From 4299eb9ba8d647dd56bf1a94666a294e3bb5c4e1 Mon Sep 17 00:00:00 2001
From: Michael du Breuil <wicked.shell.scripts@gmail.com>
Date: Thu, 28 Jun 2018 14:57:49 -0700
Subject: [PATCH] AP_Terrain: Reduce memory consumption, simplify enable
 checking

---
 libraries/AP_Terrain/AP_Terrain.cpp | 21 +++++----------------
 libraries/AP_Terrain/TerrainGCS.cpp |  2 +-
 2 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/libraries/AP_Terrain/AP_Terrain.cpp b/libraries/AP_Terrain/AP_Terrain.cpp
index 28760df9cc..bed36dc563 100644
--- a/libraries/AP_Terrain/AP_Terrain.cpp
+++ b/libraries/AP_Terrain/AP_Terrain.cpp
@@ -61,20 +61,9 @@ AP_Terrain::AP_Terrain(AP_AHRS &_ahrs, const AP_Mission &_mission, const AP_Rall
     mission(_mission),
     rally(_rally),
     disk_io_state(DiskIoIdle),
-    fd(-1),
-    timer_setup(false),
-    file_lat_degrees(0),
-    file_lon_degrees(0),
-    io_failure(false),
-    directory_created(false),
-    home_height(0),
-    have_current_loc_height(false),
-    last_current_loc_height(0)
+    fd(-1)
 {
     AP_Param::setup_object_defaults(this, var_info);
-    memset(&home_loc, 0, sizeof(home_loc));
-    memset(&disk_block, 0, sizeof(disk_block));
-    memset(last_request_time_ms, 0, sizeof(last_request_time_ms));
 }
 
 /*
@@ -88,7 +77,7 @@ AP_Terrain::AP_Terrain(AP_AHRS &_ahrs, const AP_Mission &_mission, const AP_Rall
  */
 bool AP_Terrain::height_amsl(const Location &loc, float &height, bool corrected)
 {
-    if (!enable || !allocate()) {
+    if (!allocate()) {
         return false;
     }
 
@@ -260,7 +249,7 @@ bool AP_Terrain::height_relative_home_equivalent(float terrain_altitude,
 */
 float AP_Terrain::lookahead(float bearing, float distance, float climb_ratio)
 {
-    if (!enable || !allocate() || grid_spacing <= 0) {
+    if (!allocate() || grid_spacing <= 0) {
         return 0;
     }
 
@@ -326,7 +315,7 @@ void AP_Terrain::update(void)
     update_rally_data();
 
     // update capabilities and status
-    if (enable) {
+    if (allocate()) {
         hal.util->set_capabilities(MAV_PROTOCOL_CAPABILITY_TERRAIN);
         if (!pos_valid) {
             // we don't know where we are
@@ -349,7 +338,7 @@ void AP_Terrain::update(void)
  */
 void AP_Terrain::log_terrain_data(DataFlash_Class &dataflash)
 {
-    if (!enable) {
+    if (!allocate()) {
         return;
     }
     Location loc;
diff --git a/libraries/AP_Terrain/TerrainGCS.cpp b/libraries/AP_Terrain/TerrainGCS.cpp
index 8c9834546a..d23139ed04 100644
--- a/libraries/AP_Terrain/TerrainGCS.cpp
+++ b/libraries/AP_Terrain/TerrainGCS.cpp
@@ -83,7 +83,7 @@ bool AP_Terrain::request_missing(mavlink_channel_t chan, const struct grid_info
  */
 void AP_Terrain::send_request(mavlink_channel_t chan)
 {
-    if (enable == 0 || !allocate()) {
+    if (!allocate()) {
         // not enabled
         return;
     }