boot/armllb/hw/time.c

   1 /*
   2  * PROJECT:         ReactOS Boot Loader
   3  * LICENSE:         BSD - See COPYING.ARM in the top level directory
   4  * FILE:            boot/armllb/hw/time.c
   5  * PURPOSE:         LLB Time Routines
   6  * PROGRAMMERS:     ReactOS Portable Systems Group
   7  */
   8
   9 #include "precomp.h"
  10
  11 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
  12
  13 UCHAR LlbDaysInMonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  14 TIMEINFO LlbTime;
  15
  16 BOOLEAN
  17 NTAPI
  18 LlbIsLeapYear(IN ULONG Year)
  19 {
  20     /* Every 4, 100, or 400 years */
  21     return (!(Year % 4) && (Year % 100)) || !(Year % 400);
  22 }
  23
  24 ULONG
  25 NTAPI
  26 LlbDayOfMonth(IN ULONG Month,
  27               IN ULONG Year)
  28 {
  29     /* Check how many days a month has, accounting for leap yearS */
  30     return LlbDaysInMonth[Month] + (LlbIsLeapYear(Year) && Month == 1);
  31 }
  32
  33 VOID
  34 NTAPI
  35 LlbConvertRtcTime(IN ULONG RtcTime,
  36                   OUT TIMEINFO* TimeInfo)
  37 {
  38     ULONG Month, Year, Days, DaysLeft;
  39
  40     /* Count the days, keep the minutes */
  41     Days = RtcTime / 86400;
  42     RtcTime -= Days * 86400;
  43
  44     /* Get the year, based on days since 1970 */
  45     Year = 1970 + Days / 365;
  46
  47     /* Account for leap years which changed the number of days/year */
  48     Days -= (Year - 1970) * 365 + LEAPS_THRU_END_OF(Year - 1) - LEAPS_THRU_END_OF(1970 - 1);
  49     if (Days < 0)
  50     {
  51         /* We hit a leap year, so fixup the math */
  52         Year--;
  53         Days += 365 + LlbIsLeapYear(Year);
  54     }
  55
  56     /* Count months */
  57     for (Month = 0; Month < 11; Month++)
  58     {
  59         /* How many days in this month? */
  60         DaysLeft = Days - LlbDayOfMonth(Month, Year);
  61         if (DaysLeft < 0) break;
  62
  63         /* How many days left total? */
  64         Days = DaysLeft;
  65     }
  66
  67     /* Write the structure */
  68     TimeInfo->Year = Year;
  69     TimeInfo->Day = Days + 1;
  70     TimeInfo->Month = Month + 1;
  71     TimeInfo->Hour = RtcTime / 3600;
  72     RtcTime -= TimeInfo->Hour * 3600;
  73     TimeInfo->Minute = RtcTime / 60;
  74     TimeInfo->Second = RtcTime - TimeInfo->Minute * 60;
  75 }
  76
  77 TIMEINFO*
  78 NTAPI
  79 LlbGetTime(VOID)
  80 {
  81     ULONG RtcTime;
  82
  83     /* Read RTC time */
  84     RtcTime = LlbHwRtcRead();
  85
  86     /* Convert it */
  87     LlbConvertRtcTime(RtcTime, &LlbTime);
  88     return &LlbTime;
  89 }
  90
  91 /* EOF */