de.uniks.networkparser.bytes.qr.BitArray Maven / Gradle / Ivy
/*
* Copyright 2008 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 de.uniks.networkparser.bytes.qr;
import java.util.Arrays;
/**
*
* A simple, fast array of bits, represented compactly by an array of ints
* internally.
*
*
* @author Sean Owen
*/
final class BitArray implements Cloneable {
private int[] bits;
private int size;
private int byteOffset;
private int bitOffset;
BitArray() {
this.size = 0;
this.bits = new int[1];
}
BitArray(int size) {
this.size = size;
this.bits = makeArray(size);
}
BitArray(byte[] bytes) {
if(bytes == null) {
return;
}
size = bytes.length;
this.bits = new int[size];
for(int i=0;i bits.length * 32) {
int[] newBits = makeArray(size);
System.arraycopy(bits, 0, newBits, 0, bits.length);
this.bits = newBits;
}
}
/**
* @param i bit to get
* @return true iff bit i is set
*/
public boolean get(int i) {
return (bits[i / 32] & (1 << (i & 0x1F))) != 0;
}
/**
* Sets bit i.
*
* @param i bit to set
*/
public void set(int i) {
bits[i / 32] |= 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.
*/
void setBulk(int i, int newBits) {
bits[i / 32] = newBits;
}
/** Clears all bits (sets to false). */
public void clear() {
int max = bits.length;
for (int i = 0; i < max; i++) {
bits[i] = 0;
}
}
void appendBit(boolean bit) {
ensureCapacity(size + 1);
if (bit) {
bits[size / 32] |= 1 << (size & 0x1F);
}
size++;
}
/**
* Appends the least-significant bits, from value, in order from
* most-significant to least-significant. For example, appending 6 bits from
* 0x000001E will append the bits 0, 1, 1, 1, 1, 0 in that order.
*
* @param value {@code int} containing bits to append
* @param numBits bits from value to append
*/
void appendBits(int value, int numBits) {
if (numBits < 0 || numBits > 32) {
throw new IllegalArgumentException("Num bits must be between 0 and 32");
}
ensureCapacity(size + numBits);
for (int numBitsLeft = numBits; numBitsLeft > 0; numBitsLeft--) {
appendBit(((value >> (numBitsLeft - 1)) & 0x01) == 1);
}
}
void appendBitArray(BitArray other) {
int otherSize = other.size;
ensureCapacity(size + otherSize);
for (int i = 0; i < otherSize; i++) {
appendBit(other.get(i));
}
}
void xor(BitArray other) {
if (bits.length != other.bits.length) {
throw new IllegalArgumentException("Sizes don't match");
}
for (int i = 0; i < bits.length; i++) {
// The last byte could be incomplete (i.e. not have 8 bits in
// it) but there is no problem since 0 XOR 0 == 0.
bits[i] ^= other.bits[i];
}
}
/**
*
* @param bitOffset first bit to start writing
* @param array array to write into. Bytes are written most-significant byte first. This is the opposite of the internal representation,
* which is exposed by {@link #getBitArray()}
* @param offset position in array to start writing
* @param numBytes how many bytes to write
*/
void toBytes(int bitOffset, byte[] array, int offset, int numBytes) {
for (int i = 0; i < numBytes; i++) {
int theByte = 0;
for (int j = 0; j < 8; j++) {
if (get(bitOffset)) {
theByte |= 1 << (7 - j);
}
bitOffset++;
}
array[offset + i] = (byte) theByte;
}
}
/**
* @return underlying array of ints. The first element holds the first 32 bits, and the least significant bit is bit 0.
*/
int[] getBitArray() {
return bits;
}
/**
* Reverses all bits in the array.
*/
void reverse() {
int[] newBits = new int[bits.length];
// reverse all int's first
int len = (size - 1) / 32;
int oldBitsLen = len + 1;
for (int i = 0; i < oldBitsLen; i++) {
long x = (long) bits[i];
x = ((x >> 1) & 0x55555555L) | ((x & 0x55555555L) << 1);
x = ((x >> 2) & 0x33333333L) | ((x & 0x33333333L) << 2);
x = ((x >> 4) & 0x0f0f0f0fL) | ((x & 0x0f0f0f0fL) << 4);
x = ((x >> 8) & 0x00ff00ffL) | ((x & 0x00ff00ffL) << 8);
x = ((x >> 16) & 0x0000ffffL) | ((x & 0x0000ffffL) << 16);
newBits[len - i] = (byte) x;
}
// now correct the int's if the bit size isn't a multiple of 32
if (size != oldBitsLen * 32) {
int leftOffset = oldBitsLen * 32 - size;
int mask = 1;
for (int i = 0; i < 31 - leftOffset; i++) {
mask = (mask << 1) | 1;
}
int currentInt = (newBits[0] >> leftOffset) & mask;
for (int i = 1; i < oldBitsLen; i++) {
int nextInt = newBits[i];
currentInt |= nextInt << (32 - leftOffset);
newBits[i - 1] = (byte) currentInt;
currentInt = (nextInt >> leftOffset) & mask;
}
newBits[oldBitsLen - 1] = (byte) currentInt;
}
bits = newBits;
}
private static int[] makeArray(int size) {
return new int[(size + 31) / 32];
}
@Override
public boolean equals(Object o) {
if (!(o instanceof BitArray)) {
return false;
}
BitArray other = (BitArray) o;
return size == other.size && Arrays.equals(bits, other.bits);
}
@Override
public int hashCode() {
return 31 * size + Arrays.hashCode(bits);
}
@Override
public String toString() {
StringBuilder result = new StringBuilder(size);
for (int i = 0; i < size; i++) {
if ((i & 0x07) == 0) {
result.append(' ');
}
result.append(get(i) ? 'X' : '.');
}
return result.toString();
}
@Override
public BitArray clone() {
return new BitArray(bits.clone(), size);
}
/**
* @return number of bits that can be read successfully
*/
int available() {
return 8 * (bits.length - byteOffset) - bitOffset;
}
/**
* @param numBits number of bits to read
* @return int representing the bits read. The bits will appear as the least-significant bits of the int
* @throws IllegalArgumentException if numBits isn't in [1,32] or more than is available
*/
int readBits(int numBits) {
if (numBits < 1 || numBits > 32 || numBits > available()) {
throw new IllegalArgumentException(String.valueOf(numBits));
}
int result = 0;
// First, read remainder from current byte
if (bitOffset > 0) {
int bitsLeft = 8 - bitOffset;
int toRead = numBits < bitsLeft ? numBits : bitsLeft;
int bitsToNotRead = bitsLeft - toRead;
int mask = (0xFF >> (8 - toRead)) << bitsToNotRead;
result = (bits[byteOffset] & mask) >> bitsToNotRead;
numBits -= toRead;
bitOffset += toRead;
if (bitOffset == 8) {
bitOffset = 0;
byteOffset++;
}
}
// Next read whole bytes
if (numBits > 0) {
while (numBits >= 8) {
result = (result << 8) | (bits[byteOffset] & 0xFF);
byteOffset++;
numBits -= 8;
}
// Finally read a partial byte
if (numBits > 0) {
int bitsToNotRead = 8 - numBits;
int mask = (0xFF >> bitsToNotRead) << bitsToNotRead;
result = (result << numBits) | ((bits[byteOffset] & mask) >> bitsToNotRead);
bitOffset += numBits;
}
}
return result;
}
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