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
  15 #ifndef _ZOOM2_
  16 TIMEINFO LlbTime;
  17 #else
  18 extern TIMEINFO LlbTime;
  19 #endif
  20
  21 BOOLEAN
  22 NTAPI
  23 LlbIsLeapYear(IN ULONG Year)
  24 {
  25     /* Every 4, 100, or 400 years */
  26     return (!(Year % 4) && (Year % 100)) || !(Year % 400);
  27 }
  28
  29 ULONG
  30 NTAPI
  31 LlbDayOfMonth(IN ULONG Month,
  32               IN ULONG Year)
  33 {
  34     /* Check how many days a month has, accounting for leap yearS */
  35     return LlbDaysInMonth[Month] + (LlbIsLeapYear(Year) && Month == 1);
  36 }
  37
  38 VOID
  39 NTAPI
  40 LlbConvertRtcTime(IN ULONG RtcTime,
  41                   OUT TIMEINFO* TimeInfo)
  42 {
  43     ULONG Month, Year, Days, DaysLeft;
  44
  45     /* Count the days, keep the minutes */
  46     Days = RtcTime / 86400;
  47     RtcTime -= Days * 86400;
  48
  49     /* Get the year, based on days since 1970 */
  50     Year = 1970 + Days / 365;
  51
  52     /* Account for leap years which changed the number of days/year */
  53     Days -= (Year - 1970) * 365 + LEAPS_THRU_END_OF(Year - 1) - LEAPS_THRU_END_OF(1970 - 1);
  54     if (Days < 0)
  55     {
  56         /* We hit a leap year, so fixup the math */
  57         Year--;
  58         Days += 365 + LlbIsLeapYear(Year);
  59     }
  60
  61     /* Count months */
  62     for (Month = 0; Month < 11; Month++)
  63     {
  64         /* How many days in this month? */
  65         DaysLeft = Days - LlbDayOfMonth(Month, Year);
  66         if (DaysLeft < 0) break;
  67
  68         /* How many days left total? */
  69         Days = DaysLeft;
  70     }
  71
  72     /* Write the structure */
  73     TimeInfo->Year = Year;
  74     TimeInfo->Day = Days + 1;
  75     TimeInfo->Month = Month + 1;
  76     TimeInfo->Hour = RtcTime / 3600;
  77     RtcTime -= TimeInfo->Hour * 3600;
  78     TimeInfo->Minute = RtcTime / 60;
  79     TimeInfo->Second = RtcTime - TimeInfo->Minute * 60;
  80 }
  81
  82 TIMEINFO*
  83 NTAPI
  84 LlbGetTime(VOID)
  85 {
  86     ULONG RtcTime;
  87
  88     /* Read RTC time */
  89     RtcTime = LlbHwRtcRead();
  90 #ifndef _ZOOM2_
  91     /* Convert it */
  92     LlbConvertRtcTime(RtcTime, &LlbTime);
  93 #endif
  94     return &LlbTime;
  95 }
  96
  97 /* EOF */