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72 lines
1.8 KiB
72 lines
1.8 KiB
/* |
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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 peek at |
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* @return int representing the bits peeked at. 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 peekBits(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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