diff options
Diffstat (limited to 'linux/kernel/mktime.c')
| -rw-r--r-- | linux/kernel/mktime.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/linux/kernel/mktime.c b/linux/kernel/mktime.c new file mode 100644 index 0000000..3ba79be --- /dev/null +++ b/linux/kernel/mktime.c @@ -0,0 +1,52 @@ +#include <time.h> + +/* + * This isn't the library routine, it is only used in the kernel. + * as such, we don't care about years<1970 etc, but assume everything + * is ok. Similarly, TZ etc is happily ignored. We just do everything + * as easily as possible. Let's find something public for the library + * routines (although I think minix times is public). + */ +/* + * PS. I hate whoever though up the year 1970 - couldn't they have gotten + * a leap-year instead? I also hate Gregorius, pope or no. I'm grumpy. + */ +#define MINUTE 60 +#define HOUR (60*MINUTE) +#define DAY (24*HOUR) +#define YEAR (365*DAY) + +/* interestingly, we assume leap-years */ +static int month[12] = { + 0, + DAY*(31), + DAY*(31+29), + DAY*(31+29+31), + DAY*(31+29+31+30), + DAY*(31+29+31+30+31), + DAY*(31+29+31+30+31+30), + DAY*(31+29+31+30+31+30+31), + DAY*(31+29+31+30+31+30+31+31), + DAY*(31+29+31+30+31+30+31+31+30), + DAY*(31+29+31+30+31+30+31+31+30+31), + DAY*(31+29+31+30+31+30+31+31+30+31+30) +}; + +long kernel_mktime(struct tm * tm) +{ + long res; + int year; + + year = tm->tm_year - 70; +/* magic offsets (y+1) needed to get leapyears right.*/ + res = YEAR*year + DAY*((year+1)/4); + res += month[tm->tm_mon]; +/* and (y+2) here. If it wasn't a leap-year, we have to adjust */ + if (tm->tm_mon>1 && ((year+2)%4)) + res -= DAY; + res += DAY*(tm->tm_mday-1); + res += HOUR*tm->tm_hour; + res += MINUTE*tm->tm_min; + res += tm->tm_sec; + return res; +} |