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GARS.cpp
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/**
* \file GARS.cpp
* \brief Implementation for GeographicLib::GARS class
*
* Copyright (c) Charles Karney (2015-2022) <karney@alum.mit.edu> and licensed
* under the MIT/X11 License. For more information, see
* https://geographiclib.sourceforge.io/
**********************************************************************/
#include <GeographicLib/GARS.hpp>
#include <GeographicLib/Utility.hpp>
namespace GeographicLib {
using namespace std;
const char* const GARS::digits_ = "0123456789";
const char* const GARS::letters_ = "ABCDEFGHJKLMNPQRSTUVWXYZ";
void GARS::Forward(real lat, real lon, int prec, string& gars) {
using std::isnan; // Needed for Centos 7, ubuntu 14
if (fabs(lat) > Math::qd)
throw GeographicErr("Latitude " + Utility::str(lat)
+ "d not in [-" + to_string(Math::qd)
+ "d, " + to_string(Math::qd) + "d]");
if (isnan(lat) || isnan(lon)) {
gars = "INVALID";
return;
}
lon = Math::AngNormalize(lon);
if (lon == Math::hd) lon = -Math::hd; // lon now in [-180,180)
if (lat == Math::qd) lat *= (1 - numeric_limits<real>::epsilon() / 2);
prec = max(0, min(int(maxprec_), prec));
int
x = int(floor(lon * m_)) - lonorig_ * m_,
y = int(floor(lat * m_)) - latorig_ * m_,
ilon = x * mult1_ / m_,
ilat = y * mult1_ / m_;
x -= ilon * m_ / mult1_; y -= ilat * m_ / mult1_;
char gars1[maxlen_];
++ilon;
for (int c = lonlen_; c--;) {
gars1[c] = digits_[ ilon % baselon_]; ilon /= baselon_;
}
for (int c = latlen_; c--;) {
gars1[lonlen_ + c] = letters_[ilat % baselat_]; ilat /= baselat_;
}
if (prec > 0) {
ilon = x / mult3_; ilat = y / mult3_;
gars1[baselen_] = digits_[mult2_ * (mult2_ - 1 - ilat) + ilon + 1];
if (prec > 1) {
ilon = x % mult3_; ilat = y % mult3_;
gars1[baselen_ + 1] = digits_[mult3_ * (mult3_ - 1 - ilat) + ilon + 1];
}
}
gars.resize(baselen_ + prec);
copy(gars1, gars1 + baselen_ + prec, gars.begin());
}
void GARS::Reverse(const string& gars, real& lat, real& lon,
int& prec, bool centerp) {
int len = int(gars.length());
if (len >= 3 &&
toupper(gars[0]) == 'I' &&
toupper(gars[1]) == 'N' &&
toupper(gars[2]) == 'V') {
lat = lon = Math::NaN();
return;
}
if (len < baselen_)
throw GeographicErr("GARS must have at least 5 characters " + gars);
if (len > maxlen_)
throw GeographicErr("GARS can have at most 7 characters " + gars);
int prec1 = len - baselen_;
int ilon = 0;
for (int c = 0; c < lonlen_; ++c) {
int k = Utility::lookup(digits_, gars[c]);
if (k < 0)
throw GeographicErr("GARS must start with 3 digits " + gars);
ilon = ilon * baselon_ + k;
}
if (!(ilon >= 1 && ilon <= 2 * Math::td))
throw GeographicErr("Initial digits in GARS must lie in [1, 720] " +
gars);
--ilon;
int ilat = 0;
for (int c = 0; c < latlen_; ++c) {
int k = Utility::lookup(letters_, gars[lonlen_ + c]);
if (k < 0)
throw GeographicErr("Illegal letters in GARS " + gars.substr(3,2));
ilat = ilat * baselat_ + k;
}
if (!(ilat < Math::td))
throw GeographicErr("GARS letters must lie in [AA, QZ] " + gars);
real
unit = mult1_,
lat1 = ilat + latorig_ * unit,
lon1 = ilon + lonorig_ * unit;
if (prec1 > 0) {
int k = Utility::lookup(digits_, gars[baselen_]);
if (!(k >= 1 && k <= mult2_ * mult2_))
throw GeographicErr("6th character in GARS must [1, 4] " + gars);
--k;
unit *= mult2_;
lat1 = mult2_ * lat1 + (mult2_ - 1 - k / mult2_);
lon1 = mult2_ * lon1 + (k % mult2_);
if (prec1 > 1) {
k = Utility::lookup(digits_, gars[baselen_ + 1]);
if (!(k >= 1 /* && k <= mult3_ * mult3_ */))
throw GeographicErr("7th character in GARS must [1, 9] " + gars);
--k;
unit *= mult3_;
lat1 = mult3_ * lat1 + (mult3_ - 1 - k / mult3_);
lon1 = mult3_ * lon1 + (k % mult3_);
}
}
if (centerp) {
unit *= 2; lat1 = 2 * lat1 + 1; lon1 = 2 * lon1 + 1;
}
lat = lat1 / unit;
lon = lon1 / unit;
prec = prec1;
}
} // namespace GeographicLib
GARS.hpp
Header for GeographicLib::GARS class.
Utility.hpp
Header for GeographicLib::Utility class.
GeographicLib::GARS::Reverse
static void Reverse(const std::string &gars, real &lat, real &lon, int &prec, bool centerp=true)
Definition GARS.cpp:60
GeographicLib::GARS::Forward
static void Forward(real lat, real lon, int prec, std::string &gars)
Definition GARS.cpp:20
GeographicLib::GeographicErr
Exception handling for GeographicLib.
Definition Constants.hpp:316
GeographicLib::Math::qd
static constexpr int qd
degrees per quarter turn
Definition Math.hpp:145
GeographicLib::Math::AngNormalize
static T AngNormalize(T x)
Definition Math.cpp:66
GeographicLib::Math::td
static constexpr int td
degrees per turn
Definition Math.hpp:149
GeographicLib::Math::NaN
static T NaN()
Definition Math.cpp:277
GeographicLib::Math::hd
static constexpr int hd
degrees per half turn
Definition Math.hpp:148
GeographicLib::Utility::lookup
static int lookup(const std::string &s, char c)
Definition Utility.cpp:160
GeographicLib::Utility::str
static std::string str(T x, int p=-1)
Definition Utility.hpp:161
GeographicLib
Namespace for GeographicLib.
Definition Accumulator.cpp:12
std
Definition NearestNeighbor.hpp:806