--- /dev/null 2015-11-23 13:25:20.000000000 -0800 +++ new/src/java.desktop/share/classes/sun/java2d/marlin/MergeSort.java 2015-11-23 13:25:20.000000000 -0800 @@ -0,0 +1,177 @@ +/* + * Copyright (c) 2009, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +package sun.java2d.marlin; + +/** + * MergeSort adapted from (OpenJDK 8) java.util.Array.legacyMergeSort(Object[]) + * to swap two arrays at the same time (x & y) + * and use external auxiliary storage for temporary arrays + */ +final class MergeSort { + + // insertion sort threshold + public static final int INSERTION_SORT_THRESHOLD = 14; + + /** + * Modified merge sort: + * Input arrays are in both auxX/auxY (sorted: 0 to insertionSortIndex) + * and x/y (unsorted: insertionSortIndex to toIndex) + * Outputs are stored in x/y arrays + */ + static void mergeSortNoCopy(final int[] x, final int[] y, + final int[] auxX, final int[] auxY, + final int toIndex, + final int insertionSortIndex) + { + if ((toIndex > x.length) || (toIndex > y.length) + || (toIndex > auxX.length) || (toIndex > auxY.length)) { + // explicit check to avoid bound checks within hot loops (below): + throw new ArrayIndexOutOfBoundsException("bad arguments: toIndex=" + + toIndex); + } + + // sort second part only using merge / insertion sort + // in auxiliary storage (auxX/auxY) + mergeSort(x, y, x, auxX, y, auxY, insertionSortIndex, toIndex); + + // final pass to merge both + // Merge sorted parts (auxX/auxY) into x/y arrays + if ((insertionSortIndex == 0) + || (auxX[insertionSortIndex - 1] <= auxX[insertionSortIndex])) { +// System.out.println("mergeSortNoCopy: ordered"); + // 34 occurences + // no initial left part or both sublists (auxX, auxY) are sorted: + // copy back data into (x, y): + System.arraycopy(auxX, 0, x, 0, toIndex); + System.arraycopy(auxY, 0, y, 0, toIndex); + return; + } + + for (int i = 0, p = 0, q = insertionSortIndex; i < toIndex; i++) { + if ((q >= toIndex) || ((p < insertionSortIndex) + && (auxX[p] <= auxX[q]))) { + x[i] = auxX[p]; + y[i] = auxY[p]; + p++; + } else { + x[i] = auxX[q]; + y[i] = auxY[q]; + q++; + } + } + } + + /** + * Src is the source array that starts at index 0 + * Dest is the (possibly larger) array destination with a possible offset + * low is the index in dest to start sorting + * high is the end index in dest to end sorting + */ + private static void mergeSort(final int[] refX, final int[] refY, + final int[] srcX, final int[] dstX, + final int[] srcY, final int[] dstY, + final int low, final int high) + { + final int length = high - low; + + /* + * Tuning parameter: list size at or below which insertion sort + * will be used in preference to mergesort. + */ + if (length <= INSERTION_SORT_THRESHOLD) { + // Insertion sort on smallest arrays + dstX[low] = refX[low]; + dstY[low] = refY[low]; + + for (int i = low + 1, j = low, x, y; i < high; j = i++) { + x = refX[i]; + y = refY[i]; + + while (dstX[j] > x) { + // swap element + dstX[j + 1] = dstX[j]; + dstY[j + 1] = dstY[j]; + if (j-- == low) { + break; + } + } + dstX[j + 1] = x; + dstY[j + 1] = y; + } + return; + } + + // Recursively sort halves of dest into src + + // note: use signed shift (not >>>) for performance + // as indices are small enough to exceed Integer.MAX_VALUE + final int mid = (low + high) >> 1; + + mergeSort(refX, refY, dstX, srcX, dstY, srcY, low, mid); + mergeSort(refX, refY, dstX, srcX, dstY, srcY, mid, high); + + // If arrays are inverted ie all(A) > all(B) do swap A and B to dst + if (srcX[high - 1] <= srcX[low]) { +// System.out.println("mergeSort: inverse ordered"); + // 1561 occurences + final int left = mid - low; + final int right = high - mid; + final int off = (left != right) ? 1 : 0; + // swap parts: + System.arraycopy(srcX, low, dstX, mid + off, left); + System.arraycopy(srcX, mid, dstX, low, right); + System.arraycopy(srcY, low, dstY, mid + off, left); + System.arraycopy(srcY, mid, dstY, low, right); + return; + } + + // If arrays are already sorted, just copy from src to dest. This is an + // optimization that results in faster sorts for nearly ordered lists. + if (srcX[mid - 1] <= srcX[mid]) { +// System.out.println("mergeSort: ordered"); + // 14 occurences + System.arraycopy(srcX, low, dstX, low, length); + System.arraycopy(srcY, low, dstY, low, length); + return; + } + + // Merge sorted halves (now in src) into dest + for (int i = low, p = low, q = mid; i < high; i++) { + if ((q >= high) || ((p < mid) && (srcX[p] <= srcX[q]))) { + dstX[i] = srcX[p]; + dstY[i] = srcY[p]; + p++; + } else { + dstX[i] = srcX[q]; + dstY[i] = srcY[q]; + q++; + } + } + } + + private MergeSort() { + } +}