72 lines
2.0 KiB
C
72 lines
2.0 KiB
C
#include <stddef.h>
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#include <stdint.h>
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#include <lib/time.h>
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#if bios == 1
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# include <lib/real.h>
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#elif uefi == 1
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# include <efi.h>
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#endif
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#include <lib/blib.h>
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// Julian date calculation from https://en.wikipedia.org/wiki/Julian_day
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static uint64_t get_jdn(uint8_t days, uint8_t months, uint16_t years) {
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return (1461 * (years + 4800 + (months - 14)/12))/4 + (367 *
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(months - 2 - 12 * ((months - 14)/12)))/12 -
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(3 * ((years + 4900 + (months - 14)/12)/100))/4
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+ days - 32075;
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}
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static uint64_t get_unix_epoch(uint8_t seconds, uint8_t minutes, uint8_t hours,
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uint8_t days, uint8_t months, uint16_t years) {
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uint64_t jdn_current = get_jdn(days, months, years);
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uint64_t jdn_1970 = get_jdn(1, 1, 1970);
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uint64_t jdn_diff = jdn_current - jdn_1970;
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return (jdn_diff * (60 * 60 * 24)) + hours * 3600 + minutes * 60 + seconds;
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}
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#if bios == 1
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uint64_t time(void) {
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struct rm_regs r;
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again:
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r = (struct rm_regs){0};
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r.eax = 0x0400;
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rm_int(0x1a, &r, &r);
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uint8_t day = bcd_to_int( r.edx & 0x00ff);
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uint8_t month = bcd_to_int((r.edx & 0xff00) >> 8);
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uint16_t year = bcd_to_int( r.ecx & 0x00ff) +
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/* century */ bcd_to_int((r.ecx & 0xff00) >> 8) * 100;
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r = (struct rm_regs){0};
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r.eax = 0x0200;
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rm_int(0x1a, &r, &r);
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uint8_t second = bcd_to_int((r.edx & 0xff00) >> 8);
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uint8_t minute = bcd_to_int( r.ecx & 0x00ff);
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uint8_t hour = bcd_to_int((r.ecx & 0xff00) >> 8);
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// Check RTC day wraparound
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r = (struct rm_regs){0};
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r.eax = 0x0400;
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rm_int(0x1a, &r, &r);
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if (bcd_to_int(r.edx & 0x00ff) != day) {
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goto again;
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}
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return get_unix_epoch(second, minute, hour, day, month, year);
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}
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#endif
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#if uefi == 1
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uint64_t time(void) {
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EFI_TIME time;
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gRT->GetTime(&time, NULL);
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return get_unix_epoch(time.Second, time.Minute, time.Hour,
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time.Day, time.Month, time.Year);
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}
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#endif
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