hades.models.flipflops
Class JkffMetastable

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

All Implemented Interfaces:

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

public class JkffMetastable

extends GenericFlipflop

implements Simulatable, java.io.Serializable

Jkff: a falling-edge triggered JK-flipflop with asynchronous clear. Unlike Jkff, which models a typical CMOS-style library flipflop with strict input-value checking, this flipflop model won't generate 'U' or 'X' output values, but generates random output values instead. The main use of this flipflop model is for the simulation of "legacy circuits" like the TTL 74xx series counters, which often don't use or hardwire the flipflop reset inputs.

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

JkffMetastable()

Method Summary

void	evaluate(java.lang.Object arg) evaluate: check the J, K, NC inputs and calculate Q and NQ.
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, elaborate, 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

elaborate, message

Constructor Detail

JkffMetastable

public JkffMetastable()

Method Detail

evaluate

public void evaluate(java.lang.Object arg)

evaluate: check the J, K, NC inputs and calculate Q and NQ. See any logic design textbook for the function table of a JK flipflop. If any input is undefined or a timing-violation is detected, the flipflop state and Q/NQ outputs are set to 'X'.

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.