88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
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/*
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open source routing machine
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Copyright (C) Dennis Luxen, others 2010
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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 AFFERO 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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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 Affero General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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or see http://www.gnu.org/licenses/agpl.txt.
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** Interface to the GridSquares. Template parameter determines which kind of
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* raw data is used (NASA, or reduced). GridSquare data is globally cached, so
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* that many queries can be answered without having to constantly mmap & unmmap
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* the data files.
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*
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* Typical usage:
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*
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* Grid<NasaGridSquare> g();
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* cout << g.height(lng,lat) << endl;
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*
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*/
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#ifndef SRTMLOOKUP_H
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#define SRTMLOOKUP_H
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#include <cassert>
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#include <string>
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#include "NASAGridSquare.h"
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#include "../DataStructures/LRUCache.h"
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class SRTMLookup {
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public:
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SRTMLookup(std::string & _rp) : cache(MAX_CACHE_SIZE), ROOT_PATH(_rp) {
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// Double check that this compiler truncates towards zero.
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assert(-1 == int(float(-1.9)));
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}
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/** Returns the height above sea level for the given lat/lng. */
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short height(const float longitude, const float latitude) {
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if(0 == ROOT_PATH.size())
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return 0;
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int lng,lat;
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float lng_fraction,lat_fraction;
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split(longitude,lng,lng_fraction);
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split(latitude ,lat,lat_fraction);
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int k = key(lng,lat);
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if(!cache.Holds(k)) {
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cache.Insert(k , new NasaGridSquare(lng,lat, ROOT_PATH));
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}
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NasaGridSquare * result;
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cache.Fetch(k, result);
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return result->getHeight(lng_fraction,lat_fraction);
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}
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private:
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/** Split a floating point number (num) into integer (i) & fraction (f)
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* components. */
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inline void split(float num, int& i, float& f) const {
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if(num>=0.0)
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i=int(num);
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else
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i=int(num)-1;
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f=num-float(i);
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}
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/** Formula for grid squares' unique keys. */
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int key(int lng, int lat) {
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return 1000*lat + lng;
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}
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LRUCache<NasaGridSquare*> cache;
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static const int MAX_CACHE_SIZE = 250;
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std::string ROOT_PATH;
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};
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#endif // SRTMLOOKUP_H
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