ardupilot/libraries/AP_OLC/AP_OLC.h

72 lines
2.5 KiB
C++

/*
* This file is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This file is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*
* AP_OLC is based on INAV olc.c implemention, thanks @fiam and other contributors.
*/
#pragma once
#include <stdint.h>
#include <AP_HAL/AP_HAL.h>
#include <AP_HAL/AP_HAL_Boards.h>
#ifndef HAL_PLUSCODE_ENABLE
#define HAL_PLUSCODE_ENABLE !HAL_MINIMIZE_FEATURES && BOARD_FLASH_SIZE > 1024
#endif
#if HAL_PLUSCODE_ENABLE
class AP_OLC
{
public:
// olc_encodes the given coordinates in lat and lon (deg * OLC_DEG_MULTIPLIER)
// as an OLC code of the given length. It returns the number of characters
// written to buf.
static int olc_encode(int32_t lat, int32_t lon, size_t length, char *buf, size_t bufsize);
private:
static constexpr uint8_t SEPARATOR_CHAR = '+';
static constexpr uint8_t SEPARATOR_POS = 8;
static constexpr uint8_t PADDING_CHAR = '0';
static constexpr uint8_t ENCODING_BASE = 20;
static constexpr uint8_t PAIR_CODE_LEN = 10;
static constexpr uint8_t CODE_LEN_MAX = 15;
static constexpr uint8_t GRID_COLS = 4;
static constexpr uint8_t GRID_ROWS = ENCODING_BASE / GRID_COLS;
static constexpr int32_t OLC_DEG_MULTIPLIER = 10000000; // 1e7
static constexpr int32_t LAT_MAX = 90 * OLC_DEG_MULTIPLIER;
static constexpr int32_t LON_MAX = 180 * OLC_DEG_MULTIPLIER;
static const int32_t initial_exponent;
// Work out the enclosing resolution (in degrees) for the grid algorithm.
static const int32_t grid_size;
// Work out the initial resolution
static const int32_t initial_resolution;
static constexpr char olc_alphabet[] = "23456789CFGHJMPQRVWX";
static float compute_precision_for_length(int length);
static int32_t adjust_latitude(int32_t lat, size_t code_len);
static int32_t normalize_longitude(int32_t lon);
static unsigned encode_pairs(uint32_t lat, uint32_t lon, size_t length, char *buf, size_t bufsize);
static int encode_grid(uint32_t lat, uint32_t lon, size_t length, char *buf, size_t bufsize);
};
#endif