP_AHRS/AP_AHRS.h>
 
 #if HAL_EXTERNAL_AHRS_ENABLED
 
@@ -37,5 +38,10 @@ bool AP_ExternalAHRS_backend::option_is_set(AP_ExternalAHRS::OPTIONS option) con
     return frontend.option_is_set(option);
 }
 
+bool AP_ExternalAHRS_backend::in_fly_forward(void) const
+{
+    return AP::ahrs().get_fly_forward();
+}
+
 #endif  // HAL_EXTERNAL_AHRS_ENABLED
 
diff --git a/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.h b/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.h
index 02eb1b5319b7d..ed987a01ced3a 100644
--- a/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.h
+++ b/libraries/AP_ExternalAHRS/AP_ExternalAHRS_backend.h
@@ -57,7 +57,19 @@ class AP_ExternalAHRS_backend {
     void set_default_sensors(uint16_t sensors) {
         frontend.set_default_sensors(sensors);
     }
-    
+
+    /*
+      return true if the GNSS is disabled
+     */
+    bool gnss_is_disabled(void) const {
+        return frontend.gnss_is_disabled;
+    }
+
+    /*
+      return true when we are in fixed wing flight
+     */
+    bool in_fly_forward(void) const;
+
 private:
     AP_ExternalAHRS &frontend;
 };