Implementing a workaround for Mingw bug 2152 and better documentation for the Sun class

meteoio/Date.cc

@@ -30,6 +30,20 @@ using namespace std;
 
 namespace mio {
 
+#ifdef MINGW
+	//some version of MINGW have a buggy 64 bits implementation of difftime
+	//this is Mingw bug 2152
+	static __inline__
+	double difftime( time_t __t1, time_t __t0 ) {
+		if (sizeof(time_t)==8) { //time_t is 64 bits
+			return (double)((long double)(__t1) - (long double)(__t0));
+		} else {
+			//return (double)((__int64)(__t1) - (__int64)(__t0));
+			return (double)__t1 - (double)__t0;
+		}
+	}
+#endif
+
 const int Date::daysLeapYear[12] = {31,29,31,30,31,30,31,31,30,31,30,31};
 const int Date::daysNonLeapYear[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
 const double Date::DST_shift = 1.0; //in hours
@@ -105,15 +119,14 @@ void Date::setUndef(const bool& flag) {
 * @brief Set internal gmt time from system time as well as system time zone.
 */
 void Date::setFromSys() {
-	/*const time_t curr = time(NULL); //current time in UTC
-	tm local = *localtime(&curr); //convert to local time
-	const double tz = (double)local.tm_gmtoff/3600.; //time zone shift*/
-
 	const time_t curr = time(NULL);// current time in UTC
 	tm local = *gmtime(&curr);// current time in UTC, stored as tm
-	const time_t utc = (mktime(&local));// convert GMT tm to GMT time_t
+	const time_t utc = mktime(&local);// convert GMT tm to GMT time_t
+#ifndef MINGW
 	double tz = - difftime(utc,curr)/3600.; //time zone shift (sign so that if curr>utc, tz>0)
-
+#else //workaround for Mingw bug 2152
+	double tz = - mio::difftime(utc,curr)/3600.; //time zone shift (sign so that if curr>utc, tz>0)
+#endif
 	setDate( curr ); //Unix time_t setter, always in gmt
 	setTimeZone( tz );
 }

meteoio/meteolaws/Sun.cc

@@ -137,7 +137,7 @@ void SunObject::getClearSky(const double& sun_elevation, const double& R_toa,
                             const double& ta, const double& rh, const double& pressure, const double& ground_albedo,
                             double& R_direct, double& R_diffuse) const
 {
-	//these pow cost us a lot here, but replacing them by fastPow() has a large impact o accuracy (because of the exp())
+	//these pow cost us a lot here, but replacing them by fastPow() has a large impact on accuracy (because of the exp())
 	const double olt = 0.32;   //ozone layer thickness (cm) U.S.standard = 0.34 cm
 	const double w0 = 0.9;     //fraction of energy scattered to total attenuation by aerosols (Bird and Hulstrom(1981))
 	const double fc = 0.84;    //fraction of forward scattering to total scattering (Bird and Hulstrom(1981))

meteoio/meteolaws/Sun.h

@@ -30,8 +30,10 @@ namespace mio {
 
 /**
  * @class SunObject
- * @brief A class to calculate Sun's characteristics
- *
+ * @brief A class to calculate Solar radiation characteristics
+ * This is largely based on M. Iqbal, <i>"An introduction to solar radiation"</i>, 1983, Academic Press,  ISBN: 0-12-373750-8.
+ * The Sun's position is provided by the SunTrajectory class (currently the only implemented algorithm is Meeus).
+ * All units are SI. See http://www.meteoexploration.com/products/solarcalc.php for a validation calculator.
  * @ingroup meteolaws
  * @author Mathias Bavay
  * @date   2010-06-10