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Fast number theoretic transform implementation using Aparapi
There is a newer version: 1.14.0
/*
 * MIT License
 *
 * Copyright (c) 2002-2021 Mikko Tommila
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.apfloat.aparapi;

import org.apfloat.ApfloatRuntimeException;
import org.apfloat.spi.ArrayAccess;
import org.apfloat.internal.IntNTTStepStrategy;
import org.apfloat.internal.IntWTables;
import org.apfloat.internal.Scramble;

import static org.apfloat.internal.IntModConstants.*;

/**
 * NTT steps for the int element type aparapi transforms.
 *
 * @since 1.8.3
 * @version 1.8.3
 * @author Mikko Tommila
 */

public class IntAparapiNTTStepStrategy
    extends IntNTTStepStrategy
{
    /**
     * Default constructor.
     */

    public IntAparapiNTTStepStrategy()
    {
    }

    @Override
    public void multiplyElements(ArrayAccess arrayAccess, int startRow, int startColumn, int rows, int columns, long length, long totalTransformLength, boolean isInverse, int modulus)
        throws ApfloatRuntimeException
    {
        setModulus(MODULUS[modulus]);
        int w = (isInverse ?
                 getInverseNthRoot(PRIMITIVE_ROOT[modulus], length) :
                 getForwardNthRoot(PRIMITIVE_ROOT[modulus], length));
        int scaleFactor = (isInverse ?
                           modDivide((int) 1, (int) totalTransformLength) :
                           (int) 1);

        IntKernel kernel = IntKernel.getInstance();
        kernel.setOp(IntKernel.MULTIPLY_ELEMENTS);
        kernel.setArrayAccess(arrayAccess);
        kernel.setStartRow(startRow);
        kernel.setStartColumn(startColumn);
        kernel.setRows(rows);
        kernel.setColumns(columns);
        kernel.setW(w);
        kernel.setScaleFactor(scaleFactor);
        kernel.setModulus(MODULUS[modulus]);

        kernel.execute(columns);
    }

    /**
     * Transform the columns of the data matrix. Note that this method expects the data
     * to be organized in columns, not rows. The arguments length and
     * count still mean the length of one transform and number of transforms
     * to be done.
     *
     * @param arrayAccess The memory array to split to columns and to transform.
     * @param length Length of one transform (one columns).
     * @param count Number of columns.
     * @param isInverse true if an inverse transform is performed, false if a forward transform is performed.
     * @param permute If permutation should be done.
     * @param modulus Index of the modulus.
     */

    @Override
    public void transformRows(ArrayAccess arrayAccess, int length, int count, boolean isInverse, boolean permute, int modulus)
        throws ApfloatRuntimeException
    {
        int[] wTable = (isInverse ?
                        IntWTables.getInverseWTable(modulus, length) :
                        IntWTables.getWTable(modulus, length));
        int[] permutationTable = (permute ? Scramble.createScrambleTable(length) : null);

        IntKernel kernel = IntKernel.getInstance();
        kernel.setOp(isInverse ? IntKernel.INVERSE_TRANSFORM_ROWS : IntKernel.TRANSFORM_ROWS);
        kernel.setLength(length);
        kernel.setArrayAccess(arrayAccess);
        kernel.setWTable(wTable);
        kernel.setPermutationTable(permutationTable);
        kernel.setModulus(MODULUS[modulus]);

        kernel.put(wTable);
        if (permutationTable != null)
        {
            kernel.put(permutationTable);
        }

        kernel.execute(count);
    }
}