mirror of https://github.com/ArduPilot/ardupilot
408 lines
12 KiB
C++
408 lines
12 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __AP_TERRAIN_H__
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#define __AP_TERRAIN_H__
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#include <AP_Common.h>
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#include <AP_HAL.h>
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#include <DataFlash.h>
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#if HAL_OS_POSIX_IO && defined(HAL_BOARD_TERRAIN_DIRECTORY)
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#define AP_TERRAIN_AVAILABLE 1
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#else
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#define AP_TERRAIN_AVAILABLE 0
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#endif
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#if AP_TERRAIN_AVAILABLE
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#include <AP_Param.h>
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#include <AP_AHRS.h>
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#include <AP_Mission.h>
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#include <AP_Rally.h>
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#define TERRAIN_DEBUG 0
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// MAVLink sends 4x4 grids
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#define TERRAIN_GRID_MAVLINK_SIZE 4
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// a 2k grid_block on disk contains 8x7 of the mavlink grids. Each
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// grid block overlaps by one with its neighbour. This ensures that
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// the altitude at any point can be calculated from a single grid
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// block
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#define TERRAIN_GRID_BLOCK_MUL_X 7
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#define TERRAIN_GRID_BLOCK_MUL_Y 8
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// this is the spacing between 32x28 grid blocks, in grid_spacing units
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#define TERRAIN_GRID_BLOCK_SPACING_X ((TERRAIN_GRID_BLOCK_MUL_X-1)*TERRAIN_GRID_MAVLINK_SIZE)
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#define TERRAIN_GRID_BLOCK_SPACING_Y ((TERRAIN_GRID_BLOCK_MUL_Y-1)*TERRAIN_GRID_MAVLINK_SIZE)
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// giving a total grid size of a disk grid_block of 32x28
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#define TERRAIN_GRID_BLOCK_SIZE_X (TERRAIN_GRID_MAVLINK_SIZE*TERRAIN_GRID_BLOCK_MUL_X)
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#define TERRAIN_GRID_BLOCK_SIZE_Y (TERRAIN_GRID_MAVLINK_SIZE*TERRAIN_GRID_BLOCK_MUL_Y)
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// number of grid_blocks in the LRU memory cache
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#define TERRAIN_GRID_BLOCK_CACHE_SIZE 12
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// format of grid on disk
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#define TERRAIN_GRID_FORMAT_VERSION 1
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#if TERRAIN_DEBUG
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#define ASSERT_RANGE(v,minv,maxv) assert((v)<=(maxv)&&(v)>=(minv))
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#else
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#define ASSERT_RANGE(v,minv,maxv)
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#endif
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/*
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Data conventions in this library:
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array[x][y]: x is increasing north, y is increasing east
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array[x]: low order bits increase east first
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bitmap: low order bits increase east first
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file: first entries increase east, then north
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*/
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class AP_Terrain
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{
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public:
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AP_Terrain(AP_AHRS &_ahrs, const AP_Mission &_mission, const AP_Rally &_rally);
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enum TerrainStatus {
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TerrainStatusDisabled = 0, // not enabled
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TerrainStatusUnhealthy = 1, // no terrain data for current location
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TerrainStatusOK = 2 // terrain data available
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};
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static const struct AP_Param::GroupInfo var_info[];
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// update terrain state. Should be called at 1Hz or more
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void update(void);
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// return status enum for health reporting
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enum TerrainStatus status(void);
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// send any pending terrain request message
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void send_request(mavlink_channel_t chan);
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// handle terrain data and reports from GCS
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void send_terrain_report(mavlink_channel_t chan, const Location &loc, bool extrapolate);
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void handle_data(mavlink_channel_t chan, mavlink_message_t *msg);
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void handle_terrain_check(mavlink_channel_t chan, mavlink_message_t *msg);
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void handle_terrain_data(mavlink_message_t *msg);
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// return terrain height in meters above sea level for a location
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// return false if not available
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bool height_amsl(const Location &loc, float &height);
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/*
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find difference between home terrain height and the terrain
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height at the current location in meters. A positive result
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means the terrain is higher than home.
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return false is terrain at the current location or at home
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location is not available
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If extrapolate is true then allow return of an extrapolated
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terrain altitude based on the last available data
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*/
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bool height_terrain_difference_home(float &terrain_difference,
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bool extrapolate = false);
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/*
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return estimated equivalent relative-to-home altitude in meters
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of a given height above the terrain at the current location
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This function allows existing height controllers which work on
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barometric altitude (relative to home) to be used with terrain
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based target altitude, by translating the "above terrain" altitude
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into an equivalent barometric relative height.
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return false if terrain data is not available either at the given
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location or at the home location.
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If extrapolate is true then allow return of an extrapolated
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terrain altitude based on the last available data
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*/
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bool height_relative_home_equivalent(float terrain_altitude,
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float &relative_altitude,
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bool extrapolate = false);
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/*
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return current height above terrain at current AHRS
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position.
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If extrapolate is true then extrapolate from most recently
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available terrain data is terrain data is not available for the
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current location.
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Return true if height is available, otherwise false.
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*/
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bool height_above_terrain(float &terrain_altitude, bool extrapolate = false);
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/*
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calculate lookahead rise in terrain. This returns extra altitude
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needed to clear upcoming terrain in meters
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*/
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float lookahead(float bearing, float distance, float climb_ratio);
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/*
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log terrain status to DataFlash
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*/
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void log_terrain_data(DataFlash_Class &dataflash);
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private:
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// allocate the terrain subsystem data
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void allocate(void);
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/*
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a grid block is a structure in a local file containing height
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information. Each grid block is 2048 in size, to keep file IO to
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block oriented SD cards efficient
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*/
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struct PACKED grid_block {
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// bitmap of 4x4 grids filled in from GCS (56 bits are used)
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uint64_t bitmap;
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// south west corner of block in degrees*10^7
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int32_t lat;
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int32_t lon;
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// crc of whole block, taken with crc=0
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uint16_t crc;
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// format version number
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uint16_t version;
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// grid spacing in meters
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uint16_t spacing;
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// heights in meters over a 32*28 grid
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int16_t height[TERRAIN_GRID_BLOCK_SIZE_X][TERRAIN_GRID_BLOCK_SIZE_Y];
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// indices info 32x28 grids for this degree reference
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uint16_t grid_idx_x;
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uint16_t grid_idx_y;
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// rounded latitude/longitude in degrees.
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int16_t lon_degrees;
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int8_t lat_degrees;
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};
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/*
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grid_block for disk IO, aligned on 2048 byte boundaries
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*/
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union grid_io_block {
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struct grid_block block;
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uint8_t buffer[2048];
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};
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enum GridCacheState {
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GRID_CACHE_INVALID=0, // when first initialised
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GRID_CACHE_DISKWAIT=1, // when waiting for disk read
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GRID_CACHE_VALID=2, // when at least partially valid
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GRID_CACHE_DIRTY=3 // when updates have been made, and
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// disk write needed
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};
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/*
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a grid_block plus some meta data used for requesting new blocks
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*/
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struct grid_cache {
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struct grid_block grid;
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volatile enum GridCacheState state;
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// the last time access was requested to this block, used for LRU
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uint32_t last_access_ms;
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};
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/*
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grid_info is a broken down representation of a Location, giving
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the index terms for finding the right grid
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*/
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struct grid_info {
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// rounded latitude/longitude in degrees.
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int8_t lat_degrees;
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int16_t lon_degrees;
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// lat and lon of SW corner of this 32*28 grid, *10^7 degrees
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int32_t grid_lat;
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int32_t grid_lon;
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// indices info 32x28 grids for this degree reference
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uint16_t grid_idx_x;
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uint16_t grid_idx_y;
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// indexes into 32x28 grid
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uint8_t idx_x; // north (0..27)
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uint8_t idx_y; // east (0..31)
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// fraction within the grid square
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float frac_x; // north (0..1)
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float frac_y; // east (0..1)
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// file offset of this grid
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uint32_t file_offset;
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};
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// given a location, fill a grid_info structure
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void calculate_grid_info(const Location &loc, struct grid_info &info) const;
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/*
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find a grid structure given a grid_info
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*/
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struct grid_cache &find_grid_cache(const struct grid_info &info);
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/*
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calculate bit number in grid_block bitmap. This corresponds to a
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bit representing a 4x4 mavlink transmitted block
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*/
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uint8_t grid_bitnum(uint8_t idx_x, uint8_t idx_y);
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/*
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given a grid_info check that a given idx_x/idx_y is available (set
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in the bitmap)
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*/
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bool check_bitmap(const struct grid_block &grid, uint8_t idx_x, uint8_t idx_y);
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/*
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request any missing 4x4 grids from a block
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*/
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bool request_missing(mavlink_channel_t chan, struct grid_cache &gcache);
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bool request_missing(mavlink_channel_t chan, const struct grid_info &info);
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/*
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look for blocks that need to be read/written to disk
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*/
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void schedule_disk_io(void);
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/*
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get some statistics for TERRAIN_REPORT
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*/
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uint8_t bitcount64(uint64_t b);
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void get_statistics(uint16_t &pending, uint16_t &loaded);
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/*
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disk IO functions
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*/
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int16_t find_io_idx(enum GridCacheState state);
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uint16_t get_block_crc(struct grid_block &block);
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void check_disk_read(void);
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void check_disk_write(void);
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void io_timer(void);
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void open_file(void);
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void seek_offset(void);
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void write_block(void);
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void read_block(void);
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/*
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check for missing mission terrain data
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*/
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void update_mission_data(void);
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/*
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check for missing rally data
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*/
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void update_rally_data(void);
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// parameters
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AP_Int8 enable;
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AP_Int16 grid_spacing; // meters between grid points
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// reference to AHRS, so we can ask for our position,
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// heading and speed
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AP_AHRS &ahrs;
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// reference to AP_Mission, so we can ask preload terrain data for
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// all waypoints
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const AP_Mission &mission;
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// reference to AP_Rally, so we can ask preload terrain data for
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// all rally points
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const AP_Rally &rally;
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// cache of grids in memory, LRU
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struct grid_cache cache[TERRAIN_GRID_BLOCK_CACHE_SIZE];
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// a grid_cache block waiting for disk IO
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enum DiskIoState {
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DiskIoIdle = 0,
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DiskIoWaitWrite = 1,
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DiskIoWaitRead = 2,
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DiskIoDoneRead = 3,
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DiskIoDoneWrite = 4
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};
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volatile enum DiskIoState disk_io_state;
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union grid_io_block disk_block;
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// last time we asked for more grids
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uint32_t last_request_time_ms;
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static const uint64_t bitmap_mask = (((uint64_t)1U)<<(TERRAIN_GRID_BLOCK_MUL_X*TERRAIN_GRID_BLOCK_MUL_Y)) - 1;
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// open file handle on degree file
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int fd;
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// has the timer been setup?
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bool timer_setup;
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// degrees lat and lon of file
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int8_t file_lat_degrees;
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int16_t file_lon_degrees;
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// do we have an IO failure
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volatile bool io_failure;
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// have we created the terrain directory?
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bool directory_created;
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// cache the home altitude, as it is needed so often
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float home_height;
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Location home_loc;
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// cache the last terrain height (AMSL) of the AHRS current
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// location. This is used for extrapolation when terrain data is
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// temporarily unavailable
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bool have_current_loc_height;
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float last_current_loc_height;
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// next mission command to check
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uint16_t next_mission_index;
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// next mission position to check
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uint8_t next_mission_pos;
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// last time the mission changed
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uint32_t last_mission_change_ms;
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// grid spacing during mission check
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uint16_t last_mission_spacing;
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// next rally command to check
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uint16_t next_rally_index;
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// last time the rally points changed
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uint32_t last_rally_change_ms;
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// grid spacing during rally check
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uint16_t last_rally_spacing;
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};
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#endif // AP_TERRAIN_AVAILABLE
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#endif // __AP_TERRAIN_H__
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