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sunrise/sunset: fix for ambiguous error value

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sunset = 0 is a valid result, as the function result is in UTC and not local time .
Example: local time is UTC-8, local sunrise = 08:00am => getSunriseUTC()  = 0.

So we cannot use "0" for "invalid". Using UINT16_MAX resolves the problem, and even allows to simplify calculateSunriseAndSunset() a bit.
This commit is contained in:
Frank 2023-12-23 13:13:10 +01:00
parent 5ab012163e
commit 72e864b013
1 changed files with 11 additions and 10 deletions
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21
wled00/ntp.cpp
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@ -447,7 +447,7 @@ void checkTimers()
}
#define ZENITH -0.83
// get sunrise (or sunset) time (in minutes) for a given day at a given geo location
// get sunrise (or sunset) time (in minutes) for a given day at a given geo location. Returns >= INT16_MAX in case of "no sunset"
static int getSunriseUTC(int year, int month, int day, float lat, float lon, bool sunset=false) {
//1. first calculate the day of the year
float N1 = 275 * month / 9;
@ -482,8 +482,8 @@ static int getSunriseUTC(int year, int month, int day, float lat, float lon, boo
//7a. calculate the Sun's local hour angle
float cosH = (sinf(DEG_TO_RAD*ZENITH) - (sinDec * sinf(DEG_TO_RAD*lat))) / (cosDec * cosf(DEG_TO_RAD*lat));
if ((cosH > 1.0f) && !sunset) return 0; // the sun never rises on this location (on the specified date)
if ((cosH < -1.0f) && sunset) return 0; // the sun never sets on this location (on the specified date)
if ((cosH > 1.0f) && !sunset) return INT16_MAX; // the sun never rises on this location (on the specified date)
if ((cosH < -1.0f) && sunset) return INT16_MAX; // the sun never sets on this location (on the specified date)
//7b. finish calculating H and convert into hours
float H = sunset ? RAD_TO_DEG*acosf(cosH) : 360 - RAD_TO_DEG*acosf(cosH);
@ -499,6 +499,7 @@ static int getSunriseUTC(int year, int month, int day, float lat, float lon, boo
return UT*60;
}
#define SUNSET_MAX (24*60) // 1day = max expected absolute value for sun offset in minutes
// calculate sunrise and sunset (if longitude and latitude are set)
void calculateSunriseAndSunset() {
if ((int)(longitude*10.) || (int)(latitude*10.)) {
@ -509,9 +510,9 @@ void calculateSunriseAndSunset() {
tim_0.tm_sec = 0;
tim_0.tm_isdst = 0;
// Due to math instability, its possible to get a bad sunrise/sunset = 00:00 (see issue #3601)
// So in case we get 00:00, try to use the sunset/sunrise of previous day. Max 3 days back, this worked well in all cases I tried.
// When latitude = 66,6 (N or S), the functions sometimes returns 2147483647, so "unexpected large" is another condition for retry
// Due to limited accuracy, its possible to get a bad sunrise/sunset displayed as "00:00" (see issue #3601)
// So in case of invalid result, we try to use the sunset/sunrise of previous day. Max 3 days back, this worked well in all cases I tried.
// When latitude = 66,6 (N or S), the functions sometimes returns 2147483647, so this "unexpected large" is another condition for retry
int minUTC = 0;
int retryCount = 0;
do {
@ -519,9 +520,9 @@ void calculateSunriseAndSunset() {
minUTC = getSunriseUTC(year(theDay), month(theDay), day(theDay), latitude, longitude, false);
DEBUG_PRINT(F("* sunrise (minutes from UTC) = ")); DEBUG_PRINTLN(minUTC);
retryCount ++;
} while ((minUTC == 0 || abs(minUTC) > 2*24*60) && (retryCount <= 3));
} while ((abs(minUTC) > SUNSET_MAX) && (retryCount <= 3));
if (minUTC) {
if (abs(minUTC) <= SUNSET_MAX) {
// there is a sunrise
if (minUTC < 0) minUTC += 24*60; // add a day if negative
tim_0.tm_hour = minUTC / 60;
@ -538,9 +539,9 @@ void calculateSunriseAndSunset() {
minUTC = getSunriseUTC(year(theDay), month(theDay), day(theDay), latitude, longitude, true);
DEBUG_PRINT(F("* sunset (minutes from UTC) = ")); DEBUG_PRINTLN(minUTC);
retryCount ++;
} while ((minUTC == 0 || abs(minUTC) > 2*24*60) && (retryCount <= 3));
} while ((abs(minUTC) > SUNSET_MAX) && (retryCount <= 3));
if (minUTC) {
if (abs(minUTC) <= SUNSET_MAX) {
// there is a sunset
if (minUTC < 0) minUTC += 24*60; // add a day if negative
tim_0.tm_hour = minUTC / 60;