hades.models.flipflops
Class DffrMetastable

java.lang.Object
  hades.simulator.SimObject
      hades.models.flipflops.GenericFlipflop
          hades.models.flipflops.DffrMetastable

All Implemented Interfaces:

Assignable, java.lang.Cloneable, ContextToolTip, java.io.Serializable, Simulatable

public class DffrMetastable

extends GenericFlipflop

implements Simulatable, java.io.Serializable

DffrMetastable: a rising-edge triggered metastable D-flipflop.

Unlike Dff, this simulation component models a metastable flipflop which won't generate 'U' or 'X' values, but is set to random '0'/'1' StdLogic1164 values at initialization and on every hazard or undefined input condition.

Note that the delay for the propagation of this random value is random, too, with a delay of up to fifty times the usual flipflop propagation delay, t_pass.

Signals are expected to be StdLogic1164 objects.

See Also:

Serialized Form

Field Summary

Fields inherited from class hades.models.flipflops.GenericFlipflop

port_NQ, port_Q, t_hold, t_pass, t_setup

Fields inherited from class hades.simulator.SimObject

classloader, console, debug, editor, name, parent, ports, propertySheet, simulator, symbol, versionId, visible

Constructor Summary

DffrMetastable()

Method Summary

void	elaborate(java.lang.Object arg) elaborate: store a reference to the simulator, then call evaluate() to generate a random initial 0/1 output value.
void	evaluate(java.lang.Object arg) evaluate: calculate a new output value for this metastable DFF.
int	getRandom01Value() get a random StdLogic1164 0/1 value (with probability 0.5).
double	getRandomDelay() get a random delay time, which may be up to 50 times the value of the current gate propagation delay, t_pass.

Methods inherited from class hades.models.flipflops.GenericFlipflop

assign, configure, getDelay, getHoldTime, getSetupTime, getToolTip, initialize, scheduleEvent, scheduleEventAfter, scheduleOutputValue, scheduleOutputValueAfter, setDelay, setDelay, setHoldTime, setHoldTime, setSetupTime, setSetupTime, write

Methods inherited from class hades.simulator.SimObject

constructDynamicSymbol, copy, getBindkey, getClassLoader, getDebug, getEditor, getExternalResources, getFullName, getName, getParent, getPort, getPorts, getPropertySheet, getResourceAsStream, getSimulator, getSymbol, getSymbolResourceName, getVersionId, isVisible, keyPressed, message, mousePressed, needsDynamicSymbol, needsExternalResources, setClassLoader, setConsole, setDebug, setEditor, setName, setParent, setPorts, setSimulator, setSymbol, setVersionId, setVisible, tearDown, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface hades.simulator.Simulatable

message

Constructor Detail

DffrMetastable

public DffrMetastable()

Method Detail

elaborate

public void elaborate(java.lang.Object arg)

elaborate: store a reference to the simulator, then call evaluate() to generate a random initial 0/1 output value.

Specified by:

elaborate in interface Simulatable

Overrides:

elaborate in class GenericFlipflop

evaluate

public void evaluate(java.lang.Object arg)

evaluate: calculate a new output value for this metastable DFF. Check for a rising-edge on the C input and propagate the D input. If either C or D are undefined, or if setup- or hold-time violations are detected, this metastable DFF will enter a random 0/1 state after a random delay. A low value on NR resets the flipflop.

Specified by:

evaluate in interface Simulatable

Overrides:

evaluate in class SimObject

Parameters:

arg - an arbitrary object argument

getRandom01Value

public int getRandom01Value()

get a random StdLogic1164 0/1 value (with probability 0.5).

getRandomDelay

public double getRandomDelay()

get a random delay time, which may be up to 50 times the value of the current gate propagation delay, t_pass.