apps/lib/stdlibc/sys_time.c

   1 /*
   2     meinOS - A unix-like x86 microkernel operating system
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU Lesser General Public License as published by
   7     the Free Software Foundation, either version 3 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include <sys/time.h>
  20 #include <time.h>
  21 #include <cmos.h>
  22
  23 static time_t start_time = 0;
  24 static clock_t start_ticks;
  25
  26 /**
  27  * Checks whether year is a leap year
  28  *  @param year Year to check
  29  *  @return If year is a leap year
  30  */
  31 static int is_leapyear(unsigned int year) {
  32   if (year%400==0) return 1;
  33   else if (year%100==0) return 0;
  34   else if (year%4==0) return 1;
  35   else return 0;
  36 }
  37
  38 /**
  39  * Gets yday
  40  *  @param tm tm to get yday for
  41  */
  42 static void getyday(struct tm *tm) {
  43   unsigned int mdays[12] = {
  44     31,
  45     31+28,
  46     31+28+31,
  47     31+28+31+30,
  48     31+28+31+30+31,
  49     31+28+31+30+31+30,
  50     31+28+31+30+31+30+31,
  51     31+28+31+30+31+30+31+31,
  52     31+28+31+30+31+30+31+31+30,
  53     31+28+31+30+31+30+31+31+30+31,
  54     31+28+31+30+31+30+31+31+30+31+30,
  55     31+28+31+30+31+30+31+31+30+31+30+31
  56   };
  57
  58   tm->tm_yday = (tm->tm_mon>0?mdays[tm->tm_mon-1]:0)+tm->tm_mday;
  59   if (is_leapyear(tm->tm_year+1900)) tm->tm_yday++;
  60 }
  61
  62 /**
  63  * Gets mday
  64  *  @param tm tm to get mday for
  65  */
  66 static void getwday(struct tm *tm) {
  67   unsigned int doomsdays[] = {1,6,4,2};
  68   unsigned int year = tm->tm_year+1900;
  69   unsigned int dday_idx = (year/100)%4;
  70   unsigned int step1 = (year%100)/12;
  71   unsigned int step2 = (year%100)%12;
  72   unsigned int step3 = step2/4;
  73   unsigned int dday_year = (doomsdays[dday_idx]+((step1+step2+step3)%7))%7;
  74   unsigned int january0 = dday_year+(7-((59+is_leapyear(year)?1:0)%7));
  75   tm->tm_wday = ((january0+(tm->tm_yday%7))%7)-1;
  76 }
  77
  78 /**
  79  * Gets the date and time
  80  *  @param tp Time pointer
  81  *  @return Success?
  82  */
  83 int gettimeofday(struct timeval *tp,void *tzp) {
  84   if (start_time==0) {
  85     struct tm tm = {
  86       .tm_sec = cmos_getsecond(),
  87       .tm_min = cmos_getminute(),
  88       .tm_hour = cmos_gethour(),
  89       .tm_mday = cmos_getday(),
  90       .tm_mon = cmos_getmonth()-1,
  91       .tm_year = cmos_getyear()-1900
  92     };
  93     getyday(&tm);
  94     getwday(&tm);
  95
  96     start_time = mktime(&tm);
  97     start_ticks = clock();
  98   }
  99
 100   tp->tv_sec  = start_time+(clock()-start_ticks)/CLOCKS_PER_SEC;
 101   tp->tv_usec = ((clock()-start_ticks)*1000000/CLOCKS_PER_SEC)%1000000;
 102
 103   return 0;
 104 }