i86/elks/elkscmd/mtools/convdate.c

   1 /*
   2  * convdate(), convtime(), convstamp()
   3  */
   4 #include <stdio.h>
   5 /*
   6  * convert MSDOS directory datestamp to ASCII.
   7  */
   8
   9 char *
  10 convdate(date_high, date_low)
  11 unsigned date_high, date_low;
  12 {
  13 /*
  14  *          hi byte     |    low byte
  15  *      |7|6|5|4|3|2|1|0|7|6|5|4|3|2|1|0|
  16  *      | | | | | | | | | | | | | | | | |
  17  *      \   7 bits    /\4 bits/\ 5 bits /
  18  *         year +80      month     day
  19  */
  20         static char ans[9];
  21         unsigned char year, month_hi, month_low, day;
  22
  23         year = (date_high >> 1) + 80;
  24         month_hi = (date_high & 0x1) << 3;
  25         month_low = date_low >> 5;
  26         day = date_low & 0x1f;
  27         sprintf(ans, "%2d-%02d-%02d", month_hi+month_low, day, year);
  28         return(ans);
  29 }
  30
  31 /*
  32  * Convert MSDOS directory timestamp to ASCII.
  33  */
  34
  35 char *
  36 convtime(time_high, time_low)
  37 unsigned time_high, time_low;
  38 {
  39 /*
  40  *          hi byte     |    low byte
  41  *      |7|6|5|4|3|2|1|0|7|6|5|4|3|2|1|0|
  42  *      | | | | | | | | | | | | | | | | |
  43  *      \  5 bits /\  6 bits  /\ 5 bits /
  44  *         hour      minutes     sec*2
  45  */
  46         static char ans[7];
  47         char am_pm;
  48         unsigned char hour, min_hi, min_low;
  49
  50         hour = time_high >> 3;
  51         am_pm = (hour >= 12) ? 'p' : 'a';
  52         if (hour > 12)
  53                 hour = hour -12;
  54         if (hour == 0)
  55                 hour = 12;
  56         min_hi = (time_high & 0x7) << 3;
  57         min_low = time_low >> 5;
  58         sprintf(ans, "%2d:%02d%c", hour, min_hi+min_low, am_pm);
  59         return(ans);
  60 }
  61
  62 /*
  63  * Convert a MSDOS time & date stamp to the Unix time() format
  64  */
  65
  66 long
  67 convstamp(time_field, date_field)
  68 unsigned char *time_field, *date_field;
  69 {
  70         extern long timezone;
  71         int year, mon, mday, hour, min, sec, old_leaps;
  72         long answer, sec_year, sec_mon, sec_mday, sec_hour, sec_min, sec_leap;
  73         static int month[] = {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304,
  74         334};
  75                                         /* disect the parts */
  76         year = (date_field[1] >> 1) + 1980;
  77         mon = (((date_field[1] & 0x1) << 3) + (date_field[0] >> 5));
  78         mday = date_field[0] & 0x1f;
  79         hour = time_field[1] >> 3;
  80         min = (((time_field[1] & 0x7) << 3) + (time_field[0] >> 5));
  81         sec = (time_field[0] & 0x1f) * 2;
  82                                         /* how many previous leap years */
  83         old_leaps = (year -1972) / 4;
  84         sec_leap = old_leaps * 24 * 60 * 60;
  85                                         /* back off 1 day if before 29 Feb */
  86         if (!(year % 4) && mon < 3)
  87                 sec_leap -= 24 * 60 * 60;
  88         sec_year = (year - 1970) * 365 * 24 * 60 * 60;
  89         sec_mon = month[mon -1] * 24 * 60 * 60;
  90         sec_mday = mday * 24 * 60 * 60;
  91         sec_hour = hour * 60 * 60;
  92         sec_min = min * 60;
  93
  94         answer = sec_leap + sec_year + sec_mon + sec_mday + sec_hour + sec_min + sec/* + timezone*/;
  95         return(answer);
  96 }