Date And +Time Handling Overview

Architectural relationships

The system maintains +two clocks:

a secure clock that +can only be set by kernel code or by an application that has TCB capability. +This is a clock that can be used by secure DRM applications.
a non-secure clock that +can be set by applications that require no specific capability. This is the +clock that is used for user-visible time displays.

The non-secure clock is implemented in terms of an offset from the +secure clock.

Both the secure time and the non-secure time can be +set using the System Static Functions API, and specifically:

Secure time

User::SetHomeTimeSecure(0
User::SetUTCTimeSecure()

Non-secure time

User::SetHomeTime()
User::SetUTCTime()

System locale settings, which affect date and time formatting, are +set through TLocale in the Locale Settings API.

Description

The API has three key concepts: point +in time, time utilities, and time interval.

Point +in time

The point in time is a 64-bit integer that represents +time as the number of microseconds since midnight on 1st January 0 AD, using +a nominal Gregorian calendar. It can be set to the current system time, can +have arithmetic and comparison operations performed on it, and can be converted +into a string formatted according to the locale and other options.

The +main point in time interface is provided by TTime. A support +class TDateTime is provided that allows time values to +be get and set in an easy-to-use format, such as year, month, day, rather +than as an integer.

The time value in a TTime object +can be set using either the secure time or the non-secure time.

Time utilities

The time utilities provides miscellaneous time +functions, for such things as checking for leap years.

The time utilities +interface is provided by Time.

Time interval

The time interval represents a period between +two points in time. Time intervals can be added or subtracted, either to or +from each other or to or from points in time.

The time interval interface +is provided by a base class TTimeIntervalBase and by a +family of derived classes for second, minute, hour, etc. intervals. A class +outside this hierarchy, TTimeIntervalMicroSeconds, is provided +for efficiency reasons (it alone stores its value as a 64-bit number).