org.apfloat.internal.DoubleScramble Maven / Gradle / Ivy
/*
* MIT License
*
* Copyright (c) 2002-2023 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.internal;
/**
* Functions to perform bit-reverse ordering of double data.
*
* @version 1.0
* @author Mikko Tommila
*/
public class DoubleScramble
{
private DoubleScramble()
{
}
/**
* Permute the data in the table to bit-reversed order.
*
* The permutation table argument should contain pairs of indexes
* that indicate array elements whose contents are swapped.
*
* @param data The array to permute.
* @param offset The offset within the array to permute.
* @param permutationTable Table of indexes indicating, which elements in the data are to be swapped.
*/
public static void scramble(double[] data, int offset, int[] permutationTable)
{
for (int k = 0; k < permutationTable.length; k += 2)
{
int i = offset + permutationTable[k],
j = offset + permutationTable[k + 1];
double tmp = data[i];
data[i] = data[j];
data[j] = tmp;
}
}
}