mirror of https://github.com/NekoX-Dev/NekoX.git
358 lines
9.9 KiB
Java
Executable File
358 lines
9.9 KiB
Java
Executable File
/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.zxing.common;
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import java.util.Arrays;
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/**
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* <p>A simple, fast array of bits, represented compactly by an array of ints internally.</p>
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*
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* @author Sean Owen
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*/
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public final class BitArray implements Cloneable {
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private int[] bits;
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private int size;
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public BitArray() {
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this.size = 0;
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this.bits = new int[1];
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}
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public BitArray(int size) {
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this.size = size;
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this.bits = makeArray(size);
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}
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// For testing only
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BitArray(int[] bits, int size) {
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this.bits = bits;
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this.size = size;
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}
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public int getSize() {
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return size;
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}
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public int getSizeInBytes() {
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return (size + 7) / 8;
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}
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private void ensureCapacity(int size) {
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if (size > bits.length * 32) {
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int[] newBits = makeArray(size);
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System.arraycopy(bits, 0, newBits, 0, bits.length);
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this.bits = newBits;
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}
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}
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/**
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* @param i bit to get
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* @return true iff bit i is set
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*/
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public boolean get(int i) {
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return (bits[i / 32] & (1 << (i & 0x1F))) != 0;
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}
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/**
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* Sets bit i.
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*
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* @param i bit to set
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*/
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public void set(int i) {
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bits[i / 32] |= 1 << (i & 0x1F);
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}
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/**
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* Flips bit i.
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*
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* @param i bit to set
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*/
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public void flip(int i) {
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bits[i / 32] ^= 1 << (i & 0x1F);
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}
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/**
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* @param from first bit to check
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* @return index of first bit that is set, starting from the given index, or size if none are set
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* at or beyond this given index
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* @see #getNextUnset(int)
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*/
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public int getNextSet(int from) {
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if (from >= size) {
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return size;
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}
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int bitsOffset = from / 32;
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int currentBits = bits[bitsOffset];
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// mask off lesser bits first
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currentBits &= -(1 << (from & 0x1F));
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while (currentBits == 0) {
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if (++bitsOffset == bits.length) {
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return size;
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}
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currentBits = bits[bitsOffset];
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}
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int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits);
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return Math.min(result, size);
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}
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/**
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* @param from index to start looking for unset bit
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* @return index of next unset bit, or {@code size} if none are unset until the end
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* @see #getNextSet(int)
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*/
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public int getNextUnset(int from) {
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if (from >= size) {
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return size;
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}
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int bitsOffset = from / 32;
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int currentBits = ~bits[bitsOffset];
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// mask off lesser bits first
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currentBits &= -(1 << (from & 0x1F));
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while (currentBits == 0) {
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if (++bitsOffset == bits.length) {
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return size;
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}
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currentBits = ~bits[bitsOffset];
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}
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int result = (bitsOffset * 32) + Integer.numberOfTrailingZeros(currentBits);
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return Math.min(result, size);
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}
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/**
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* Sets a block of 32 bits, starting at bit i.
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*
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* @param i first bit to set
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* @param newBits the new value of the next 32 bits. Note again that the least-significant bit
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* corresponds to bit i, the next-least-significant to i+1, and so on.
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*/
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public void setBulk(int i, int newBits) {
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bits[i / 32] = newBits;
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}
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/**
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* Sets a range of bits.
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*
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* @param start start of range, inclusive.
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* @param end end of range, exclusive
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*/
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public void setRange(int start, int end) {
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if (end < start || start < 0 || end > size) {
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throw new IllegalArgumentException();
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}
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if (end == start) {
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return;
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}
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end--; // will be easier to treat this as the last actually set bit -- inclusive
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int firstInt = start / 32;
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int lastInt = end / 32;
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for (int i = firstInt; i <= lastInt; i++) {
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int firstBit = i > firstInt ? 0 : start & 0x1F;
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int lastBit = i < lastInt ? 31 : end & 0x1F;
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// Ones from firstBit to lastBit, inclusive
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int mask = (2 << lastBit) - (1 << firstBit);
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bits[i] |= mask;
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}
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}
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/**
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* Clears all bits (sets to false).
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*/
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public void clear() {
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int max = bits.length;
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for (int i = 0; i < max; i++) {
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bits[i] = 0;
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}
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}
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/**
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* Efficient method to check if a range of bits is set, or not set.
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*
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* @param start start of range, inclusive.
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* @param end end of range, exclusive
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* @param value if true, checks that bits in range are set, otherwise checks that they are not set
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* @return true iff all bits are set or not set in range, according to value argument
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* @throws IllegalArgumentException if end is less than start or the range is not contained in the array
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*/
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public boolean isRange(int start, int end, boolean value) {
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if (end < start || start < 0 || end > size) {
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throw new IllegalArgumentException();
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}
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if (end == start) {
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return true; // empty range matches
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}
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end--; // will be easier to treat this as the last actually set bit -- inclusive
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int firstInt = start / 32;
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int lastInt = end / 32;
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for (int i = firstInt; i <= lastInt; i++) {
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int firstBit = i > firstInt ? 0 : start & 0x1F;
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int lastBit = i < lastInt ? 31 : end & 0x1F;
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// Ones from firstBit to lastBit, inclusive
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int mask = (2 << lastBit) - (1 << firstBit);
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// Return false if we're looking for 1s and the masked bits[i] isn't all 1s (that is,
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// equals the mask, or we're looking for 0s and the masked portion is not all 0s
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if ((bits[i] & mask) != (value ? mask : 0)) {
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return false;
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}
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}
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return true;
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}
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public void appendBit(boolean bit) {
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ensureCapacity(size + 1);
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if (bit) {
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bits[size / 32] |= 1 << (size & 0x1F);
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}
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size++;
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}
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/**
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* Appends the least-significant bits, from value, in order from most-significant to
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* least-significant. For example, appending 6 bits from 0x000001E will append the bits
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* 0, 1, 1, 1, 1, 0 in that order.
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*
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* @param value {@code int} containing bits to append
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* @param numBits bits from value to append
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*/
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public void appendBits(int value, int numBits) {
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if (numBits < 0 || numBits > 32) {
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throw new IllegalArgumentException("Num bits must be between 0 and 32");
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}
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ensureCapacity(size + numBits);
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for (int numBitsLeft = numBits; numBitsLeft > 0; numBitsLeft--) {
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appendBit(((value >> (numBitsLeft - 1)) & 0x01) == 1);
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}
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}
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public void appendBitArray(BitArray other) {
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int otherSize = other.size;
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ensureCapacity(size + otherSize);
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for (int i = 0; i < otherSize; i++) {
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appendBit(other.get(i));
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}
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}
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public void xor(BitArray other) {
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if (size != other.size) {
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throw new IllegalArgumentException("Sizes don't match");
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}
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for (int i = 0; i < bits.length; i++) {
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// The last int could be incomplete (i.e. not have 32 bits in
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// it) but there is no problem since 0 XOR 0 == 0.
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bits[i] ^= other.bits[i];
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}
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}
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/**
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*
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* @param bitOffset first bit to start writing
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* @param array array to write into. Bytes are written most-significant byte first. This is the opposite
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* of the internal representation, which is exposed by {@link #getBitArray()}
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* @param offset position in array to start writing
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* @param numBytes how many bytes to write
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*/
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public void toBytes(int bitOffset, byte[] array, int offset, int numBytes) {
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for (int i = 0; i < numBytes; i++) {
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int theByte = 0;
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for (int j = 0; j < 8; j++) {
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if (get(bitOffset)) {
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theByte |= 1 << (7 - j);
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}
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bitOffset++;
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}
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array[offset + i] = (byte) theByte;
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}
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}
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/**
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* @return underlying array of ints. The first element holds the first 32 bits, and the least
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* significant bit is bit 0.
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*/
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public int[] getBitArray() {
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return bits;
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}
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/**
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* Reverses all bits in the array.
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*/
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public void reverse() {
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int[] newBits = new int[bits.length];
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// reverse all int's first
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int len = (size - 1) / 32;
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int oldBitsLen = len + 1;
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for (int i = 0; i < oldBitsLen; i++) {
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long x = bits[i];
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x = ((x >> 1) & 0x55555555L) | ((x & 0x55555555L) << 1);
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x = ((x >> 2) & 0x33333333L) | ((x & 0x33333333L) << 2);
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x = ((x >> 4) & 0x0f0f0f0fL) | ((x & 0x0f0f0f0fL) << 4);
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x = ((x >> 8) & 0x00ff00ffL) | ((x & 0x00ff00ffL) << 8);
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x = ((x >> 16) & 0x0000ffffL) | ((x & 0x0000ffffL) << 16);
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newBits[len - i] = (int) x;
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}
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// now correct the int's if the bit size isn't a multiple of 32
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if (size != oldBitsLen * 32) {
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int leftOffset = oldBitsLen * 32 - size;
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int currentInt = newBits[0] >>> leftOffset;
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for (int i = 1; i < oldBitsLen; i++) {
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int nextInt = newBits[i];
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currentInt |= nextInt << (32 - leftOffset);
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newBits[i - 1] = currentInt;
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currentInt = nextInt >>> leftOffset;
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}
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newBits[oldBitsLen - 1] = currentInt;
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}
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bits = newBits;
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}
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private static int[] makeArray(int size) {
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return new int[(size + 31) / 32];
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}
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@Override
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public boolean equals(Object o) {
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if (!(o instanceof BitArray)) {
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return false;
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}
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BitArray other = (BitArray) o;
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return size == other.size && Arrays.equals(bits, other.bits);
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}
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@Override
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public int hashCode() {
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return 31 * size + Arrays.hashCode(bits);
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}
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@Override
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public String toString() {
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StringBuilder result = new StringBuilder(size + (size / 8) + 1);
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for (int i = 0; i < size; i++) {
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if ((i & 0x07) == 0) {
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result.append(' ');
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}
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result.append(get(i) ? 'X' : '.');
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}
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return result.toString();
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}
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@Override
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public BitArray clone() {
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return new BitArray(bits.clone(), size);
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}
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}
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