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Use constant Julian start day #79

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Use constant Julian start day #79

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5 changes: 4 additions & 1 deletion src/defs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
#define e6a 1.0E-6
#define tothrd 6.6666666666666666E-1 /* 2/3 */
#define xj2 1.0826158E-3 /* J2 Harmonic (WGS '72) */
#define xj3 -2.53881E-6 /* J3 Harmonic (WGS '72) */
#define xj3 -2.53881E-6 /* J3 Harmonic (WGS '72) */
#define xj4 -1.65597E-6 /* J4 Harmonic (WGS '72) */
#define xke 7.43669161E-2
#define xkmper 6.378137E3 /* WGS 84 Earth radius km */
Expand Down Expand Up @@ -60,5 +60,8 @@
/* doppler calculation */
#define SPEED_OF_LIGHT 299792458.0

/* Date/Time constants */
#define JULIAN_START_DAY 315446400


#endif
15 changes: 4 additions & 11 deletions src/julian_date.c
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
#define _POSIX_C_SOURCE 1
#include <predict/predict.h>
#include "defs.h"
#include <stdio.h>


Expand Down Expand Up @@ -48,15 +49,7 @@ time_t mktime_utc(const struct tm* timeinfo_utc)
**/
time_t get_julian_start_day()
{
struct tm start_time;
start_time.tm_sec = 0;
start_time.tm_min = 0;
start_time.tm_hour = 0;
start_time.tm_mday = 31;
start_time.tm_mon = 11;
start_time.tm_year = 1979-1900;
start_time.tm_isdst = 0;
return mktime_utc(&start_time);
return JULIAN_START_DAY;
}

#define NUM_SECONDS_IN_DAY (24.0*60.0*60.0)
Expand All @@ -71,10 +64,10 @@ time_t predict_from_julian(predict_julian_date_t date)
{
double seconds_since = date*NUM_SECONDS_IN_DAY;
time_t ret_time = get_julian_start_day();

//add number of seconds since julian start day to the julian start day, get current time_t
struct tm timeinfo;
gmtime_r(&ret_time, &timeinfo);
gmtime_r(&ret_time, &timeinfo);
timeinfo.tm_sec += seconds_since;
ret_time = mktime_utc(&timeinfo);
return ret_time;
Expand Down