compilers/linux86-0.16.17/libc/msdos/time.c

   1
   2 #include <time.h>
   3
   4 static int mdays[13] = { 0,31,31+28,31+28+31,31+28+31+30,
   5         31+28+31+30+31,31+28+31+30+31+30,31+28+31+30+31+30+31,
   6         31+28+31+30+31+30+31+31,31+28+31+30+31+30+31+31+30,
   7         31+28+31+30+31+30+31+31+30+31,31+28+31+30+31+30+31+31+30+31+30,
   8         365 };
   9
  10 #define SECSPERHOUR     (60*60)
  11 #define SECSPERDAY      (SECSPERHOUR*24L)
  12
  13 /****************************************
  14  * Return the number of seconds that have elapsed since the start
  15  * of 1970.
  16  * Input:
  17  *      timer   pointer to where to store result (or NULL)
  18  * Output:
  19  *      *timer = result (unless timer == NULL)
  20  * Returns:
  21  *      time
  22  */
  23
  24 static long get_time(ah)
  25 {
  26 #asm
  27 #if !__FIRST_ARG_IN_AX__
  28   mov   bx,sp
  29   mov   ax,[bx+2]
  30 #endif
  31   mov   ah,al
  32   int   $21
  33   mov   ax,dx
  34   mov   dx,cx
  35 #endasm
  36 }
  37
  38 time_t time(timer)
  39 time_t *timer;
  40 {
  41   unsigned day,month,year;
  42   long rv;
  43   time_t t;
  44
  45   rv = get_time(0x2C);
  46   rv >>= 8; t = (rv & 0xFF);
  47   rv >>= 8; t += (rv & 0xFF)*60;
  48   rv >>= 8; t += (rv & 0xFF)*3600;
  49
  50   rv = get_time(0x2A);
  51   day = (rv & 0xFF);
  52   rv >>= 8; month = (rv & 0xFF) -1;
  53   rv >>= 8; year = (rv & 0xFFFF) - 1970;
  54
  55   if (month <= 1 || year & 3)   /* if before Feb or not a leap year     */
  56         day--;                  /* don't add day for this leap year     */
  57   day += mdays[month];          /* day in year                          */
  58   day += (year + 3) >> 2;       /* add a day for each leap year, but    */
  59                                 /* don't worry about 2100               */
  60   t += ((year * 365L) + day) * SECSPERDAY;
  61   if (timer)
  62         *timer = t;
  63   return t;
  64 }