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QR-Code-generator/src/io/nayuki/fastqrcodegen/BitBuffer.java

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/*
* Fast QR Code generator library
*
* Copyright (c) Project Nayuki. (MIT License)
* https://www.nayuki.io/
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
* - The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* - The Software is provided "as is", without warranty of any kind, express or
* implied, including but not limited to the warranties of merchantability,
* fitness for a particular purpose and noninfringement. In no event shall the
* authors or copyright holders be liable for any claim, damages or other
* liability, whether in an action of contract, tort or otherwise, arising from,
* out of or in connection with the Software or the use or other dealings in the
* Software.
*/
package io.nayuki.fastqrcodegen;
import java.util.Arrays;
final class BitBuffer {
/*---- Fields ----*/
private int[] data;
private int bitLength;
/*---- Constructors ----*/
public BitBuffer() {
data = new int[64];
bitLength = 0;
}
/*---- Methods ----*/
public int getBit(int index) {
if (index < 0 || index >= bitLength)
throw new IndexOutOfBoundsException();
return (data[index >>> 5] >>> ~index) & 1;
}
public void appendBits(int val, int len) {
if (len < 0 || len > 31 || val >>> len != 0)
throw new IllegalArgumentException("Value out of range");
if (bitLength + len + 1 > data.length << 5)
data = Arrays.copyOf(data, data.length * 2);
assert bitLength + len <= data.length << 5;
int remain = 32 - (bitLength & 0x1F);
assert 1 <= remain && remain <= 32;
if (remain < len) {
data[bitLength >>> 5] |= val >>> (len - remain);
bitLength += remain;
assert (bitLength & 0x1F) == 0;
len -= remain;
val &= (1 << len) - 1;
remain = 32;
}
data[bitLength >>> 5] |= val << (remain - len);
bitLength += len;
}
}