NASA Ocean Color

ocssw V2022

 #define LEAPSEC_DAT "leapsec.dat"
 #define JD_1993 2448988.5
 #define SECONDS_IN_DAY 86400
 #define MAX_LEAP_SECONDS 32
 #define UNIX_TIME_AT_1993 725846400.0
  
 static double leap_seconds_tai93[MAX_LEAP_SECONDS] = {0};
 static double leap_seconds_unix[MAX_LEAP_SECONDS] = {0};
  
 #include <timeutils.h>
 #include <stdlib.h>
 #include <stdio.h>
  
 void init_leapsecond_arrays() {
     char *varRoot;
     char leapsecdat[FILENAME_MAX];
  
     if (!leap_seconds_tai93[0]) {
         if ((varRoot = getenv("OCVARROOT")) == NULL) {
             printf("-E- OCVARROOT environment variable is not defined.\n");
             exit(EXIT_FAILURE);
         }
         snprintf(leapsecdat, FILENAME_MAX, "%s/common/tai-utc.dat", varRoot);
         FILE *file_h = fopen(leapsecdat, "rb");
         if (file_h == NULL) {
             snprintf(leapsecdat, FILENAME_MAX, "%s/viirsn/IETTime.dat", varRoot);
             file_h = fopen(leapsecdat, "rb");
             if (file_h == NULL) {
                 snprintf(leapsecdat, FILENAME_MAX, "%s/modis/leapsec.dat", varRoot);
                 file_h = fopen(leapsecdat, "rb");
                 if (file_h == NULL) {
                     printf("-E- %s:%d - leap second file (%s/common/tai-utc.dat) not found.\n", __FILE__, __LINE__, varRoot);
                     exit(EXIT_FAILURE);
                 }
             }
         }
         int i = 0, year;
         float jd;
         while (fgetc(file_h) != '\n')
             ;
         while (fscanf(file_h, " %d %*s %*d =JD %f%*[^\n]", &year, &jd) == 2) {
             if (year >= 1993) {
                 leap_seconds_tai93[i] = ((jd - JD_1993) * SECONDS_IN_DAY) + i;
                 leap_seconds_unix[i] =  ((jd - JD_1993) * SECONDS_IN_DAY) + UNIX_TIME_AT_1993;
                 i++;
                 if (i >= MAX_LEAP_SECONDS) {
                     printf("-E- %s:%d - max leap seconds reached in %s\n", __FILE__, __LINE__, leapsecdat);
                     exit(EXIT_FAILURE);
                 }
             }
         }
         fclose(file_h);
     }
     
 }
  
  
 int leapseconds_since_1993(double tai93time) {
  
     init_leapsecond_arrays();
  
     int i;
     for (i = 0; i < MAX_LEAP_SECONDS - 1 && leap_seconds_tai93[i]; i++) {
         if (tai93time < leap_seconds_tai93[i]) {
             return i;
         }
     }
     return i;
 }
  
 int leapseconds_since_1993_unix(double unixtime) {
  
     init_leapsecond_arrays();
  
     int i;
     for (i = 0; i < MAX_LEAP_SECONDS - 1 && leap_seconds_unix[i]; i++) {
         if (unixtime < leap_seconds_unix[i]) {
             return i;
         }
     }
     return i;
 }