signalproc.algorithms

Class Counter

java.lang.Object

signalproc.algorithms.Counter

public class Counter
extends java.lang.Object

Class Counter provides counters that can simulate some operations using nested loops. This is useful when a program does not know to what depth loops must be nested, eg if this depends on a parameter. Such loops cannot be programmed, but can be achieved by recursion. Counter provides an alternative. Each Counter counts iterations of one loop; the Counters are linked in a list, and when one Counter finishes its loop cycle it is re-initialized and the next-previous Counter in the list is advanced by one.

As presently constructed, Counters do not allow for execution of statements between loops: all the action must be in the innermost loop. Thus, Counters are an alternative to equivalent combinatorial algorithms, as are usual in FFTs.

Constructor Summary

Constructors

Constructor and Description
Counter(int d, int[] f, Counter i, FFTPhase p, boolean information) Constructor for class Counter.

Method Summary

Methods

Modifier and Type	Method and Description
Counter	cycleCounters(Counter o, Counter u) Method cycleCounters rearranges the list of counters, moving the innermost one to become the outermost, and keeping the rest in the original order.
int	getFIndex()
int	getTIndex()
int	getTOffset() Make certain parameters accessible from outside: tOffset, tStep, fIndex, tIndex, twiddleReal, and twiddleImag.
int	getTStep()
double[]	getTwiddleImag()
double[]	getTwiddleReal()
void	reset(Counter o) Method reset is another chaining method, which re-initializes all the Counters, setting their loop indices to zero and telling them which is the new outermost one.

Methods inherited from class java.lang.Object

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

Constructor Detail

Counter

public Counter(int d,
       int[] f,
       Counter i,
       FFTPhase p,
       boolean information)

Constructor for class Counter. Only one constructor is provided: supply the total number of dimensions nF of the hyper-matrix, the dimension number d for this counter (ranging from 0 to nF-1), the list f of the sizes of each dimension of the hyper-matrix, the total size n of the input data vector, the counter i that will be nested inside this one, and two vectors of doubles that contain the complex phase factors needed for twiddles.

Method Detail

getTOffset

public int getTOffset()

Make certain parameters accessible from outside: tOffset, tStep, fIndex, tIndex, twiddleReal, and twiddleImag.

getTStep

public int getTStep()

getFIndex

public int getFIndex()

getTIndex

public int getTIndex()

getTwiddleReal

public double[] getTwiddleReal()

getTwiddleImag

public double[] getTwiddleImag()

cycleCounters

public Counter cycleCounters(Counter o,
                    Counter u)

Method cycleCounters rearranges the list of counters, moving the innermost one to become the outermost, and keeping the rest in the original order. It is invoked from the top-most (outer) Counter of the current list, and chains along the list until the method of the innermost Counter is invoked. The method needs arguments o for the outermost Counter before rearrangement, and u for the Counter that is invoking the method. (When it is invoked from outside the outermost Counter, this argument can be set to null. It is not looked at until it is invoked in the innermost Counter.) For each of the outer Counters the method invokes the same method of the next inner Counter, and then it returns the pointer that was returned to it from inside. The innermost Counter uses the method to set up various arrays and to set its pointer to its new inner neighbor, the old outer Counter o. This innermost Counter then returns the pointer to the new innermost Counter, whose pointer it received as an argument when its method was invoked by this Counter. In this way, by invoking the outermost method, one gets in return the pointer to the new outermost method.

reset

public void reset(Counter o)

Method reset is another chaining method, which re-initializes all the Counters, setting their loop indices to zero and telling them which is the new outermost one.