org.opencores.placement
Class Annealing

java.lang.Object
  |
  +--org.opencores.placement.Annealing

public class Annealing

extends java.lang.Object

This is main class, consisting of simulated annealing routine. Nodes must be are already placed correctly (using preplacement) and their pos (.x, .y) and index .idx are set. All work here is done using indexes, but coordinates are also maintaned to speed up placement.

Alpha functions and some other dinamic parameters are adopted from VPR.

See Also:

Field Summary

private double[][]	alpha Discrete temperature update - alpha function.
private float[]	costs
private int[][]	distance Precalculated distance based on (x,y) coordinates.
private static double	DONE_CONSTANT Stoping treshold.
private Graph	g graph we are working on
private static int	INITIAL_TEMP_K Initial temperature coefficient.
private int	INNER_NUM Number of inner loop execution times.
private static int	INNER_NUM_K Coefficient, which linearly changes number of inner loop executions.
private NodeGPC[]	posGPC table of all possible GPC positions (and current assignments)
private NodeIOC[]	posIOC table of all possible Port positions (and current assignments)
private double	temp current temperature, @see setTemp
private int	tempAccepted number of (accepted) moves performed per current temperature
private int	tempMoves number of (possible) moves performed per current temperature
private int	tempWiringChange total wiring change per current temperature
private int	wiringCost current total wiring cost, @see calcTotalWiringCost, getWiringCost

Constructor Summary

Annealing(Graph g)
Construct and resets new SA object on graph g.

Method Summary

private boolean	allowMove(float dCost) Decides whether move with delta cost dCost should be taken.
void	anneal() simulates anneal at current temperature temp.
private void	buildDist() Build estimated #hops for each vector (dx, dy).
private int	calcTotalWiringCost() Wiring length is sum of sizes of all minimum spanning trees.
private float	checkWiringCost() Checks MST trees currently built with stored number in nets.cost
private int	dist(int dx, int dy) Returns estimated distance of vector (dx, dy).
boolean	doneCriteria() Decides whether annealing has good solution and it is unlikely that we will find it, so we should stop.
double	getTemp() Returns current temperature.
int	getWiringCost() Returns current total wiring cost.
private static int	manhattan(int dx, int dy) Returns manhattan distance of vector (dx, dy).
private boolean	move(IndexedNode a, IndexedNode b, int bx, int by, int bidx) Returns true if node has been moved from a to b
private void	move(NodeGPC a) Tries to move node n, using current Conf.
private void	move(NodeIOC a) Tries to move node n, using current configuration
private float	moveCost(Node n, int x, int y) Estimates cost (wiring cost change) of move, after n is moved to (x,y).
private int	MST(Net nt) Calculates minimum spanning tree size.
void	reset() Resets SA.
void	setTemp(double temp) Changes temperature and resets temperature specific data.
private double	stdDev() Calculates standard deviation of one random move for each graph node.
private boolean	stopCriteria() Decides whether we should stop annealing at current temperature.
private void	takeBackMove(Node n) This function is called when move is not accepted, and updates net MST costs, to previous moveCost costs
void	updateTemperature() Changes temperature - function alpha(T)

Methods inherited from class java.lang.Object

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

Field Detail

INNER_NUM_K

private static final int INNER_NUM_K

Coefficient, which linearly changes number of inner loop executions.

INITIAL_TEMP_K

private static final int INITIAL_TEMP_K

Initial temperature coefficient. Larger, more moves will be accepted at start.

INNER_NUM

private int INNER_NUM

Number of inner loop execution times. Set at reset().

DONE_CONSTANT

private static final double DONE_CONSTANT

Stoping treshold. Larger it is sooner we will stop. Should be positive.

g

private Graph g

graph we are working on

posGPC

private NodeGPC[] posGPC

table of all possible GPC positions (and current assignments)

posIOC

private NodeIOC[] posIOC

table of all possible Port positions (and current assignments)

temp

private double temp

current temperature, @see setTemp

wiringCost

private int wiringCost

current total wiring cost, @see calcTotalWiringCost, getWiringCost

tempMoves

private int tempMoves

number of (possible) moves performed per current temperature

tempAccepted

private int tempAccepted

number of (accepted) moves performed per current temperature

tempWiringChange

private int tempWiringChange

total wiring change per current temperature

alpha

private final double[][] alpha

Discrete temperature update - alpha function.

First number is acceptance ratio, second coefficient K, and T = K * T

costs

private float[] costs

distance

private int[][] distance

Precalculated distance based on (x,y) coordinates.

Constructor Detail

Annealing

public Annealing(Graph g)

Construct and resets new SA object on graph g.

Parameters:

g - mapped, preplaced graph to work on

Method Detail

reset

public void reset()

Resets SA. Should be called every time, when SA is restarted.

setTemp

public void setTemp(double temp)

Changes temperature and resets temperature specific data.

Should be called after each temp change.

Parameters:

temp - new temperature

updateTemperature

public void updateTemperature()

Changes temperature - function alpha(T)

anneal

public void anneal()

simulates anneal at current temperature temp.

stopCriteria

private final boolean stopCriteria()

Decides whether we should stop annealing at current temperature. Also called InnerLoop criterion.

Returns:

true when annealing at current temperature should be stopped, false otherwise

doneCriteria

public final boolean doneCriteria()

Decides whether annealing has good solution and it is unlikely that we will find it, so we should stop.

NOTE: call this before updateTemperature, since it destroys temperature dependent data, needed here

Returns:

true when annealing should be stopped, false otherwise

move

private void move(NodeGPC a)

Tries to move node n, using current Conf.

Parameters:

temp - current temperature

a - GPC node to move

move

private void move(NodeIOC a)

Tries to move node n, using current configuration

Parameters:

an - IOC node to move

Returns:

wiring cost change

allowMove

private final boolean allowMove(float dCost)

Decides whether move with delta cost dCost should be taken.

Parameters:

dCost - movement delta cost

Returns:

true if decision should be taken, false otherwise.

moveCost

private final float moveCost(Node n,
                             int x,
                             int y)

Estimates cost (wiring cost change) of move, after n is moved to (x,y).

NOTE: no replacement is made. Does not calculate replacement cost of node at (x,y).

This function stores computed costs in costs, which can be used later if move is not accepted.

Proceed as following:

1. find closest pin on each a's port net, and calculate cost to move it to next neighbour or if no other to new position

2. find closest pin for each a's port net, based on new position

Parameters:

n - node to calculate movement cost on

dest - node, we will exchange n with

x - destination x position

y - destination y position

Returns:

movement cost

takeBackMove

private void takeBackMove(Node n)

This function is called when move is not accepted, and updates net MST costs, to previous moveCost costs

See Also:

moveCost

move

private boolean move(IndexedNode a,
                     IndexedNode b,
                     int bx,
                     int by,
                     int bidx)

Returns true if node has been moved from a to b

buildDist

private final void buildDist()

Build estimated #hops for each vector (dx, dy). Calculated table is stored in distance

dist

private final int dist(int dx,
                       int dy)

Returns estimated distance of vector (dx, dy).

Parameters:

dx - vector x component

dy - vector y component

Returns:

min distance

manhattan

private static final int manhattan(int dx,
                                   int dy)

Returns manhattan distance of vector (dx, dy).

Parameters:

dx - vector x component

dy - vector y component

Returns:

distance

MST

private int MST(Net nt)

Calculates minimum spanning tree size.

Parameters:

net - to compute MST on

Returns:

MST size

calcTotalWiringCost

private int calcTotalWiringCost()

Wiring length is sum of sizes of all minimum spanning trees.

Returns:

total wiring cost

checkWiringCost

private float checkWiringCost()

Checks MST trees currently built with stored number in nets.cost

Returns:

difference

stdDev

private double stdDev()

Calculates standard deviation of one random move for each graph node.

Returns:

standard deviation of cost

getWiringCost

public int getWiringCost()

Returns current total wiring cost.

Returns:

total wiring cost

getTemp

public double getTemp()

Returns current temperature.

Returns:

current temperature

See Also:

temp