com.itextpdf.text.pdf.qrcode.BitArray Maven / Gradle / Ivy
/*
* Copyright 2007 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.itextpdf.text.pdf.qrcode;
/**
* A simple, fast array of bits, represented compactly by an array of ints internally.
*
* @author Sean Owen
* @since 5.0.2
*/
public final class BitArray {
// TODO: I have changed these members to be public so ProGuard can inline get() and set(). Ideally
// they'd be private and we'd use the -allowaccessmodification flag, but Dalvik rejects the
// resulting binary at runtime on Android. If we find a solution to this, these should be changed
// back to private.
public int[] bits;
public final int size;
public BitArray(int size) {
if (size < 1) {
throw new IllegalArgumentException("size must be at least 1");
}
this.size = size;
this.bits = makeArray(size);
}
public int getSize() {
return size;
}
/**
* @param i bit to get
* @return true iff bit i is set
*/
public boolean get(int i) {
return (bits[i >> 5] & (1 << (i & 0x1F))) != 0;
}
/**
* Sets bit i.
*
* @param i bit to set
*/
public void set(int i) {
bits[i >> 5] |= 1 << (i & 0x1F);
}
/**
* Flips bit i.
*
* @param i bit to set
*/
public void flip(int i) {
bits[i >> 5] ^= 1 << (i & 0x1F);
}
/**
* Sets a block of 32 bits, starting at bit i.
*
* @param i first bit to set
* @param newBits the new value of the next 32 bits. Note again that the least-significant bit
* corresponds to bit i, the next-least-significant to i+1, and so on.
*/
public void setBulk(int i, int newBits) {
bits[i >> 5] = newBits;
}
/**
* Clears all bits (sets to false).
*/
public void clear() {
int max = bits.length;
for (int i = 0; i < max; i++) {
bits[i] = 0;
}
}
/**
* Efficient method to check if a range of bits is set, or not set.
*
* @param start start of range, inclusive.
* @param end end of range, exclusive
* @param value if true, checks that bits in range are set, otherwise checks that they are not set
* @return true iff all bits are set or not set in range, according to value argument
* @throws IllegalArgumentException if end is less than or equal to start
*/
public boolean isRange(int start, int end, boolean value) {
if (end < start) {
throw new IllegalArgumentException();
}
if (end == start) {
return true; // empty range matches
}
end--; // will be easier to treat this as the last actually set bit -- inclusive
int firstInt = start >> 5;
int lastInt = end >> 5;
for (int i = firstInt; i <= lastInt; i++) {
int firstBit = i > firstInt ? 0 : start & 0x1F;
int lastBit = i < lastInt ? 31 : end & 0x1F;
int mask;
if (firstBit == 0 && lastBit == 31) {
mask = -1;
} else {
mask = 0;
for (int j = firstBit; j <= lastBit; j++) {
mask |= 1 << j;
}
}
// Return false if we're looking for 1s and the masked bits[i] isn't all 1s (that is,
// equals the mask, or we're looking for 0s and the masked portion is not all 0s
if ((bits[i] & mask) != (value ? mask : 0)) {
return false;
}
}
return true;
}
/**
* @return underlying array of ints. The first element holds the first 32 bits, and the least
* significant bit is bit 0.
*/
public int[] getBitArray() {
return bits;
}
/**
* Reverses all bits in the array.
*/
public void reverse() {
int[] newBits = new int[bits.length];
int size = this.size;
for (int i = 0; i < size; i++) {
if (get(size - i - 1)) {
newBits[i >> 5] |= 1 << (i & 0x1F);
}
}
bits = newBits;
}
private static int[] makeArray(int size) {
int arraySize = size >> 5;
if ((size & 0x1F) != 0) {
arraySize++;
}
return new int[arraySize];
}
public String toString() {
StringBuffer result = new StringBuffer(size);
for (int i = 0; i < size; i++) {
if ((i & 0x07) == 0) {
result.append(' ');
}
result.append(get(i) ? 'X' : '.');
}
return result.toString();
}
}