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109 lines
3.3 KiB
109 lines
3.3 KiB
/*
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* QR Code generator library (Java)
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*
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* Copyright (c) Project Nayuki. (MIT License)
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* https://www.nayuki.io/page/qr-code-generator-library
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* - The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* - The Software is provided "as is", without warranty of any kind, express or
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* implied, including but not limited to the warranties of merchantability,
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* fitness for a particular purpose and noninfringement. In no event shall the
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* authors or copyright holders be liable for any claim, damages or other
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* liability, whether in an action of contract, tort or otherwise, arising from,
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* out of or in connection with the Software or the use or other dealings in the
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* Software.
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*/
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package io.nayuki.qrcodegen;
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import java.util.BitSet;
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import java.util.Objects;
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/**
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* An appendable sequence of bits. Bits are packed in big endian within a byte.
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*/
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public final class BitBuffer implements Cloneable {
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/*---- Fields ----*/
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private BitSet data;
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private int bitLength;
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/*---- Constructor ----*/
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// Creates an empty bit buffer (length 0).
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public BitBuffer() {
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data = new BitSet();
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bitLength = 0;
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}
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/*---- Methods ----*/
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// Returns the number of bits in the buffer, which is a non-negative value.
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public int bitLength() {
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return bitLength;
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}
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// Returns the bit at the given index, yielding 0 or 1, or throwing IndexOutOfBoundsException.
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public int getBit(int index) {
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if (index < 0 || index > bitLength)
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throw new IndexOutOfBoundsException();
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return data.get(index) ? 1 : 0;
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}
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// Returns a copy of all bytes, padding up to the nearest byte. Bits are packed in big endian within a byte.
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public byte[] getBytes() {
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byte[] result = new byte[(bitLength + 7) / 8];
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for (int i = 0; i < bitLength; i++)
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result[i >>> 3] |= data.get(i) ? 1 << (7 - (i & 7)) : 0;
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return result;
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}
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// Appends the given number of bits of the given value to this sequence.
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// If 0 <= len <= 31, then this requires 0 <= val < 2^len.
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public void appendBits(int val, int len) {
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if (len < 0 || len > 32 || len < 32 && (val >>> len) != 0)
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throw new IllegalArgumentException("Value out of range");
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for (int i = len - 1; i >= 0; i--, bitLength++) // Append bit by bit
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data.set(bitLength, ((val >>> i) & 1) != 0);
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}
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// Appends the data of the given segment to this bit buffer.
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public void appendData(QrSegment seg) {
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Objects.requireNonNull(seg);
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for (int i = 0; i < seg.bitLength; i++, bitLength++) { // Append bit by bit
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int bit = (seg.getByte(i >>> 3) >>> (7 - (i & 7))) & 1;
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data.set(bitLength, bit != 0);
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}
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}
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// Returns a copy of this bit buffer object.
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public BitBuffer clone() {
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try {
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BitBuffer result = (BitBuffer)super.clone();
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result.data = (BitSet)result.data.clone();
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return result;
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} catch (CloneNotSupportedException e) {
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throw new AssertionError(e);
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}
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}
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}
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