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103 lines
2.2 KiB
C++
103 lines
2.2 KiB
C++
#include "RTC.h"
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#include "CMOS.h"
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#include <AK/Assertions.h>
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namespace RTC {
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static time_t s_boot_time;
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void initialize()
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{
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byte cmos_mode = CMOS::read(0x0b);
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cmos_mode |= 2; // 24 hour mode
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cmos_mode |= 4; // No BCD mode
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CMOS::write(0x0b, cmos_mode);
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s_boot_time = now();
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}
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time_t boot_time()
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{
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return s_boot_time;
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}
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static bool update_in_progress()
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{
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return CMOS::read(0x0a) & 0x80;
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}
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inline bool is_leap_year(unsigned year)
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{
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return ((year % 4 == 0) && ((year % 100 != 0) || (year % 400) == 0));
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}
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static unsigned days_in_months_since_start_of_year(unsigned month, unsigned year)
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{
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switch (month) {
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case 11: return 30;
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case 10: return 31;
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case 9: return 30;
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case 8: return 31;
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case 7: return 31;
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case 6: return 30;
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case 5: return 31;
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case 4: return 30;
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case 3: return 31;
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case 2:
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if (is_leap_year(year))
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return 29;
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return 28;
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case 1: return 31;
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default: return 0;
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}
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}
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static unsigned days_in_years_since_epoch(unsigned year)
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{
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unsigned days = 0;
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while (year > 1969) {
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days += 365;
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if (is_leap_year(year))
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++days;
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--year;
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}
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return days;
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}
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void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
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{
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while (update_in_progress())
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;
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year = (CMOS::read(0x32) * 100) + CMOS::read(0x09);
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month = CMOS::read(0x08);
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day = CMOS::read(0x07);
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hour = CMOS::read(0x04);
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minute = CMOS::read(0x02);
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second = CMOS::read(0x00);
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}
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time_t now()
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{
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// FIXME: We should probably do something more robust here.
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// Perhaps read all the values twice and verify that they were identical.
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// We don't want to be caught in the middle of an RTC register update.
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while (update_in_progress())
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;
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unsigned year, month, day, hour, minute, second;
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read_registers(year, month, day, hour, minute, second);
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ASSERT(year >= 2018);
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return days_in_years_since_epoch(year - 1) * 86400
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+ days_in_months_since_start_of_year(month - 1, year) * 86400
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+ day * 86400
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+ hour * 3600
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+ minute * 60
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+ second;
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}
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}
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