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/*
* Copyright 2016 Nu-book Inc.
* Copyright 2016 ZXing authors
*/
// SPDX-License-Identifier: Apache-2.0
#pragma once
namespace ZXing {
class ByteArray;
/**
* <p>This provides an easy abstraction to read bits at a time from a sequence of bytes, where the
* number of bits read is not often a multiple of 8.</p>
*
* <p>This class is thread-safe but not reentrant -- unless the caller modifies the bytes array
* it passed in, in which case all bets are off.</p>
*
* @author Sean Owen
*/
class BitSource
{
const ByteArray& _bytes;
int _byteOffset = 0;
int _bitOffset = 0;
public:
/**
* @param bytes bytes from which this will read bits. Bits will be read from the first byte first.
* Bits are read within a byte from most-significant to least-significant bit.
* IMPORTANT: Bit source DOES NOT copy data byte, thus make sure that the bytes outlive the bit source object.
*/
explicit BitSource(const ByteArray& bytes) : _bytes(bytes) {}
BitSource(BitSource &) = delete;
BitSource& operator=(const BitSource &) = delete;
/**
* @return index of next bit in current byte which would be read by the next call to {@link #readBits(int)}.
*/
int bitOffset() const {
return _bitOffset;
}
/**
* @return index of next byte in input byte array which would be read by the next call to {@link #readBits(int)}.
*/
int byteOffset() const {
return _byteOffset;
}
/**
* @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
*/
int readBits(int numBits);
/**
* @param numBits number of bits to peek at
* @return int representing the bits peeked at. The bits will appear as the least-significant
* bits of the int
*/
int peekBits(int numBits) const;
/**
* @return number of bits that can be read successfully
*/
int available() const;
};
} // ZXing