| 1 | // SPDX-FileCopyrightText: 2008 by Jakub Stachowski <qbast@go2.pl> |
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| 2 | // Huffdic decompressor based on Python code by Igor Skochinsky |
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| 3 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 4 | |
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| 5 | #include <QByteArray> |
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| 6 | #include <QtEndian> |
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| 7 | |
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| 8 | namespace Mobipocket |
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| 9 | { |
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| 10 | class BitReader |
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| 11 | { |
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| 12 | public: |
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| 13 | BitReader(QByteArrayView d) |
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| 14 | : len(d.size() * 8) |
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| 15 | , data(d) |
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| 16 | { |
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| 17 | } |
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| 18 | |
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| 19 | quint32 read() |
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| 20 | { |
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| 21 | while (rEndPos - pos < 32) { |
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| 22 | // r does not hold sufficient data, fetch some more |
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| 23 | qint64 bytePos = rEndPos / 8; |
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| 24 | |
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| 25 | if (len - rEndPos >= 32) { |
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| 26 | r <<= 32; |
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| 27 | r |= qFromBigEndian<quint32>(src: data.constData() + bytePos); |
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| 28 | rEndPos += 32; |
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| 29 | break; |
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| 30 | } else if (len - rEndPos > 0) { |
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| 31 | r <<= 8; |
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| 32 | quint8 d = data.at(n: bytePos); |
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| 33 | r |= d; |
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| 34 | rEndPos += 8; |
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| 35 | } else { |
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| 36 | r <<= 8; |
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| 37 | rEndPos += 8; |
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| 38 | } |
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| 39 | } |
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| 40 | |
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| 41 | quint64 t = r << (64 - (rEndPos - pos)); |
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| 42 | return t >> 32; |
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| 43 | } |
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| 44 | |
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| 45 | bool eat(int n) |
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| 46 | { |
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| 47 | pos += n; |
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| 48 | return pos <= len; |
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| 49 | } |
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| 50 | |
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| 51 | int left() |
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| 52 | { |
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| 53 | return len - pos; |
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| 54 | } |
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| 55 | |
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| 56 | private: |
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| 57 | quint64 r = 0; |
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| 58 | int pos = 0; |
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| 59 | int len = 0; |
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| 60 | int rEndPos = 0; //< position past the LSB of r |
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| 61 | QByteArrayView data; |
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| 62 | }; |
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| 63 | } // namespace Mobipocket |
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| 64 | |
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