mirror of
https://github.com/octoleo/plantuml.git
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247 lines
6.7 KiB
Java
247 lines
6.7 KiB
Java
/*
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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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/**
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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 {
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// TODO: I have changed these members to be public so ProGuard can inline get() and set(). Ideally
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// they'd be private and we'd use the -allowaccessmodification flag, but Dalvik rejects the
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// resulting binary at runtime on Android. If we find a solution to this, these should be changed
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// back to private.
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public int[] bits;
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public 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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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) >> 3;
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}
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private void ensureCapacity(int size) {
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if (size > bits.length << 5) {
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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 >> 5] & (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 >> 5] |= 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 >> 5] ^= 1 << (i & 0x1F);
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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 >> 5] = newBits;
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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 or equal to start
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*/
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public boolean isRange(int start, int end, boolean value) {
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if (end < start) {
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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 >> 5;
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int lastInt = end >> 5;
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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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int mask;
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if (firstBit == 0 && lastBit == 31) {
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mask = -1;
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} else {
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mask = 0;
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for (int j = firstBit; j <= lastBit; j++) {
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mask |= 1 << j;
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}
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}
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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 >> 5] |= (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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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.getSize();
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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 (bits.length != other.bits.length) {
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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 byte could be incomplete (i.e. not have 8 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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int size = this.size;
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for (int i = 0; i < size; i++) {
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if (get(size - i - 1)) {
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newBits[i >> 5] |= 1 << (i & 0x1F);
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}
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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) >> 5];
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}
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public String toString() {
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StringBuffer result = new StringBuffer(size);
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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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} |