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