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| |
| #ifndef BITSTREAMS_P_H |
| #define BITSTREAMS_P_H |
| |
| // |
| // W A R N I N G |
| // ------------- |
| // |
| // This file is not part of the Qt API. It exists for the convenience |
| // of other Qt classes. This header file may change from version to |
| // version without notice, or even be removed. |
| // |
| // We mean it. |
| // |
| |
| #include <QtCore/qglobal.h> |
| #include <QtCore/qdebug.h> |
| |
| #include <type_traits> |
| #include <algorithm> |
| #include <vector> |
| |
| QT_BEGIN_NAMESPACE |
| |
| class QByteArray; |
| |
| namespace HPack |
| { |
| |
| // BitOStream works with an external buffer, |
| // for example, HEADERS frame. |
| class Q_AUTOTEST_EXPORT BitOStream |
| { |
| public: |
| BitOStream(std::vector<uchar> &buffer); |
| |
| // Write 'bitLength' bits from the least significant |
| // bits in 'bits' to bitstream: |
| void writeBits(uchar bits, quint8 bitLength); |
| // HPACK data format, we support: |
| // * 32-bit integers |
| // * strings |
| void write(quint32 src); |
| void write(const QByteArray &src, bool compressed); |
| |
| quint64 bitLength() const; |
| quint64 byteLength() const; |
| const uchar *begin() const; |
| const uchar *end() const; |
| |
| void clear(); |
| |
| private: |
| Q_DISABLE_COPY_MOVE(BitOStream); |
| |
| std::vector<uchar> &buffer; |
| quint64 bitsSet; |
| }; |
| |
| class Q_AUTOTEST_EXPORT BitIStream |
| { |
| public: |
| // Error is set by 'read' functions. |
| // 'peek' does not set the error, |
| // since it just peeks some bits |
| // without the notion of wrong/right. |
| // 'read' functions only change 'streamOffset' |
| // on success. |
| enum class Error |
| { |
| NoError, |
| NotEnoughData, |
| CompressionError, |
| InvalidInteger |
| }; |
| |
| BitIStream(); |
| BitIStream(const uchar *f, const uchar *l); |
| |
| quint64 bitLength() const; |
| bool hasMoreBits() const; |
| |
| // peekBits tries to read 'length' bits from the bitstream into |
| // 'dst' ('length' must be <= sizeof(dst) * 8), packing them |
| // starting from the most significant bit of the most significant |
| // byte. It's a template so that we can use it with different |
| // integer types. Returns the number of bits actually read. |
| // Does not change stream's offset. |
| |
| template<class T> |
| quint64 peekBits(quint64 from, quint64 length, T *dstPtr) const |
| { |
| static_assert(std::is_unsigned<T>::value, "peekBits: unsigned integer type expected"); |
| |
| Q_ASSERT(dstPtr); |
| Q_ASSERT(length <= sizeof(T) * 8); |
| |
| if (from >= bitLength() || !length) |
| return 0; |
| |
| T &dst = *dstPtr; |
| dst = T(); |
| length = std::min(length, bitLength() - from); |
| |
| const uchar *srcByte = first + from / 8; |
| auto bitsToRead = length + from % 8; |
| |
| while (bitsToRead > 8) { |
| dst = (dst << 8) | *srcByte; |
| bitsToRead -= 8; |
| ++srcByte; |
| } |
| |
| dst <<= bitsToRead; |
| dst |= *srcByte >> (8 - bitsToRead); |
| dst <<= sizeof(T) * 8 - length; |
| |
| return length; |
| } |
| |
| quint64 streamOffset() const |
| { |
| return offset; |
| } |
| |
| bool skipBits(quint64 nBits); |
| bool rewindOffset(quint64 nBits); |
| |
| bool read(quint32 *dstPtr); |
| bool read(QByteArray *dstPtr); |
| |
| Error error() const; |
| |
| private: |
| void setError(Error newState); |
| |
| const uchar *first; |
| const uchar *last; |
| quint64 offset; |
| Error streamError; |
| }; |
| |
| } // namespace HPack |
| |
| QT_END_NAMESPACE |
| |
| #endif |