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Support for converting unix timestamp to the Solar Hijri calendar is added. This is an early implementation that needs to be carefully tested and if everything goes well, I will release a version containing the same arithmetic for all calendar/timezone pairs. The code is in currently in add_timestamp branch.

Please test this feature as far as you can. Following is a simple test program to validate any input data.

#include <stdio.h>
#include <stdint.h>
#include <libcalendars/cl-solar-hijri.h>
#include <libcalendars/cl-gregorian.h>

int main() {
    time_t ts[] = {1421107199, 1521318959, 1508592260,
                   1521307799, 1521307800
                  };
    for(size_t i = 0; i < (sizeof(ts) / sizeof(ts[0])); ++i) {
        int16_t jy;
        uint8_t jm;
        uint16_t jd;
        uint8_t h;
        uint8_t m;
        uint8_t s;
        ts_to_sh(ts[i], 12600, &jy, &jm, &jd, &h, &m, &s);
        struct tm* gm = gmtime(&ts[i]);
        printf("%ld = %02d/%02d/%02d %02d:%02d:%02d %hu/%02d/%02d %02d:%02d:%02d\n", ts[i],
               gm->tm_year+1900,
               gm->tm_mon+1,
               gm->tm_mday+1,
               gm->tm_hour,
               gm->tm_min,
               gm->tm_sec,
               jy, jm, jd, h, m, s);
    }
    return 0;
}

which results in:

1421107199 = 2015/01/13 23:59:59 1393/10/23 03:29:59
1521318959 = 2018/03/18 20:35:59 1396/12/27 00:05:59
1508592260 = 2017/10/22 13:24:20 1396/07/29 16:54:20
1521307799 = 2018/03/18 17:29:59 1396/12/26 20:59:59
1521307800 = 2018/03/18 17:30:00 1396/12/26 21:00:00

The official calendar in Iran is an unknown combination of Birashk's method and 33-years algorithm, with some exceptions added. These exceptions are not handled in this library, so retrospectively speaking, there will be +-1 day shifts in JDN calculations for some years before 1375.

For future year numbers, there is no known calendar release or schedule ahead of the time, so we will have no means to calculate day shift for them.

Hi
I tried to compile branch add_timestamp and it seams cl-tz.h is missing.

Steps to reproduce

Just use the lib as normal way with the following script:

#include <libcalendars/cl-solar-hijri.h>

#define IRAN_TIME_ZONE_DIFF 12600U // UTC + 03:30(12600s)

float toJD(uint32_t epoch) {
  return (epoch / 86400.0) + 2440587.5;
}

int main(int argc, char *argv[]) {
  uint32_t epoch = 1521318959U; // 20:35:59 PM
  uint32_t JD = toJD(epoch + IRAN_TIME_ZONE_DIFF); // 00:05:59 AM
  int16_t jy;
  uint8_t jm;
  uint16_t jd;
  jdn_to_sh(JD, &jy, &jm, &jd);
  printf("\n Jalali: %d/%d/%d\n", jy, jm, jd);
  system("pause");
  return 0;
}

Expected behaviour

We're 359 second(00:05:59) past the 1396/12/26 and we expect to see 1396/12/27

Actual behaviour

The jdn_to_sh(...) calculate date as 1396/12/26

Configuration

Operating system: Microsoft Windows 10(build 16299.309)
Compiler: MSVC2015(14.0)
Version of libcalendars: latest git version

Regards.
IMAN.