From b0351cd339f097db178cdb27b66b4259183630d2 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Wed, 16 Nov 2022 16:38:03 +1100
Subject: [PATCH] AP_GPS: protect detection structures with GPS backend defines

Save some memory when backends are compiled out
---
 libraries/AP_GPS/AP_GPS.h           | 12 ++++++++++++
 libraries/AP_GPS/GPS_detect_state.h | 15 ++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_GPS/AP_GPS.h b/libraries/AP_GPS/AP_GPS.h
index fc8227d0d8a8c..70879831078eb 100644
--- a/libraries/AP_GPS/AP_GPS.h
+++ b/libraries/AP_GPS/AP_GPS.h
@@ -686,12 +686,24 @@ class AP_GPS
         uint8_t current_baud;
         uint32_t probe_baud;
         bool auto_detected_baud;
+#if AP_GPS_UBLOX_ENABLED
         struct UBLOX_detect_state ublox_detect_state;
+#endif
+#if AP_GPS_SIRF_ENABLED
         struct SIRF_detect_state sirf_detect_state;
+#endif
+#if AP_GPS_NMEA_ENABLED
         struct NMEA_detect_state nmea_detect_state;
+#endif
+#if AP_GPS_SBP_ENABLED
         struct SBP_detect_state sbp_detect_state;
+#endif
+#if AP_GPS_SBP2_ENABLED
         struct SBP2_detect_state sbp2_detect_state;
+#endif
+#if AP_GPS_ERB_ENABLED
         struct ERB_detect_state erb_detect_state;
+#endif
     } detect_state[GPS_MAX_RECEIVERS];
 
     struct {
diff --git a/libraries/AP_GPS/GPS_detect_state.h b/libraries/AP_GPS/GPS_detect_state.h
index be6012fb7a5f2..bdc5d34e059b7 100644
--- a/libraries/AP_GPS/GPS_detect_state.h
+++ b/libraries/AP_GPS/GPS_detect_state.h
@@ -25,28 +25,39 @@
   specific type that it handles.
  */
 
+#include "AP_GPS_config.h"
+
+#if AP_GPS_NMEA_ENABLED
 struct NMEA_detect_state {
     uint8_t step;
     uint8_t ck;
 };
+#endif
 
+#if AP_GPS_SIRF_ENABLED
 struct SIRF_detect_state {
     uint16_t checksum;
     uint8_t step, payload_length, payload_counter;
 };
+#endif
 
+#if AP_GPS_UBLOX_ENABLED
 struct UBLOX_detect_state {
     uint8_t payload_length, payload_counter;
     uint8_t step;
     uint8_t ck_a, ck_b;
 };
+#endif
 
+#if AP_GPS_ERB_ENABLED
 struct ERB_detect_state {
     uint8_t payload_length, payload_counter;
     uint8_t step;
     uint8_t ck_a, ck_b;
 };
+#endif
 
+#if AP_GPS_SBP_ENABLED
 struct SBP_detect_state {
     enum {
         WAITING = 0,
@@ -63,8 +74,9 @@ struct SBP_detect_state {
     uint16_t crc;
     uint8_t heartbeat_buff[4];
 };
+#endif
 
-
+#if AP_GPS_SBP2_ENABLED
 struct SBP2_detect_state {
     enum {
         WAITING = 0,
@@ -81,3 +93,4 @@ struct SBP2_detect_state {
     uint16_t crc;
     uint8_t heartbeat_buff[4];
 };
+#endif