se.lth.cs.realtime
Class Timebase

java.lang.Object
  |
  +--se.lth.cs.realtime.Timebase

public class Timebase

extends java.lang.Object

The time-base class, mapping ticks to time. This class is needed for the following reasons:

• To obtain necessary resolution of the time variable, both for ordinary PCs/workstations and fast embedded controllers, even if the time is stored in a variable of a built in data type (long in this case).
• To permit applications to run in a local timescale using a real-time clocks that is not calibrated w.r.t. real-world time. This is the case in many small control applications.
• To permit subsystems (e.g. for planning or simulation) to run in a local time-scale. This will permit hierachical time-bases (via the envTimebase) but that is not yet supported.

Ordinary applications/users: Use default constructor .... this class currently only supports the default System time-base.

See Also:

javax.media.TimeBase, RTEvent

Field Summary

protected Timebase	envTimebase The time base of the surrounding system, such as the real world.
protected int	milliRate Ticks per milli-second.
protected int	nanoRate Ticks per nano-seconds.
protected int	rate Ticks per second.
protected double	scale Seconds per tick.
protected long	start The start of time, in milliseconds relative to beginning of 1970.

Constructor Summary

Timebase()
Constructor for default system time, using ticks for milli-seconds from beginning of 1970 as for System.currentTimeMillis().

Timebase(long origin, long pace)
Constructor for a time base starting with time zero at origin and with pace system dependent ticks per milliseconds.

Method Summary

long	millis(long timestamp) Express the timestamp (number of ticks) in milli-seconds.
long	nanos(long timestamp) Express the timestamp in nano-seconds.
long	pace() Rate of clock ticks per second.
double	physicalSeconds(long timestamp) Obtain physical real-world time.
double	seconds(long timestamp) Express the timestamp (that is, number of clock ticks) in seconds.
long	time0() The start of this time base, possibly relative to an enclosing time base, and expressed in seconds from beginning 1970.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

start

protected final long start

The start of time, in milliseconds relative to beginning of 1970.

scale

protected final double scale

Seconds per tick.

rate

protected final int rate

Ticks per second.

milliRate

protected final int milliRate

Ticks per milli-second.

nanoRate

protected final int nanoRate

Ticks per nano-seconds.

envTimebase

protected Timebase envTimebase

The time base of the surrounding system, such as the real world. If null, the system time is used. That is, System.currentTimeMillis() is valid in the scale of time since this is an ordinary RT application.

Constructor Detail

Timebase

public Timebase()

Constructor for default system time, using ticks for milli-seconds from beginning of 1970 as for System.currentTimeMillis().

Timebase

public Timebase(long origin,
                long pace)

Constructor for a time base starting with time zero at origin and with pace system dependent ticks per milliseconds. To represent the time in an embedded controller without battery supported clock (time realative to start of system) use REL_TIME as the origin argument.

Method Detail

physicalSeconds

public double physicalSeconds(long timestamp)
                       throws java.lang.IllegalStateException

Obtain physical real-world time. In ordinary applications the returned value will be equal to the value returned by seconds; that method should be used except in special cases of simulation, any-time algorithms, self-contioness robots, etc.

See Also:

seconds(long)

seconds

public double seconds(long timestamp)

Express the timestamp (that is, number of clock ticks) in seconds.

millis

public long millis(long timestamp)

Express the timestamp (number of ticks) in milli-seconds.

nanos

public long nanos(long timestamp)

Express the timestamp in nano-seconds. Under construction...

time0

public long time0()

The start of this time base, possibly relative to an enclosing time base, and expressed in seconds from beginning 1970.

pace

public long pace()

Rate of clock ticks per second.