src/runtime/time.c

   1 /*
   2  * time support routines that are easier to do in C than in Lisp
   3  */
   4
   5 /*
   6  * This software is part of the SBCL system. See the README file for
   7  * more information.
   8  *
   9  * This software is derived from the CMU CL system, which was
  10  * written at Carnegie Mellon University and released into the
  11  * public domain. The software is in the public domain and is
  12  * provided with absolutely no warranty. See the COPYING and CREDITS
  13  * files for more information.
  14  */
  15
  16 #include <stdio.h>
  17 #include <time.h>
  18 #include "runtime.h"
  19
  20 void get_timezone(time_t when, int *secwest, boolean *dst)
  21 {
  22     struct tm ltm, gtm;
  23     int sw;
  24
  25     ltm = *localtime(&when);
  26     gtm = *gmtime(&when);
  27
  28     sw = (((gtm.tm_hour*60)+gtm.tm_min)*60+gtm.tm_sec) - (((ltm.tm_hour*60)+ltm.tm_min)*60+ltm.tm_sec);
  29     if ((gtm.tm_wday + 1) % 7 == ltm.tm_wday)
  30         sw -= 24*3600;
  31     else if (gtm.tm_wday == (ltm.tm_wday + 1) % 7)
  32         sw += 24*3600;
  33     *secwest = sw;
  34     *dst = ltm.tm_isdst;
  35 }