mavlink-mission: use mavlink_mission_item for crc calculation

src/modules/mavlink/mavlink_mission.cpp

@@ -75,7 +75,7 @@ static constexpr int MISSION_ITEM_CRC_SIZE = 32;
 		 (_msg.target_component == MAV_COMP_ID_ALL)))
 
 
-static uint32_t crc32_for_mission_item(const mission_item_s &mission_item, uint32_t prev_crc32)
+static uint32_t crc32_for_mission_item(const mavlink_mission_item_t &mission_item, uint32_t prev_crc32)
 {
 	union {
 		struct __attribute__((packed)) {
@@ -88,12 +88,15 @@ static uint32_t crc32_for_mission_item(const mission_item_s &mission_item, uint3
 	} u;
 
 	u.item.frame = mission_item.frame;
-	u.item.command = mission_item.nav_cmd;
+	u.item.command = mission_item.command;
 	u.item.autocontinue = mission_item.autocontinue;
-
-	for (int i = 0; i < 7; i++) {
-		u.item.params[i] = mission_item.params[i];
-	}
+	u.item.params[0] = mission_item.param1;
+	u.item.params[1] = mission_item.param2;
+	u.item.params[2] = mission_item.param3;
+	u.item.params[3] = mission_item.param4;
+	u.item.params[4] = mission_item.x;
+	u.item.params[5] = mission_item.y;
+	u.item.params[6] = mission_item.z;
 
 	return crc32part(u.raw, sizeof(u), prev_crc32);
 }
@@ -325,7 +328,12 @@ MavlinkMissionManager::send_mission_current(int32_t seq)
 	}
 }
 
-
+/**
+ * Combines two independently computed CRC32 checksums to a single checksum
+ * that is the same as if the checksum was computed over the concatenation
+ * of both blocks.
+ * Reference: https://stackoverflow.com/questions/23122312/crc-calculation-of-a-mostly-static-data-stream
+ */
 uint32_t crc32combine(uint32_t crc_a, uint32_t crc_b, size_t len_b)
 {
 	size_t i;
@@ -679,7 +687,6 @@ MavlinkMissionManager::handle_message(const mavlink_message_t *msg)
 		break;
 
 	case MAVLINK_MSG_ID_COMMAND_INT:
-		printf("GOT A COMMAND\n");
 		break;
 
 	default:
@@ -1192,7 +1199,7 @@ MavlinkMissionManager::handle_mission_item_both(const mavlink_message_t *msg)
 			return;
 		}
 
-		_transfer_current_crc32 = crc32_for_mission_item(mission_item, _transfer_current_crc32);
+		_transfer_current_crc32 = crc32_for_mission_item(wp, _transfer_current_crc32);
 
 		bool write_failed = false;
 		bool check_failed = false;