Implement time conversion routines for Unix and XT epoch formats

xtoskrnl/rtl/time.cc

@@ -0,0 +1,129 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/rtl/time.cc
+ * DESCRIPTION:     Time conversion support
+ * DEVELOPERS:      Aiken Harris <harraiken91@gmail.com>
+ */
+
+#include <xtos.hh>
+
+
+/**
+ * Determines if a given year is a leap year in the Gregorian calendar.
+ *
+ * @param Year
+ *        Supplies the year to be checked.
+ *
+ * @return This routine returns TRUE if the year is a leap year, FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+BOOLEAN
+RTL::Time::LeapYear(SHORT Year)
+{
+    return ((Year % 4 == 0 && Year % 100 != 0) || (Year % 400 == 0)) ? TRUE : FALSE;
+}
+
+/**
+ * Converts a TIME_FIELDS calendar structure to a 64-bit Unix timestamp.
+ *
+ * @param TimeFields
+ *        Supplies a pointer to a fully populated TIME_FIELDS structure.
+ *
+ * @param UnixTime
+ *        Supplies a pointer to a 64-bit integer that receives the number of
+ *        seconds elapsed since January 1, 1970.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+XTSTATUS
+RTL::Time::TimeFieldsToUnixEpoch(IN PTIME_FIELDS TimeFields,
+                                 OUT PLONGLONG UnixTime)
+{
+    LONGLONG TotalSeconds;
+    LARGE_INTEGER XtTime;
+    XTSTATUS Status;
+
+    /* Convert to XT Epoch */
+    Status = TimeFieldsToXtEpoch(TimeFields, &XtTime);
+    if(Status != STATUS_SUCCESS)
+    {
+        /* Failed to convert to XT Epoch, return error code */
+        return Status;
+    }
+
+    /* Convert 100-nanosecond intervals (TICKS) to whole seconds */
+    TotalSeconds = XtTime.QuadPart / TICKS_PER_SECOND;
+
+    /* Subtract the number of seconds between January 1, 1601 and January 1, 1970 */
+    *UnixTime = TotalSeconds - 11644473600LL;
+
+    /* Return success */
+    return STATUS_SUCCESS;
+}
+
+/**
+ * Converts a TIME_FIELDS calendar structure to a 64-bit XT timestamp.
+ *
+ * @param TimeFields
+ *        Supplies a pointer to a fully populated TIME_FIELDS structure.
+ *
+ * @param Time
+ *        Supplies a pointer to variable that receives the converted time value in 100-nanosecond
+ *        intervals since January 1, 1601.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+XTSTATUS
+RTL::Time::TimeFieldsToXtEpoch(IN PTIME_FIELDS TimeFields,
+                               OUT PLARGE_INTEGER XtTime)
+{
+    ULONG Leap, ElapsedYears, ElapsedDays;
+    ULONGLONG TotalSeconds;
+
+    /* Check leap year */
+    Leap = LeapYear(TimeFields->Year) ? 1 : 0;
+
+    /* Validate input data */
+    if(TimeFields->Hour < 0 || TimeFields->Hour > 23 ||
+       TimeFields->Minute < 0 || TimeFields->Minute > 59 ||
+       TimeFields->Second < 0 || TimeFields->Second > 59 ||
+       TimeFields->Milliseconds < 0 || TimeFields->Milliseconds > 999 ||
+       TimeFields->Year < 1601 || TimeFields->Year > 30827 ||
+       TimeFields->Month < 1 || TimeFields->Month > 12 ||
+       TimeFields->Day < 1 || TimeFields->Day > DaysInMonth[Leap][TimeFields->Month - 1])
+    {
+        /* Invalid input data, return error code */
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    /* Calculate days elapsed in previous years */
+    ElapsedYears = (ULONG)(TimeFields->Year - 1601);
+    ElapsedDays = (ElapsedYears * 365) + (ElapsedYears / 4) - (ElapsedYears / 100) + (ElapsedYears / 400);
+
+    /* Add days elapsed in previous months of the current year */
+    ElapsedDays += DaysPrecedingMonth[Leap][TimeFields->Month - 1];
+
+    /* Add days elapsed in the current month */
+    ElapsedDays += (TimeFields->Day - 1);
+
+    /* Calculate a total number of seconds */
+    TotalSeconds = ((ULONGLONG)ElapsedDays * SECONDS_PER_DAY) +
+                   ((ULONGLONG)TimeFields->Hour * SECONDS_PER_HOUR) +
+                   ((ULONGLONG)TimeFields->Minute * SECONDS_PER_MINUTE) +
+                   (ULONGLONG)TimeFields->Second;
+
+    /* Convert to 100-ns intervals and slap milliseconds on top */
+    Time->QuadPart = (TotalSeconds * TICKS_PER_SECOND) + ((ULONGLONG)TimeFields->Milliseconds * TICKS_PER_MILLISECOND);
+
+    /* Return success */
+    return STATUS_SUCCESS;
+}