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#include <AK/Assertions.h>
#include <Kernel/CMOS.h>
#include <Kernel/RTC.h>
namespace RTC {
static time_t s_boot_time;
void initialize()
{
s_boot_time = now();
}
time_t boot_time()
{
return s_boot_time;
}
static bool update_in_progress()
{
return CMOS::read(0x0a) & 0x80;
}
inline bool is_leap_year(unsigned year)
{
return ((year % 4 == 0) && ((year % 100 != 0) || (year % 400) == 0));
}
static unsigned days_in_months_since_start_of_year(unsigned month, unsigned year)
{
ASSERT(month <= 11);
unsigned days = 0;
switch (month) {
case 11:
days += 30;
[[fallthrough]];
case 10:
days += 31;
[[fallthrough]];
case 9:
days += 30;
[[fallthrough]];
case 8:
days += 31;
[[fallthrough]];
case 7:
days += 31;
[[fallthrough]];
case 6:
days += 30;
[[fallthrough]];
case 5:
days += 31;
[[fallthrough]];
case 4:
days += 30;
[[fallthrough]];
case 3:
days += 31;
[[fallthrough]];
case 2:
if (is_leap_year(year))
days += 29;
else
days += 28;
[[fallthrough]];
case 1:
days += 31;
}
return days;
}
static unsigned days_in_years_since_epoch(unsigned year)
{
unsigned days = 0;
while (year > 1969) {
days += 365;
if (is_leap_year(year))
++days;
--year;
}
return days;
}
u8 bcd_to_binary(u8 bcd)
{
return (bcd & 0x0F) + ((bcd >> 4) * 10);
}
void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
{
while (update_in_progress())
;
u8 status_b = CMOS::read(0x0b);
second = CMOS::read(0x00);
minute = CMOS::read(0x02);
hour = CMOS::read(0x04);
day = CMOS::read(0x07);
month = CMOS::read(0x08);
year = CMOS::read(0x09);
if (!(status_b & 0x04)) {
second = bcd_to_binary(second);
minute = bcd_to_binary(minute);
hour = bcd_to_binary(hour & 0x70);
day = bcd_to_binary(day);
month = bcd_to_binary(month);
year = bcd_to_binary(year);
}
if (!(status_b & 0x02) && (hour & 0x80)) {
hour = ((hour & 0x7F) + 12) % 24;
}
year += 2000;
}
time_t now()
{
// FIXME: We should probably do something more robust here.
// Perhaps read all the values twice and verify that they were identical.
// We don't want to be caught in the middle of an RTC register update.
while (update_in_progress())
;
unsigned year, month, day, hour, minute, second;
read_registers(year, month, day, hour, minute, second);
kprintf("year: %d, month: %d, day: %d\n", year, month, day);
ASSERT(year >= 2018);
return days_in_years_since_epoch(year - 1) * 86400
+ days_in_months_since_start_of_year(month - 1, year) * 86400
+ (day - 1) * 86400
+ hour * 3600
+ minute * 60
+ second;
}
}
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