reactos/ntoskrnl/rtl/time.c

   1 /* $Id: time.c,v 1.16 2002/12/08 16:23:32 robd Exp $
   2  *
   3  * COPYRIGHT:       See COPYING in the top level directory
   4  * PROJECT:         ReactOS kernel
   5  * FILE:            kernel/rtl/time.c
   6  * PURPOSE:         Conversion between Time and TimeFields
   7  * PROGRAMMER:      Rex Jolliff (rex@lvcablemodem.com)
   8  * UPDATE HISTORY:
   9  *                  Created 22/05/98
  10  *   08/03/98  RJJ  Implemented these functions
  11  */
  12
  13 /* INCLUDES *****************************************************************/
  14
  15 #include <ddk/ntddk.h>
  16
  17 #define NDEBUG
  18 #include <internal/debug.h>
  19
  20 #define TICKSPERMIN        600000000
  21 #define TICKSPERSEC        10000000
  22 #define TICKSPERMSEC       10000
  23 #define SECSPERDAY         86400
  24 #define SECSPERHOUR        3600
  25 #define SECSPERMIN         60
  26 #define MINSPERHOUR        60
  27 #define HOURSPERDAY        24
  28 #define EPOCHWEEKDAY       1
  29 #define DAYSPERWEEK        7
  30 #define EPOCHYEAR          1601
  31 #define DAYSPERNORMALYEAR  365
  32 #define DAYSPERLEAPYEAR    366
  33 #define MONSPERYEAR        12
  34
  35 #define TICKSTO1970         0x019db1ded53e8000LL
  36 #define TICKSTO1980         0x01a8e79fe1d58000LL
  37
  38
  39 static const int YearLengths[2] = {DAYSPERNORMALYEAR, DAYSPERLEAPYEAR};
  40 static const int MonthLengths[2][MONSPERYEAR] =
  41 {
  42         { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
  43         { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
  44 };
  45
  46 static __inline int IsLeapYear(int Year)
  47 {
  48   return Year % 4 == 0 && (Year % 100 != 0 || Year % 400 == 0) ? 1 : 0;
  49 }
  50
  51 static __inline void NormalizeTimeFields(CSHORT *FieldToNormalize,
  52                                          CSHORT *CarryField,
  53                                          int Modulus)
  54 {
  55   *FieldToNormalize = (CSHORT) (*FieldToNormalize - Modulus);
  56   *CarryField = (CSHORT) (*CarryField + 1);
  57 }
  58
  59 /* FUNCTIONS *****************************************************************/
  60
  61 VOID
  62 STDCALL
  63 RtlTimeToTimeFields(
  64         PLARGE_INTEGER liTime,
  65         PTIME_FIELDS TimeFields)
  66 {
  67   const int *Months;
  68   int LeapSecondCorrections, SecondsInDay, CurYear;
  69   int LeapYear, CurMonth, GMTOffset;
  70   long int Days;
  71   long long int Time = (long long int)liTime->QuadPart;
  72
  73     /* Extract millisecond from time and convert time into seconds */
  74   TimeFields->Milliseconds = (CSHORT) ((Time % TICKSPERSEC) / TICKSPERMSEC);
  75   Time = Time / TICKSPERSEC;
  76
  77     /* FIXME: Compute the number of leap second corrections here */
  78   LeapSecondCorrections = 0;
  79
  80     /* FIXME: get the GMT offset here */
  81   GMTOffset = 0;
  82
  83     /* Split the time into days and seconds within the day */
  84   Days = Time / SECSPERDAY;
  85   SecondsInDay = Time % SECSPERDAY;
  86
  87     /* Adjust the values for GMT and leap seconds */
  88   SecondsInDay += (GMTOffset - LeapSecondCorrections);
  89   while (SecondsInDay < 0)
  90     {
  91       SecondsInDay += SECSPERDAY;
  92       Days--;
  93     }
  94   while (SecondsInDay >= SECSPERDAY)
  95     {
  96       SecondsInDay -= SECSPERDAY;
  97       Days++;
  98     }
  99
 100     /* compute time of day */
 101   TimeFields->Hour = (CSHORT) (SecondsInDay / SECSPERHOUR);
 102   SecondsInDay = SecondsInDay % SECSPERHOUR;
 103   TimeFields->Minute = (CSHORT) (SecondsInDay / SECSPERMIN);
 104   TimeFields->Second = (CSHORT) (SecondsInDay % SECSPERMIN);
 105
 106     /* FIXME: handle the possibility that we are on a leap second (i.e. Second = 60) */
 107
 108     /* compute day of week */
 109   TimeFields->Weekday = (CSHORT) ((EPOCHWEEKDAY + Days) % DAYSPERWEEK);
 110
 111     /* compute year */
 112   CurYear = EPOCHYEAR;
 113   CurYear += Days / DAYSPERLEAPYEAR;
 114   Days -= (CurYear - EPOCHYEAR) * DAYSPERLEAPYEAR;
 115   CurYear--; /* The next calculation needs CurYear - 1 */
 116   Days += CurYear - CurYear / 4 + CurYear / 100 - CurYear / 400;
 117   CurYear++;
 118   Days -= EPOCHYEAR - 1 - (EPOCHYEAR -1) / 4 + (EPOCHYEAR -1) / 100 - (EPOCHYEAR - 1) / 400;
 119     /* FIXME: handle calendar modifications */
 120   while (1)
 121     {
 122       LeapYear = IsLeapYear(CurYear);
 123       if (Days < (long) YearLengths[LeapYear])
 124         {
 125           break;
 126         }
 127       CurYear++;
 128       Days = Days - (long) YearLengths[LeapYear];
 129     }
 130   TimeFields->Year = (CSHORT) CurYear;
 131
 132     /* Compute month of year */
 133   LeapYear = IsLeapYear(CurYear);
 134   Months = MonthLengths[LeapYear];
 135   for (CurMonth = 0; Days >= (long) Months[CurMonth]; CurMonth++)
 136     Days = Days - (long) Months[CurMonth];
 137   TimeFields->Month = (CSHORT) (CurMonth + 1);
 138   TimeFields->Day = (CSHORT) (Days + 1);
 139 }
 140
 141 BOOLEAN
 142 STDCALL
 143 RtlTimeFieldsToTime(
 144         PTIME_FIELDS tfTimeFields,
 145         PLARGE_INTEGER Time)
 146 {
 147   int CurMonth;
 148   long long int rcTime;
 149   TIME_FIELDS TimeFields = *tfTimeFields;
 150   const int *Months;
 151
 152   rcTime = 0;
 153
 154   /* Normalize the month value, because we don't know the length for month -1, 0, 13, 14, ... */
 155   if (TimeFields.Month < 1 || TimeFields.Month > 12)
 156   {
 157      TimeFields.Year += (TimeFields.Month - 1) / MONSPERYEAR;
 158      TimeFields.Month = ((TimeFields.Month - 1) % MONSPERYEAR) + 1;
 159      if (TimeFields.Month < 1)
 160      {
 161         TimeFields.Year--;
 162         TimeFields.Month += MONSPERYEAR;
 163      }
 164   }
 165     /* FIXME: handle calendar corrections here */
 166
 167   rcTime += (TimeFields.Year - EPOCHYEAR) * DAYSPERNORMALYEAR;
 168   /* Adjust leap years */
 169   rcTime += (TimeFields.Year - 1)/ 4 - (TimeFields.Year - 1) / 100 + (TimeFields.Year - 1) / 400;
 170   rcTime -= EPOCHYEAR / 4 - EPOCHYEAR / 100 + EPOCHYEAR / 400;
 171
 172     /* FIXME: handle calendar corrections here */
 173   Months = MonthLengths[IsLeapYear(TimeFields.Year)];
 174   for (CurMonth = 1; CurMonth < TimeFields.Month; CurMonth++)
 175     {
 176       rcTime += Months[CurMonth - 1];
 177     }
 178   rcTime += TimeFields.Day - 1;
 179   rcTime *= SECSPERDAY;
 180   rcTime += TimeFields.Hour * SECSPERHOUR + TimeFields.Minute * SECSPERMIN +
 181             TimeFields.Second;
 182   rcTime *= TICKSPERSEC;
 183   rcTime += TimeFields.Milliseconds * TICKSPERMSEC;
 184
 185     /* FIXME: handle UTC bias here */
 186 //  rcTime += UTCBias * TICKSPERMIN;
 187
 188   *Time = *(LARGE_INTEGER *)&rcTime;
 189
 190   return TRUE;
 191 }
 192
 193
 194 VOID
 195 STDCALL
 196 RtlSecondsSince1970ToTime(
 197         ULONG SecondsSince1970,
 198         PLARGE_INTEGER Time)
 199 {
 200    LONGLONG llTime;
 201
 202    llTime = (SecondsSince1970 * TICKSPERSEC) + TICKSTO1970;
 203
 204    *Time = *(LARGE_INTEGER *)&llTime;
 205 }
 206
 207
 208 VOID
 209 STDCALL
 210 RtlSecondsSince1980ToTime(
 211         ULONG SecondsSince1980,
 212         PLARGE_INTEGER Time)
 213 {
 214    LONGLONG llTime;
 215
 216    llTime = (SecondsSince1980 * TICKSPERSEC) + TICKSTO1980;
 217
 218    *Time = *(LARGE_INTEGER *)&llTime;
 219 }
 220
 221
 222 BOOLEAN
 223 STDCALL
 224 RtlTimeToSecondsSince1970(
 225         PLARGE_INTEGER Time,
 226         PULONG SecondsSince1970)
 227 {
 228    LARGE_INTEGER liTime;
 229
 230    liTime.QuadPart = Time->QuadPart - TICKSTO1970;
 231    liTime.QuadPart = liTime.QuadPart / TICKSPERSEC;
 232
 233    if (liTime.u.HighPart != 0)
 234       return FALSE;
 235
 236    *SecondsSince1970 = liTime.u.LowPart;
 237
 238    return TRUE;
 239 }
 240
 241
 242 BOOLEAN
 243 STDCALL
 244 RtlTimeToSecondsSince1980(
 245         PLARGE_INTEGER Time,
 246         PULONG SecondsSince1980)
 247 {
 248    LARGE_INTEGER liTime;
 249
 250    liTime.QuadPart = Time->QuadPart - TICKSTO1980;
 251    liTime.QuadPart = liTime.QuadPart / TICKSPERSEC;
 252
 253    if (liTime.u.HighPart != 0)
 254       return FALSE;
 255
 256    *SecondsSince1980 = liTime.u.LowPart;
 257
 258    return TRUE;
 259 }
 260
 261 /* EOF */